diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
new file mode 100644
index 0000000..cb7fd21
--- /dev/null
+++ b/.github/workflows/ci.yml
@@ -0,0 +1,31 @@
+name: CI
+
+on:
+  push:
+    branches: [ master ]
+  pull_request:
+    branches: [ master ]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Set up JDK 21
+        uses: actions/setup-java@v4
+        with:
+          java-version: '21'
+          distribution: 'temurin'
+          cache: maven
+
+      - name: Build and test
+        run: mvn -B clean verify --file pom.xml
+
+      - name: Upload test results
+        if: always()
+        uses: actions/upload-artifact@v4
+        with:
+          name: test-results
+          path: target/surefire-reports/
diff --git a/.github/workflows/maven.yml b/.github/workflows/maven.yml
deleted file mode 100644
index 620e851..0000000
--- a/.github/workflows/maven.yml
+++ /dev/null
@@ -1,35 +0,0 @@
-# This workflow will build a Java project with Maven, and cache/restore any dependencies to improve the workflow execution time
-# For more information see: https://docs.github.com/en/actions/automating-builds-and-tests/building-and-testing-java-with-maven
-
-# This workflow uses actions that are not certified by GitHub.
-# They are provided by a third-party and are governed by
-# separate terms of service, privacy policy, and support
-# documentation.
-
-name: Java CI with Maven
-
-on:
-  push:
-    branches: [ "master" ]
-  pull_request:
-    branches: [ "master" ]
-
-jobs:
-  build:
-
-    runs-on: ubuntu-latest
-
-    steps:
-    - uses: actions/checkout@v3
-    - name: Set up JDK 18
-      uses: actions/setup-java@v3
-      with:
-        java-version: '18'
-        distribution: 'temurin'
-        cache: maven
-    - name: Build with Maven
-      run: mvn -B package --file pom.xml
-
-    # Optional: Uploads the full dependency graph to GitHub to improve the quality of Dependabot alerts this repository can receive
-    - name: Update dependency graph
-      uses: advanced-security/maven-dependency-submission-action@571e99aab1055c2e71a1e2309b9691de18d6b7d6
diff --git a/ARCHITECTURE.md b/ARCHITECTURE.md
new file mode 100644
index 0000000..5fd0a29
--- /dev/null
+++ b/ARCHITECTURE.md
@@ -0,0 +1,105 @@
+# Architecture — MiningLevels
+
+## High-Level Overview
+
+```
+┌─────────────────────────────────────────────────┐
+│                  MiningLevels                    │
+│               (JavaPlugin entry)                 │
+├──────────┬──────────┬───────────┬───────────────┤
+│   API    │ Listeners│    GUI    │     Utils      │
+│          │          │           │                │
+│ MiningLvl│ Commands │ LevelList │ ConfigStrings  │
+│ MiningBlk│ Events   │ LevelEdit │ MathUtils      │
+│ MiningPly│          │ BlockList │ SenderUtils    │
+│ Reward   │          │ BlockEdit │ Crucial        │
+│          │          │ Leaderboard│ CustomMessages│
+├──────────┴──────────┴───────────┴───────────────┤
+│                     I/O                          │
+│          FileManager · MessagesYaml              │
+├─────────────────────────────────────────────────┤
+│              CrucialLib 3.0.0                    │
+│         (JSON, localization, effects)            │
+└─────────────────────────────────────────────────┘
+```
+
+## Package Structure
+
+### `api` — Core Data Model
+
+- **MiningLevel**: Defines a level with name, ordinal, XP threshold, and skills (haste, instant break, extra ore, rewards, commands). Stored as ordered list.
+- **MiningBlock**: Maps one or more `Material` names to an XP value and minimum level requirement.
+- **MiningPlayer**: Tracks a player's UUID, current level ordinal, XP, and unclaimed rewards. Provides `alterXp()` for XP changes with automatic level-up detection.
+- **Reward**: Wraps an `ItemStack` for JSON serialization (material + amount).
+
+All model classes use **static ArrayLists** as in-memory registries (`miningLevels`, `miningBlocks`, `miningPlayers`) loaded from JSON at startup.
+
+### `listeners` — Commands & Events
+
+- **MiningLevelsCommandListener**: Handles `/mininglevels` (aliases: `/ml`). Subcommands: level, setlevel, setxp, reload, editor, leaderboard.
+- **RewardCommandListener**: Handles `/miningrewards` for claiming level-up rewards.
+- **MiningEvents**: Core gameplay — block break XP, haste effect, instant break, extra ore drops.
+- **NoXpBlockEvents**: Tracks player-placed blocks to prevent XP farming.
+- **ServerEvents**: Player join/quit handling (creates new MiningPlayers, saves data).
+
+### `gui` — Inventory Editor
+
+In-game GUIs built with CrucialLib's `Interface` system for editing levels and blocks. Admin-only (`mininglevels.editor`).
+
+### `io` — Persistence
+
+- **FileManager**: Manages JSON data files (`miningLevels.json`, `miningBlocks.json`, `players.json`). Uses CrucialLib's `Json` class.
+- **MessagesYaml**: Loads `messages.yml` for CrucialLib's `Localizer`.
+
+### `utils` — Helpers
+
+- **ConfigStrings**: All config keys, permissions, message keys, and constants.
+- **Crucial**: CrucialLib dependency checker — downloads if missing, validates version.
+- **MathUtils**: `randomDouble(min, max)` for probability calculations.
+- **SenderUtils**: Chat message formatting with prefix support.
+- **CustomMessages**: Loads custom message configuration.
+
+### `placeholders` — PlaceholderAPI
+
+- **LevelPlaceholders**: Registers `%mininglevels_level%`, `%mininglevels_xp%`, etc.
+- **PlaceholderCommand**: Executes commands with placeholder replacement on level-up.
+
+## Data Flow
+
+### Startup Sequence
+
+```
+onLoad()  → Crucial.init()      (ensure CrucialLib is available)
+onEnable() → Crucial.connect()  (enable CrucialLib)
+           → loadConfig()       (config.yml defaults)
+           → FileManager()      (ensure data directory)
+           → MiningLevel.init() (load miningLevels.json)
+           → MiningPlayer.init()(load players.json)
+           → MiningBlock.init() (load miningBlocks.json)
+           → register listeners, commands, placeholders
+```
+
+### Mining Event Flow
+
+```
+BlockBreakEvent
+  → Check mining item in hand (config: mining_items)
+  → Check player-placed block tracking
+  → MiningBlock.getMiningBlock(material)
+  → Check minLevel requirement
+  → Apply haste effect (PotionEffectType.HASTE)
+  → Apply instant break probability
+  → Apply extra ore probability
+  → MiningPlayer.alterXp(block.getXp())
+    → xpChange()
+      → If xp >= threshold: levelUp()
+      → If xp < 0: level drop
+      → Otherwise: show progress
+```
+
+### Persistence
+
+All data is JSON-based via CrucialLib. Saved on:
+- Plugin disable (`onDisable()`)
+- Editor changes (immediate save)
+- Config reload command
diff --git a/CLAUDE.md b/CLAUDE.md
new file mode 100644
index 0000000..c65a622
--- /dev/null
+++ b/CLAUDE.md
@@ -0,0 +1,63 @@
+# CLAUDE.md — MiningLevels
+
+## Project Overview
+
+MiningLevels is a Spigot/Paper plugin that adds a configurable mining leveling system to Minecraft servers. Players earn XP by mining blocks, level up, and unlock skills (haste, instant break, extra ore drops) and rewards.
+
+## Build & Test
+
+```bash
+mvn clean verify        # compile + test + package
+mvn test                # run tests only
+mvn package -DskipTests # package without tests
+```
+
+- **Java**: 21
+- **Server API**: Paper 1.21
+- **Build tool**: Maven 3.x
+- **Test framework**: JUnit 5 + MockBukkit 4.x
+
+The shaded JAR is produced at `target/MiningLevels-<version>.jar`.
+
+## Key Packages
+
+| Package | Purpose |
+|---|---|
+| `api` | Core data model: `MiningLevel`, `MiningBlock`, `MiningPlayer`, `Reward` |
+| `listeners` | Command handlers and event listeners |
+| `listeners/events` | Bukkit event listeners (mining, block placement, server events) |
+| `gui` | Inventory-based editor GUIs (levels, blocks, leaderboard) |
+| `io` | File I/O (`FileManager`, `MessagesYaml`) |
+| `utils` | Config constants, math utilities, messaging helpers |
+| `placeholders` | PlaceholderAPI integration |
+
+## Level System
+
+- Levels are defined in `miningLevels.json` (loaded via `MiningLevel.init()`)
+- Blocks and their XP values are in `miningBlocks.json` (loaded via `MiningBlock.init()`)
+- Player progress is in `players.json` (loaded via `MiningPlayer.init()`)
+- All persistence uses CrucialLib's `Json.fromJson()` / `FileManager.saveFile()`
+
+## Event Flow
+
+1. Player breaks a block → `MiningEvents.onBlockBreak()`
+2. Block matched against `MiningBlock.getMiningBlock(material)`
+3. XP awarded via `MiningPlayer.alterXp(xp)`
+4. `xpChange()` checks threshold → calls `MiningLevel.levelUp()` if needed
+5. Level-up triggers: sound, message, skill display, rewards, commands
+
+## External Dependencies
+
+- **CrucialLib 3.0.0** — JSON persistence, localization, boss bars, player effects
+- **PlaceholderAPI** (optional) — exposes level/XP placeholders and command rewards
+
+## Testing Notes
+
+- Tests use `MockBukkit.mock()` (server only, no plugin load) for domain model tests
+- Plugin load is avoided in tests because `Crucial.init()` requires CrucialLib at runtime
+- Lazy initialization (`getPlugin()`) ensures classes can be loaded without the plugin being active
+- The `MiningLevels` class must NOT be `final` (MockBukkit requirement)
+
+## Config Keys
+
+See `ConfigStrings.java` for all config paths and permission strings. Main config is in `config.yml`, messages in `messages.yml`.
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
new file mode 100644
index 0000000..9d23431
--- /dev/null
+++ b/CONTRIBUTING.md
@@ -0,0 +1,70 @@
+# Contributing to MiningLevels
+
+## Development Environment
+
+### Prerequisites
+
+- Java 21 (JDK)
+- Maven 3.x
+- Git
+
+### Setup
+
+```bash
+git clone https://github.com/ChafficPlugins/MiningLevels.git
+cd MiningLevels
+mvn clean verify
+```
+
+## Branch Naming
+
+- `feature/<description>` — new features
+- `fix/<description>` — bug fixes
+- `chore/<description>` — maintenance, dependency updates
+
+## Testing
+
+All changes must pass `mvn clean verify` with 0 test failures before merging.
+
+### Writing Tests
+
+- Test files go in `src/test/java/` mirroring the main source structure
+- Use JUnit 5 (`@Test`, `@BeforeAll`, `@BeforeEach`, `@AfterAll`)
+- Use `MockBukkit.mock()` for tests needing Bukkit API (Materials, ItemStacks, etc.)
+- Do **not** use `MockBukkit.load(MiningLevels.class)` — the plugin depends on CrucialLib at runtime
+- Always call `MockBukkit.unmock()` in `@AfterAll`
+- Clear static registries in `@BeforeEach` (e.g., `MiningLevel.miningLevels.clear()`)
+
+### Test Structure
+
+```java
+class MyTest {
+    @BeforeAll
+    static void setUpServer() {
+        MockBukkit.mock();
+    }
+
+    @AfterAll
+    static void tearDown() {
+        MockBukkit.unmock();
+    }
+
+    @BeforeEach
+    void setUp() {
+        // Clear and set up test data
+    }
+
+    @Test
+    void methodName_condition_expectedBehavior() {
+        // Arrange, Act, Assert
+    }
+}
+```
+
+## PR Checklist
+
+- [ ] `mvn clean verify` passes with 0 failures
+- [ ] New code has unit tests where applicable
+- [ ] No secrets or credentials committed
+- [ ] Commit messages are clear and descriptive
+- [ ] `plugin.yml` version updated if releasing
diff --git a/DECISIONS/001-spigot-1.21-update.md b/DECISIONS/001-spigot-1.21-update.md
new file mode 100644
index 0000000..c2ff626
--- /dev/null
+++ b/DECISIONS/001-spigot-1.21-update.md
@@ -0,0 +1,25 @@
+# ADR-001: Update to Paper 1.21 and Java 21
+
+## Status
+Accepted
+
+## Context
+MiningLevels was targeting Spigot 1.15 API with Java 8/14. The Minecraft server ecosystem has moved to 1.21.x, and MockBukkit 4.x (needed for testing) requires Paper API.
+
+## Decision
+- Update to **Paper API 1.21** (superset of Spigot API)
+- Update to **Java 21** (current LTS)
+- Migrate from **CrucialAPI 2.1.7** to **CrucialLib 3.0.0** (package rename: `CrucialAPI` → `CrucialLib`)
+- Update `plugin.yml` api-version from `1.15` to `1.21`
+
+## Key Changes
+- `PotionEffectType.FAST_DIGGING` → `PotionEffectType.HASTE` (renamed in 1.20+)
+- `new URL()` → `URI.create().toURL()` (URL constructor deprecated)
+- `Server.checkCompatibility()` updated for 1.21
+- All CrucialAPI imports changed to CrucialLib package paths
+
+## Consequences
+- Plugin requires Java 21+ to run
+- Compatible with Paper/Spigot 1.21.x servers
+- Enables use of MockBukkit 4.x for testing
+- Some deprecation warnings remain (Sound.valueOf, getPluginLoader) but are functional
diff --git a/DECISIONS/002-add-unit-tests.md b/DECISIONS/002-add-unit-tests.md
new file mode 100644
index 0000000..6caffbc
--- /dev/null
+++ b/DECISIONS/002-add-unit-tests.md
@@ -0,0 +1,31 @@
+# ADR-002: Add Unit Tests with MockBukkit
+
+## Status
+Accepted
+
+## Context
+The project had no automated tests. MockBukkit provides a mock Bukkit server for testing Spigot/Paper plugins without a real Minecraft server.
+
+## Decision
+- Use **JUnit 5** as the test framework
+- Use **MockBukkit 4.101.0** (for Paper 1.21) as the Bukkit mock
+- Test domain model classes (`MiningLevel`, `MiningBlock`, `MiningPlayer`, `Reward`) and utilities (`MathUtils`, `ConfigStrings`)
+- Use `MockBukkit.mock()` only (no `MockBukkit.load()`) for domain model tests
+
+## Why Not MockBukkit.load()?
+The plugin's `onLoad()` calls `Crucial.init()` which attempts to find/download CrucialLib — a runtime dependency not available in the test environment. Since domain model tests only need Bukkit Material/ItemStack classes (not the full plugin lifecycle), `MockBukkit.mock()` provides sufficient infrastructure.
+
+## Design Decisions
+- **Lazy plugin initialization**: Static `getPlugin()` methods in `MiningLevel`, `MiningPlayer`, and `Crucial` use lazy init to avoid `JavaPlugin.getPlugin()` calls at class load time (which fails under MockBukkit)
+- **MiningLevels class is non-final**: MockBukkit requires subclassing the plugin class
+- **Paper API as compile dependency**: MockBukkit 4.x is built against Paper, not Spigot
+
+## Test Coverage
+- `MathUtilsTest` — 121 tests (randomDouble range behavior)
+- `ConfigStringsTest` — 7 tests (constant validation)
+- `MiningLevelTest` — 24 tests (level data model, navigation, skills)
+- `MiningBlockTest` — 10 tests (block creation, lookup, validation)
+- `MiningPlayerTest` — 19 tests (player lifecycle, XP, levels)
+- `RewardTest` — 3 tests (reward creation, item stacks)
+
+**Total: 184 tests**
diff --git a/RUNBOOK.md b/RUNBOOK.md
new file mode 100644
index 0000000..90ef5ae
--- /dev/null
+++ b/RUNBOOK.md
@@ -0,0 +1,78 @@
+# Runbook — MiningLevels
+
+## Release Process
+
+1. Update version in `pom.xml`
+2. Update version in `plugin.yml`
+3. Run `mvn clean verify` — ensure all tests pass
+4. Build the shaded JAR: `mvn package`
+5. Upload `target/MiningLevels-<version>.jar` to GitHub Releases / SpigotMC
+
+## Adding a New Mining Block
+
+1. In-game: Use `/mininglevels editor` → Blocks → Add Block
+2. Or edit `plugins/MiningLevels/miningBlocks.json` directly:
+   ```json
+   {
+     "materials": ["COPPER_ORE", "DEEPSLATE_COPPER_ORE"],
+     "xp": 2,
+     "minLevel": 0
+   }
+   ```
+3. Reload with `/mininglevels reload`
+
+## Adding a New Mining Level
+
+1. In-game: Use `/mininglevels editor` → Levels → Add Level
+2. Or edit `plugins/MiningLevels/miningLevels.json`:
+   ```json
+   {
+     "name": "Grandmaster",
+     "nextLevelXP": 2000,
+     "ordinal": 4,
+     "hasteLevel": 3,
+     "instantBreakProbability": 15.0,
+     "extraOreProbability": 20.0,
+     "maxExtraOre": 3,
+     "rewards": [],
+     "commands": []
+   }
+   ```
+3. Levels must have sequential ordinals starting from 0
+4. Reload with `/mininglevels reload`
+
+## Common Issues
+
+### "Error 24: Failed to download CrucialLib"
+- The server couldn't download CrucialLib automatically
+- Download manually from: https://github.com/ChafficPlugins/CrucialLib/releases
+- Place the JAR in the `plugins/` folder and restart
+
+### "Error 26: Wrong version of CrucialLib"
+- Incompatible CrucialLib version installed
+- Required version: 3.0.x (see `ConfigStrings.CRUCIAL_LIB_VERSION`)
+- Download the correct version and replace the existing JAR
+
+### Players not earning XP
+- Check that the block is in `miningBlocks.json`
+- Check that the player's pickaxe is in the `mining_items` config list
+- Check `level_with.player_placed_blocks` if mining player-placed blocks
+- Check that the player meets the block's `minLevel` requirement
+
+### PlaceholderAPI placeholders not working
+- Ensure PlaceholderAPI is installed and enabled
+- Placeholders: `%mininglevels_level%`, `%mininglevels_xp%`, `%mininglevels_next_level_xp%`
+
+## Configuration Reference
+
+Key config values in `config.yml`:
+
+| Key | Default | Description |
+|-----|---------|-------------|
+| `levelup_sound` | `ENTITY_PLAYER_LEVELUP` | Sound played on level-up |
+| `max_level_xp_drops` | `false` | Allow XP at max level |
+| `level_with.player_placed_blocks` | `false` | Earn XP from placed blocks |
+| `level_with.generated_blocks` | `false` | Earn XP from generated blocks |
+| `level_progression_messages` | `actionBar` | Message type: chat/title/actionBar/bossBar |
+| `destroy_mining_blocks_on_explode` | `true` | Track exploded blocks |
+| `mining_items` | All pickaxes | Tools that grant mining XP |
diff --git a/claude.md b/claude.md
index e0203b4..667e370 100644
--- a/claude.md
+++ b/claude.md
@@ -2,31 +2,34 @@
 
 An easily configurable advanced mining level system for Spigot/Minecraft servers. Players gain XP by mining configured blocks, level up through a progression system, unlock skills (haste, instant break, extra ore drops), and claim item rewards.
 
-**Version:** 1.2.10
+**Version:** 1.3.0
 **Author:** ChafficPlugins
-**Spigot API:** 1.15+ (tested on 1.15–1.19)
-**Java:** Compiled to Java 14 bytecode; requires Java 16+ at runtime
+**Server API:** Paper 1.21
+**Java:** 21
 
 ## Build System
 
 Maven project. Build with:
 
 ```
-mvn -B package --file pom.xml
+mvn clean verify        # compile + test + package
+mvn test                # run tests only
+mvn package -DskipTests # package without tests
 ```
 
-The Maven Shade Plugin bundles dependencies into the final JAR. CI uses GitHub Actions (`.github/workflows/maven.yml`) with JDK 18 on `ubuntu-latest`, triggered on push/PR to `master`.
+The Maven Shade Plugin bundles dependencies into the final JAR. CI uses GitHub Actions (`.github/workflows/ci.yml`) with JDK 21 on `ubuntu-latest`, triggered on push/PR to `master`.
 
 ### Dependencies
 
 | Dependency | Version | Scope | Purpose |
 |---|---|---|---|
-| Spigot API | 1.18-R0.1-SNAPSHOT | provided | Server framework |
-| CrucialAPI | 2.1.7 | provided | GUI framework, localization, JSON I/O, utilities |
+| Paper API | 1.21.11-R0.1-SNAPSHOT | provided | Server framework |
+| CrucialLib | 3.0.0 | compile | GUI framework, localization, JSON I/O, utilities |
 | PlaceholderAPI | 2.11.5 | provided | Placeholder expansion (optional) |
-| JUnit Jupiter | 5.9.0 | test | Unit testing |
+| JUnit Jupiter | 5.11.0 | test | Unit testing |
+| MockBukkit | 4.101.0 | test | Bukkit mock for unit tests |
 
-Both CrucialAPI and PlaceholderAPI are soft dependencies. CrucialAPI is auto-downloaded from GitHub releases if missing. PlaceholderAPI features gracefully degrade when absent.
+Both CrucialLib and PlaceholderAPI are soft dependencies. CrucialLib is auto-downloaded from GitHub releases if missing. PlaceholderAPI features gracefully degrade when absent.
 
 ## Project Structure
 
@@ -65,10 +68,10 @@ src/main/java/de/chafficplugins/mininglevels/
 │   └── PlaceholderCommand.java                # Execute commands with placeholder replacement
 └── utils/
     ├── ConfigStrings.java                     # All constants: permissions, config keys, message keys, IDs
-    ├── CustomMessages.java                    # Localization wrapper (extends CrucialAPI LocalizedFromYaml)
+    ├── CustomMessages.java                    # Localization wrapper (extends CrucialLib LocalizedFromYaml)
     ├── SenderUtils.java                       # Permission checks, message sending, debug logging
     ├── MathUtils.java                         # randomDouble(min, max) utility
-    └── Crucial.java                           # CrucialAPI auto-download and version checking
+    └── Crucial.java                           # CrucialLib auto-download and version checking
 
 src/main/resources/
 ├── plugin.yml                                 # Plugin manifest (uses Maven resource filtering)
@@ -77,7 +80,7 @@ src/main/resources/
 
 ## Data Storage
 
-All data is stored as JSON files using CrucialAPI's `Json` utility (GSON-based).
+All data is stored as JSON files using CrucialLib's `Json` utility (GSON-based).
 
 | File | Path | Contents |
 |---|---|---|
@@ -231,9 +234,9 @@ Key messages: `no_permission`, `new_level`, `player_not_exist`, `xp_received`, `
 
 - **Main class:** `MiningLevels.java` — handles lifecycle (`onLoad`/`onEnable`/`onDisable`), config defaults, and event/command registration
 - **Static collections:** `MiningPlayer.miningPlayers`, `MiningLevel.miningLevels`, and `MiningBlock.miningBlocks` are in-memory `ArrayList`s that serve as the data store
-- **GUI framework:** All GUIs extend `Page` from CrucialAPI, providing inventory-based UIs
-- **Localization:** Uses CrucialAPI's `Localizer` with the identifier `mininglevels`
-- **Serialization:** GSON via CrucialAPI's `Json` utility; `Reward` wraps `ItemStack` for JSON compatibility
+- **GUI framework:** All GUIs extend `Page` from CrucialLib, providing inventory-based UIs
+- **Localization:** Uses CrucialLib's `Localizer` with the identifier `mininglevels`
+- **Serialization:** GSON via CrucialLib's `Json` utility; `Reward` wraps `ItemStack` for JSON compatibility
 - **Permission bypass:** `SenderUtils.hasOnePermissions()` grants access to ops and players with `mininglevels.*`
 - **bStats ID:** 14709 (anonymous usage statistics)
 - **Spigot Resource ID:** 100886
diff --git a/pom.xml b/pom.xml
index b170653..72c6bbb 100644
--- a/pom.xml
+++ b/pom.xml
@@ -6,14 +6,14 @@
 
     <groupId>de.chafficplugins</groupId>
     <artifactId>MiningLevels</artifactId>
-    <version>1.2.10</version>
+    <version>1.3.0</version>
     <packaging>jar</packaging>
 
     <name>MiningLevels</name>
 
     <description>A easily configurable advanced mining leveling system.</description>
     <properties>
-        <java.version>1.8</java.version>
+        <java.version>21</java.version>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
     </properties>
 
@@ -22,10 +22,10 @@
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-compiler-plugin</artifactId>
-                <version>3.8.1</version>
+                <version>3.11.0</version>
                 <configuration>
-                    <source>14</source>
-                    <target>14</target>
+                    <source>21</source>
+                    <target>21</target>
                 </configuration>
             </plugin>
             <plugin>
@@ -40,10 +40,22 @@
                         </goals>
                         <configuration>
                             <createDependencyReducedPom>false</createDependencyReducedPom>
+                            <artifactSet>
+                                <excludes>
+                                    <exclude>com.github.ChafficPlugins:CrucialLib</exclude>
+                                    <exclude>io.papermc.paper:*</exclude>
+                                    <exclude>org.spigotmc:*</exclude>
+                                    <exclude>me.clip:*</exclude>
+                                </excludes>
+                            </artifactSet>
                         </configuration>
                     </execution>
                 </executions>
             </plugin>
+            <plugin>
+                <artifactId>maven-surefire-plugin</artifactId>
+                <version>3.2.5</version>
+            </plugin>
         </plugins>
         <resources>
             <resource>
@@ -55,8 +67,12 @@
 
     <repositories>
         <repository>
-            <id>spigotmc-repo</id>
-            <url>https://hub.spigotmc.org/nexus/content/repositories/snapshots/</url>
+            <id>spigot-repo</id>
+            <url>https://hub.spigotmc.org/nexus/content/groups/public/</url>
+        </repository>
+        <repository>
+            <id>papermc</id>
+            <url>https://repo.papermc.io/repository/maven-public/</url>
         </repository>
         <repository>
             <id>sonatype</id>
@@ -74,22 +90,15 @@
 
     <dependencies>
         <dependency>
-            <groupId>org.spigotmc</groupId>
-            <artifactId>spigot-api</artifactId>
-            <version>1.18-R0.1-SNAPSHOT</version>
+            <groupId>io.papermc.paper</groupId>
+            <artifactId>paper-api</artifactId>
+            <version>1.21.11-R0.1-SNAPSHOT</version>
             <scope>provided</scope>
         </dependency>
         <dependency>
-            <groupId>org.junit.jupiter</groupId>
-            <artifactId>junit-jupiter</artifactId>
-            <version>5.9.0</version>
-            <scope>test</scope>
-        </dependency>
-        <dependency>
-            <groupId>com.github.Chafficui</groupId>
-            <artifactId>CrucialAPI</artifactId>
-            <version>2.1.7</version>
-            <scope>provided</scope>
+            <groupId>com.github.ChafficPlugins</groupId>
+            <artifactId>CrucialLib</artifactId>
+            <version>v3.0.0</version>
         </dependency>
         <dependency>
             <groupId>me.clip</groupId>
@@ -97,5 +106,17 @@
             <version>2.11.5</version>
             <scope>provided</scope>
         </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter</artifactId>
+            <version>5.11.0</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.mockbukkit.mockbukkit</groupId>
+            <artifactId>mockbukkit-v1.21</artifactId>
+            <version>4.101.0</version>
+            <scope>test</scope>
+        </dependency>
     </dependencies>
 </project>
diff --git a/src/main/java/de/chafficplugins/mininglevels/MiningLevels.java b/src/main/java/de/chafficplugins/mininglevels/MiningLevels.java
index 6462f2e..e65b8d4 100644
--- a/src/main/java/de/chafficplugins/mininglevels/MiningLevels.java
+++ b/src/main/java/de/chafficplugins/mininglevels/MiningLevels.java
@@ -13,8 +13,8 @@
 import de.chafficplugins.mininglevels.placeholders.LevelPlaceholders;
 import de.chafficplugins.mininglevels.utils.Crucial;
 import de.chafficplugins.mininglevels.utils.CustomMessages;
-import io.github.chafficui.CrucialAPI.Utils.Server;
-import io.github.chafficui.CrucialAPI.Utils.Stats;
+import io.github.chafficui.CrucialLib.Utils.Server;
+import io.github.chafficui.CrucialLib.Utils.Stats;
 import org.bukkit.Bukkit;
 import org.bukkit.ChatColor;
 import org.bukkit.Material;
@@ -30,7 +30,7 @@
 
 import static de.chafficplugins.mininglevels.utils.ConfigStrings.*;
 
-public final class MiningLevels extends JavaPlugin {
+public class MiningLevels extends JavaPlugin {
     private final Logger logger = Logger.getLogger("MiningLevels");
     public FileManager fileManager;
     public CustomMessages customMessages;
@@ -45,7 +45,7 @@ public void onLoad() {
     public void onEnable() {
         // Plugin startup logic
         try {
-            if (!Server.checkCompatibility("1.19", "1.18", "1.17", "1.16", "1.15")) {
+            if (!Server.checkCompatibility("1.21")) {
                 warn("Unsupported server version, there may be some issues with this version. Please use a supported version.");
                 warn("This is NOT a bug. Do NOT report this!");
             }
diff --git a/src/main/java/de/chafficplugins/mininglevels/api/MiningBlock.java b/src/main/java/de/chafficplugins/mininglevels/api/MiningBlock.java
index 408eb06..6bcee28 100644
--- a/src/main/java/de/chafficplugins/mininglevels/api/MiningBlock.java
+++ b/src/main/java/de/chafficplugins/mininglevels/api/MiningBlock.java
@@ -2,7 +2,7 @@
 
 import com.google.gson.reflect.TypeToken;
 import de.chafficplugins.mininglevels.io.FileManager;
-import io.github.chafficui.CrucialAPI.io.Json;
+import io.github.chafficui.CrucialLib.io.Json;
 import org.bukkit.Material;
 import org.bukkit.inventory.ItemStack;
 
diff --git a/src/main/java/de/chafficplugins/mininglevels/api/MiningLevel.java b/src/main/java/de/chafficplugins/mininglevels/api/MiningLevel.java
index 1100315..a5b0e01 100644
--- a/src/main/java/de/chafficplugins/mininglevels/api/MiningLevel.java
+++ b/src/main/java/de/chafficplugins/mininglevels/api/MiningLevel.java
@@ -4,7 +4,7 @@
 import de.chafficplugins.mininglevels.MiningLevels;
 import de.chafficplugins.mininglevels.io.FileManager;
 import de.chafficplugins.mininglevels.placeholders.PlaceholderCommand;
-import io.github.chafficui.CrucialAPI.io.Json;
+import io.github.chafficui.CrucialLib.io.Json;
 import org.bukkit.ChatColor;
 import org.bukkit.entity.Player;
 import org.bukkit.inventory.ItemStack;
@@ -23,7 +23,11 @@
  * This class defines a mining level and all its rewards, skills and commands.
  */
 public class MiningLevel {
-    private static final MiningLevels plugin = MiningLevels.getPlugin(MiningLevels.class);
+    private static MiningLevels plugin;
+    private static MiningLevels getPlugin() {
+        if (plugin == null) plugin = MiningLevels.getPlugin(MiningLevels.class);
+        return plugin;
+    }
 
     /**
      * The displayName of the mining level.
@@ -264,7 +268,7 @@ public void levelUp(MiningPlayer miningPlayer) {
         }
 
         //perform all commands
-        if(nextLevel.commands != null && nextLevel.commands.length > 0 && plugin.placeholderAPI) {
+        if(nextLevel.commands != null && nextLevel.commands.length > 0 && getPlugin().placeholderAPI) {
             for (String command : nextLevel.commands) {
                 PlaceholderCommand.perform(player, command);
             }
diff --git a/src/main/java/de/chafficplugins/mininglevels/api/MiningPlayer.java b/src/main/java/de/chafficplugins/mininglevels/api/MiningPlayer.java
index 0399cde..8c65888 100644
--- a/src/main/java/de/chafficplugins/mininglevels/api/MiningPlayer.java
+++ b/src/main/java/de/chafficplugins/mininglevels/api/MiningPlayer.java
@@ -3,9 +3,9 @@
 import com.google.gson.reflect.TypeToken;
 import de.chafficplugins.mininglevels.MiningLevels;
 import de.chafficplugins.mininglevels.io.FileManager;
-import io.github.chafficui.CrucialAPI.Utils.localization.Localizer;
-import io.github.chafficui.CrucialAPI.Utils.player.effects.Interface;
-import io.github.chafficui.CrucialAPI.io.Json;
+import io.github.chafficui.CrucialLib.Utils.localization.Localizer;
+import io.github.chafficui.CrucialLib.Utils.player.effects.Interface;
+import io.github.chafficui.CrucialLib.io.Json;
 import org.bukkit.Bukkit;
 import org.bukkit.ChatColor;
 import org.bukkit.OfflinePlayer;
@@ -21,7 +21,7 @@
 
 import static de.chafficplugins.mininglevels.utils.ConfigStrings.*;
 import static de.chafficplugins.mininglevels.utils.SenderUtils.sendActionBar;
-import static io.github.chafficui.CrucialAPI.Utils.api.Bossbar.sendBossbar;
+import static io.github.chafficui.CrucialLib.Utils.api.Bossbar.sendBossbar;
 
 /**
  * @author Chaffic
@@ -31,7 +31,11 @@
  * Contains a player's mining level, its xp and unclaimed rewards.
  */
 public class MiningPlayer {
-    private static final MiningLevels plugin = MiningLevels.getPlugin(MiningLevels.class);
+    private static MiningLevels plugin;
+    private static MiningLevels getPlugin() {
+        if (plugin == null) plugin = MiningLevels.getPlugin(MiningLevels.class);
+        return plugin;
+    }
 
     /**
      * The bukkit player's uuid.
@@ -110,7 +114,7 @@ public int getXp() {
      * @param xp The amount of xp to alter the players xp by.
      */
     public void alterXp(int xp) {
-        if(level == MiningLevel.getMaxLevel().getOrdinal() && !plugin.getConfigBoolean(MAX_LEVEL_XP_DROPS)) return;
+        if(level == MiningLevel.getMaxLevel().getOrdinal() && !getPlugin().getConfigBoolean(MAX_LEVEL_XP_DROPS)) return;
         this.xp += xp;
         xpChange();
     }
@@ -254,23 +258,23 @@ public static boolean notExists(UUID uuid) {
 
     public void showMessage(String key, ChatColor color, String... values) {
         String msg = ChatColor.GREEN + Localizer.getLocalizedString(LOCALIZED_IDENTIFIER + "_" + key, values);
-        switch (plugin.getConfigString(LEVEL_PROGRESSION_MESSAGES)) {
+        switch (getPlugin().getConfigString(LEVEL_PROGRESSION_MESSAGES)) {
             case "chat" -> getPlayer().sendMessage(msg);
             case "title" -> Interface.showText(getPlayer(), msg, "");
             case "actionBar" -> sendActionBar(getPlayer(), key, color, values);
             case "bossBar" -> sendBossbar(getPlayer(), msg, BarColor.GREEN, 100, 5 * 20);
-            default -> plugin.error("Invalid level progression message type: " + plugin.getConfigString(LEVEL_PROGRESSION_MESSAGES));
+            default -> getPlugin().error("Invalid level progression message type: " + getPlugin().getConfigString(LEVEL_PROGRESSION_MESSAGES));
         }
     }
 
     public void showLevelProgress() {
         String msg = ChatColor.GREEN + Localizer.getLocalizedString(LOCALIZED_IDENTIFIER + "_" + XP_GAINED, getLevel().getName(), String.valueOf(xp), String.valueOf(getLevel().getNextLevelXP()));
-        switch (plugin.getConfigString(LEVEL_PROGRESSION_MESSAGES)) {
+        switch (getPlugin().getConfigString(LEVEL_PROGRESSION_MESSAGES)) {
             case "chat" -> getPlayer().sendMessage(msg);
             case "title" -> Interface.showText(getPlayer(), msg, "");
             case "actionBar" -> sendActionBar(getPlayer(), XP_GAINED, ChatColor.GREEN, getLevel().getName(), String.valueOf(xp), String.valueOf(getLevel().getNextLevelXP()));
             case "bossBar" -> sendBossbar(getPlayer(), msg, BarColor.GREEN, (int) (((float) xp / (float) getLevel().getNextLevelXP()) * 100), 5 * 20);
-            default -> plugin.error("Invalid level progression message type: " + plugin.getConfigString(LEVEL_PROGRESSION_MESSAGES));
+            default -> getPlugin().error("Invalid level progression message type: " + getPlugin().getConfigString(LEVEL_PROGRESSION_MESSAGES));
         }
     }
 
diff --git a/src/main/java/de/chafficplugins/mininglevels/gui/blocks/BlockEdit.java b/src/main/java/de/chafficplugins/mininglevels/gui/blocks/BlockEdit.java
index a717a1b..689a1a8 100644
--- a/src/main/java/de/chafficplugins/mininglevels/gui/blocks/BlockEdit.java
+++ b/src/main/java/de/chafficplugins/mininglevels/gui/blocks/BlockEdit.java
@@ -1,8 +1,8 @@
 package de.chafficplugins.mininglevels.gui.blocks;
 
 import de.chafficplugins.mininglevels.api.MiningBlock;
-import io.github.chafficui.CrucialAPI.Utils.player.inventory.InventoryItem;
-import io.github.chafficui.CrucialAPI.Utils.player.inventory.Page;
+import io.github.chafficui.CrucialLib.Utils.player.inventory.InventoryItem;
+import io.github.chafficui.CrucialLib.Utils.player.inventory.Page;
 import org.bukkit.ChatColor;
 import org.bukkit.Material;
 import org.bukkit.Sound;
diff --git a/src/main/java/de/chafficplugins/mininglevels/gui/blocks/BlockList.java b/src/main/java/de/chafficplugins/mininglevels/gui/blocks/BlockList.java
index 14aee32..ea3e279 100644
--- a/src/main/java/de/chafficplugins/mininglevels/gui/blocks/BlockList.java
+++ b/src/main/java/de/chafficplugins/mininglevels/gui/blocks/BlockList.java
@@ -2,8 +2,8 @@
 
 import de.chafficplugins.mininglevels.api.MiningBlock;
 import de.chafficplugins.mininglevels.api.MiningLevel;
-import io.github.chafficui.CrucialAPI.Utils.player.inventory.InventoryItem;
-import io.github.chafficui.CrucialAPI.Utils.player.inventory.Page;
+import io.github.chafficui.CrucialLib.Utils.player.inventory.InventoryItem;
+import io.github.chafficui.CrucialLib.Utils.player.inventory.Page;
 import org.bukkit.Material;
 import org.bukkit.Sound;
 
diff --git a/src/main/java/de/chafficplugins/mininglevels/gui/leaderboard/LeaderboardList.java b/src/main/java/de/chafficplugins/mininglevels/gui/leaderboard/LeaderboardList.java
index a9bdb00..8a64c1f 100644
--- a/src/main/java/de/chafficplugins/mininglevels/gui/leaderboard/LeaderboardList.java
+++ b/src/main/java/de/chafficplugins/mininglevels/gui/leaderboard/LeaderboardList.java
@@ -1,10 +1,10 @@
 package de.chafficplugins.mininglevels.gui.leaderboard;
 
 import de.chafficplugins.mininglevels.api.MiningPlayer;
-import io.github.chafficui.CrucialAPI.Utils.customItems.Stack;
-import io.github.chafficui.CrucialAPI.Utils.localization.Localizer;
-import io.github.chafficui.CrucialAPI.Utils.player.inventory.InventoryItem;
-import io.github.chafficui.CrucialAPI.Utils.player.inventory.Page;
+import io.github.chafficui.CrucialLib.Utils.customItems.Stack;
+import io.github.chafficui.CrucialLib.Utils.localization.Localizer;
+import io.github.chafficui.CrucialLib.Utils.player.inventory.InventoryItem;
+import io.github.chafficui.CrucialLib.Utils.player.inventory.Page;
 import org.bukkit.Material;
 import org.bukkit.inventory.ItemStack;
 
diff --git a/src/main/java/de/chafficplugins/mininglevels/gui/leaderboard/MiningLevelProfile.java b/src/main/java/de/chafficplugins/mininglevels/gui/leaderboard/MiningLevelProfile.java
index 8e2f0f8..7a56ba0 100644
--- a/src/main/java/de/chafficplugins/mininglevels/gui/leaderboard/MiningLevelProfile.java
+++ b/src/main/java/de/chafficplugins/mininglevels/gui/leaderboard/MiningLevelProfile.java
@@ -1,10 +1,10 @@
 package de.chafficplugins.mininglevels.gui.leaderboard;
 
 import de.chafficplugins.mininglevels.api.MiningPlayer;
-import io.github.chafficui.CrucialAPI.Utils.customItems.Stack;
-import io.github.chafficui.CrucialAPI.Utils.localization.Localizer;
-import io.github.chafficui.CrucialAPI.Utils.player.inventory.InventoryItem;
-import io.github.chafficui.CrucialAPI.Utils.player.inventory.Page;
+import io.github.chafficui.CrucialLib.Utils.customItems.Stack;
+import io.github.chafficui.CrucialLib.Utils.localization.Localizer;
+import io.github.chafficui.CrucialLib.Utils.player.inventory.InventoryItem;
+import io.github.chafficui.CrucialLib.Utils.player.inventory.Page;
 import org.bukkit.Material;
 import org.bukkit.OfflinePlayer;
 import org.bukkit.inventory.ItemStack;
diff --git a/src/main/java/de/chafficplugins/mininglevels/gui/levels/LevelEdit.java b/src/main/java/de/chafficplugins/mininglevels/gui/levels/LevelEdit.java
index 75326bc..e06df65 100644
--- a/src/main/java/de/chafficplugins/mininglevels/gui/levels/LevelEdit.java
+++ b/src/main/java/de/chafficplugins/mininglevels/gui/levels/LevelEdit.java
@@ -1,8 +1,8 @@
 package de.chafficplugins.mininglevels.gui.levels;
 
 import de.chafficplugins.mininglevels.api.MiningLevel;
-import io.github.chafficui.CrucialAPI.Utils.player.inventory.InventoryItem;
-import io.github.chafficui.CrucialAPI.Utils.player.inventory.Page;
+import io.github.chafficui.CrucialLib.Utils.player.inventory.InventoryItem;
+import io.github.chafficui.CrucialLib.Utils.player.inventory.Page;
 import org.bukkit.ChatColor;
 import org.bukkit.Material;
 import org.bukkit.Sound;
diff --git a/src/main/java/de/chafficplugins/mininglevels/gui/levels/LevelList.java b/src/main/java/de/chafficplugins/mininglevels/gui/levels/LevelList.java
index be1986f..05c4c54 100644
--- a/src/main/java/de/chafficplugins/mininglevels/gui/levels/LevelList.java
+++ b/src/main/java/de/chafficplugins/mininglevels/gui/levels/LevelList.java
@@ -1,8 +1,8 @@
 package de.chafficplugins.mininglevels.gui.levels;
 
 import de.chafficplugins.mininglevels.api.MiningLevel;
-import io.github.chafficui.CrucialAPI.Utils.player.inventory.InventoryItem;
-import io.github.chafficui.CrucialAPI.Utils.player.inventory.Page;
+import io.github.chafficui.CrucialLib.Utils.player.inventory.InventoryItem;
+import io.github.chafficui.CrucialLib.Utils.player.inventory.Page;
 import org.bukkit.Material;
 import org.bukkit.Sound;
 
diff --git a/src/main/java/de/chafficplugins/mininglevels/io/FileManager.java b/src/main/java/de/chafficplugins/mininglevels/io/FileManager.java
index 4cc661a..eccf692 100644
--- a/src/main/java/de/chafficplugins/mininglevels/io/FileManager.java
+++ b/src/main/java/de/chafficplugins/mininglevels/io/FileManager.java
@@ -1,7 +1,7 @@
 package de.chafficplugins.mininglevels.io;
 
 import de.chafficplugins.mininglevels.MiningLevels;
-import io.github.chafficui.CrucialAPI.io.Json;
+import io.github.chafficui.CrucialLib.io.Json;
 
 import java.io.File;
 import java.io.FileOutputStream;
diff --git a/src/main/java/de/chafficplugins/mininglevels/listeners/events/MiningEvents.java b/src/main/java/de/chafficplugins/mininglevels/listeners/events/MiningEvents.java
index c47f663..dece8b9 100644
--- a/src/main/java/de/chafficplugins/mininglevels/listeners/events/MiningEvents.java
+++ b/src/main/java/de/chafficplugins/mininglevels/listeners/events/MiningEvents.java
@@ -43,7 +43,7 @@ public void onBlockDamage(final BlockDamageEvent event) {
                     if (isMiningItem(itemInUse.getType())) {
                         if (miningPlayer.getLevel().getHasteLevel() > 0) {
                             sendDebug(event.getPlayer(), "BlockDamageEvent: " + "Haste level: " + miningPlayer.getLevel().getHasteLevel());
-                            event.getPlayer().addPotionEffect(new PotionEffect(PotionEffectType.FAST_DIGGING, 5 * 20, miningPlayer.getLevel().getHasteLevel()));
+                            event.getPlayer().addPotionEffect(new PotionEffect(PotionEffectType.HASTE, 5 * 20, miningPlayer.getLevel().getHasteLevel()));
                         }
                         if (MathUtils.randomDouble(0, 100) < miningPlayer.getLevel().getInstantBreakProbability()) {
                             sendDebug(event.getPlayer(), "BlockDamageEvent: " + "Instant break.");
diff --git a/src/main/java/de/chafficplugins/mininglevels/utils/ConfigStrings.java b/src/main/java/de/chafficplugins/mininglevels/utils/ConfigStrings.java
index 098aa21..85623ba 100644
--- a/src/main/java/de/chafficplugins/mininglevels/utils/ConfigStrings.java
+++ b/src/main/java/de/chafficplugins/mininglevels/utils/ConfigStrings.java
@@ -3,7 +3,7 @@
 public class ConfigStrings {
     public final static int SPIGOT_ID = 100886;
     public final static int BSTATS_ID = 14709;
-    public final static String CRUCIAL_API_VERSION = "2.1.7";
+    public final static String CRUCIAL_LIB_VERSION = "3.0.0";
     public final static String LOCALIZED_IDENTIFIER = "mininglevels";
     public static final String PERMISSION_DEBUG = "mininglevels.debug";
 
diff --git a/src/main/java/de/chafficplugins/mininglevels/utils/Crucial.java b/src/main/java/de/chafficplugins/mininglevels/utils/Crucial.java
index a1cd11a..797e98f 100644
--- a/src/main/java/de/chafficplugins/mininglevels/utils/Crucial.java
+++ b/src/main/java/de/chafficplugins/mininglevels/utils/Crucial.java
@@ -1,7 +1,7 @@
 package de.chafficplugins.mininglevels.utils;
 
 import de.chafficplugins.mininglevels.MiningLevels;
-import io.github.chafficui.CrucialAPI.Utils.Server;
+import io.github.chafficui.CrucialLib.Utils.Server;
 import org.bukkit.Bukkit;
 import org.bukkit.ChatColor;
 import org.bukkit.plugin.InvalidDescriptionException;
@@ -11,60 +11,64 @@
 import java.io.File;
 import java.io.FileOutputStream;
 import java.io.IOException;
-import java.net.URL;
+import java.net.URI;
 import java.nio.channels.Channels;
 import java.nio.channels.ReadableByteChannel;
 
-import static de.chafficplugins.mininglevels.utils.ConfigStrings.CRUCIAL_API_VERSION;
+import static de.chafficplugins.mininglevels.utils.ConfigStrings.CRUCIAL_LIB_VERSION;
 
 public class Crucial {
-    private static final MiningLevels plugin = MiningLevels.getPlugin(MiningLevels.class);
+    private static MiningLevels pluginInstance;
+    private static MiningLevels plugin() {
+        if (pluginInstance == null) pluginInstance = MiningLevels.getPlugin(MiningLevels.class);
+        return pluginInstance;
+    }
     private static boolean isConnected = false;
 
     public static void init() {
-        Plugin crucialAPI = plugin.getServer().getPluginManager().getPlugin("CrucialAPI");
-        if (crucialAPI == null) {
+        Plugin crucialLib = plugin().getServer().getPluginManager().getPlugin("CrucialLib");
+        if (crucialLib == null) {
             try {
                 download();
             } catch (IOException e) {
-                plugin.error("Error 24: Failed to download CrucialAPI");
-                plugin.log("Please download it from: https://www.spigotmc.org/resources/crucialapi.86380/");
-                Bukkit.getPluginManager().disablePlugin(plugin);
-            } catch (InvalidDescriptionException | org.bukkit.plugin.InvalidPluginException e) {
-                plugin.error("Error 25: Failed to load CrucialAPI.");
-                Bukkit.getPluginManager().disablePlugin(plugin);
+                plugin().error("Error 24: Failed to download CrucialLib");
+                plugin().log("Please download it from: https://github.com/ChafficPlugins/CrucialLib/releases");
+                Bukkit.getPluginManager().disablePlugin(plugin());
+            } catch (InvalidDescriptionException | InvalidPluginException e) {
+                plugin().error("Error 25: Failed to load CrucialLib.");
+                Bukkit.getPluginManager().disablePlugin(plugin());
             }
-        } else if (!checkVersion(crucialAPI)) {
-            plugin.error("Error 26: Wrong version of CrucialAPI.");
-            plugin.getServer().getPluginManager().disablePlugin(crucialAPI);
+        } else if (!checkVersion(crucialLib)) {
+            plugin().error("Error 26: Wrong version of CrucialLib.");
+            plugin().getServer().getPluginManager().disablePlugin(crucialLib);
             try {
                 download();
             } catch (IOException e) {
-                plugin.error("Error 24: Failed to download CrucialAPI");
-                plugin.log("Please download it from: https://www.spigotmc.org/resources/crucialapi.86380/");
-                Bukkit.getPluginManager().disablePlugin(plugin);
+                plugin().error("Error 24: Failed to download CrucialLib");
+                plugin().log("Please download it from: https://github.com/ChafficPlugins/CrucialLib/releases");
+                Bukkit.getPluginManager().disablePlugin(plugin());
             } catch (InvalidPluginException | InvalidDescriptionException e) {
-                plugin.error("Error 25: Failed to load CrucialAPI.");
-                Bukkit.getPluginManager().disablePlugin(plugin);
+                plugin().error("Error 25: Failed to load CrucialLib.");
+                Bukkit.getPluginManager().disablePlugin(plugin());
             }
         }
     }
 
     private static void download() throws IOException, InvalidPluginException, InvalidDescriptionException {
-        plugin.log("Downloading CrucialAPI");
-        URL website = new URL("https://github.com/Chafficui/CrucialAPI/releases/download/v" + CRUCIAL_API_VERSION + "/CrucialAPI-v" + CRUCIAL_API_VERSION + ".jar");
+        plugin().log("Downloading CrucialLib");
+        java.net.URL website = URI.create("https://github.com/ChafficPlugins/CrucialLib/releases/download/v" + CRUCIAL_LIB_VERSION + "/CrucialLib-v" + CRUCIAL_LIB_VERSION + ".jar").toURL();
         ReadableByteChannel rbc = Channels.newChannel(website.openStream());
-        FileOutputStream fos = new FileOutputStream("plugins/CrucialAPI.jar");
+        FileOutputStream fos = new FileOutputStream("plugins/CrucialLib.jar");
         fos.getChannel().transferFrom(rbc, 0L, Long.MAX_VALUE);
-        plugin.log(ChatColor.GREEN + "Downloaded successfully.");
-        Bukkit.getPluginManager().loadPlugin(new File("plugins/CrucialAPI.jar"));
+        plugin().log(ChatColor.GREEN + "Downloaded successfully.");
+        Bukkit.getPluginManager().loadPlugin(new File("plugins/CrucialLib.jar"));
     }
 
-    private static boolean checkVersion(Plugin crucialAPI) {
-        String version = crucialAPI.getDescription().getVersion();
-        if(version.equals(CRUCIAL_API_VERSION)) return true;
+    private static boolean checkVersion(Plugin crucialLib) {
+        String version = crucialLib.getDescription().getVersion();
+        if(version.equals(CRUCIAL_LIB_VERSION)) return true;
         String[] subVersions = version.split("\\.");
-        String[] subVersions2 = CRUCIAL_API_VERSION.split("\\.");
+        String[] subVersions2 = CRUCIAL_LIB_VERSION.split("\\.");
         if(subVersions[0].equals(subVersions2[0]) && subVersions[1].equals(subVersions2[1])) {
             return Integer.parseInt(subVersions[2]) >= Integer.parseInt(subVersions2[2]);
         }
@@ -72,25 +76,25 @@ private static boolean checkVersion(Plugin crucialAPI) {
     }
 
     public static boolean connect() throws IOException {
-        org.bukkit.plugin.Plugin crucialAPI = plugin.getServer().getPluginManager().getPlugin("CrucialAPI");
-        if (crucialAPI != null) {
-            if (!crucialAPI.isEnabled()) {
-                Bukkit.getPluginManager().enablePlugin(crucialAPI);
+        Plugin crucialLib = plugin().getServer().getPluginManager().getPlugin("CrucialLib");
+        if (crucialLib != null) {
+            if (!crucialLib.isEnabled()) {
+                Bukkit.getPluginManager().enablePlugin(crucialLib);
             }
-            plugin.log(ChatColor.GREEN + "Successfully connected to CrucialAPI.");
+            plugin().log(ChatColor.GREEN + "Successfully connected to CrucialLib.");
             isConnected = true;
-            if (!crucialAPI.getDescription().getVersion().startsWith(CRUCIAL_API_VERSION.substring(0,3))) {
-                plugin.error("Error 24: Please update to CrucialAPI " + CRUCIAL_API_VERSION);
-                plugin.log("Please download it from: https://www.spigotmc.org/resources/crucialapi.86380/");
+            if (!crucialLib.getDescription().getVersion().startsWith(CRUCIAL_LIB_VERSION.substring(0,3))) {
+                plugin().error("Error 24: Please update to CrucialLib " + CRUCIAL_LIB_VERSION);
+                plugin().log("Please download it from: https://github.com/ChafficPlugins/CrucialLib/releases");
                 return false;
             }
             return true;
         }
-        plugin.error("Error 26: Failed to connect to CrucialAPI.");
+        plugin().error("Error 26: Failed to connect to CrucialLib.");
         return false;
     }
 
     public static boolean isIsConnected() {
         return isConnected;
     }
-}
\ No newline at end of file
+}
diff --git a/src/main/java/de/chafficplugins/mininglevels/utils/CustomMessages.java b/src/main/java/de/chafficplugins/mininglevels/utils/CustomMessages.java
index fada0dd..51fe029 100644
--- a/src/main/java/de/chafficplugins/mininglevels/utils/CustomMessages.java
+++ b/src/main/java/de/chafficplugins/mininglevels/utils/CustomMessages.java
@@ -1,7 +1,7 @@
 package de.chafficplugins.mininglevels.utils;
 
 import de.chafficplugins.mininglevels.MiningLevels;
-import io.github.chafficui.CrucialAPI.Utils.localization.LocalizedFromYaml;
+import io.github.chafficui.CrucialLib.Utils.localization.LocalizedFromYaml;
 
 import java.io.IOException;
 
diff --git a/src/main/java/de/chafficplugins/mininglevels/utils/SenderUtils.java b/src/main/java/de/chafficplugins/mininglevels/utils/SenderUtils.java
index 872c8dd..42c8b83 100644
--- a/src/main/java/de/chafficplugins/mininglevels/utils/SenderUtils.java
+++ b/src/main/java/de/chafficplugins/mininglevels/utils/SenderUtils.java
@@ -1,7 +1,7 @@
 package de.chafficplugins.mininglevels.utils;
 
 import de.chafficplugins.mininglevels.MiningLevels;
-import io.github.chafficui.CrucialAPI.Utils.localization.Localizer;
+import io.github.chafficui.CrucialLib.Utils.localization.Localizer;
 import net.md_5.bungee.api.ChatMessageType;
 import net.md_5.bungee.api.chat.TextComponent;
 import org.bukkit.ChatColor;
diff --git a/src/main/resources/plugin.yml b/src/main/resources/plugin.yml
index fea51f8..dc9392b 100644
--- a/src/main/resources/plugin.yml
+++ b/src/main/resources/plugin.yml
@@ -1,9 +1,9 @@
 name: ${project.name}
 version: '${project.version}'
 main: de.chafficplugins.mininglevels.MiningLevels
-api-version: 1.15
+api-version: '1.21'
 prefix: MiningLevels
-softdepend: [ CrucialAPI, PlaceholderAPI ]
+softdepend: [ CrucialLib, PlaceholderAPI ]
 authors: [ ChafficPlugins ]
 description: An easily configurable advanced mining level system.
 commands:
diff --git a/src/test/java/de/chafficplugins/mininglevels/api/MiningBlockTest.java b/src/test/java/de/chafficplugins/mininglevels/api/MiningBlockTest.java
new file mode 100644
index 0000000..0fbec93
--- /dev/null
+++ b/src/test/java/de/chafficplugins/mininglevels/api/MiningBlockTest.java
@@ -0,0 +1,130 @@
+package de.chafficplugins.mininglevels.api;
+
+import org.bukkit.Material;
+import org.junit.jupiter.api.AfterAll;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.mockbukkit.mockbukkit.MockBukkit;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class MiningBlockTest {
+
+    @BeforeAll
+    static void setUpServer() {
+        MockBukkit.mock();
+    }
+
+    @AfterAll
+    static void tearDown() {
+        MockBukkit.unmock();
+    }
+
+    @BeforeEach
+    void setUp() {
+        MiningBlock.miningBlocks.clear();
+        MiningLevel.miningLevels.clear();
+        MiningLevel.miningLevels.add(new MiningLevel("Beginner", 100, 0));
+        MiningLevel.miningLevels.add(new MiningLevel("Apprentice", 300, 1));
+        MiningLevel.miningLevels.add(new MiningLevel("Expert", 500, 2));
+    }
+
+    @Test
+    void constructor_singleMaterial_shouldCreateBlock() {
+        MiningBlock block = new MiningBlock(Material.COAL_ORE, 1, 0);
+        assertNotNull(block);
+        assertEquals(1, block.getXp());
+        assertEquals(0, block.getMinLevel());
+        assertTrue(block.getMaterials().contains(Material.COAL_ORE));
+    }
+
+    @Test
+    void constructor_multipleMaterials_shouldCreateBlock() {
+        MiningBlock block = new MiningBlock(
+                new Material[]{Material.REDSTONE_ORE, Material.DEEPSLATE_REDSTONE_ORE},
+                2, 0
+        );
+        assertEquals(2, block.getMaterials().size());
+        assertTrue(block.getMaterials().contains(Material.REDSTONE_ORE));
+        assertTrue(block.getMaterials().contains(Material.DEEPSLATE_REDSTONE_ORE));
+    }
+
+    @Test
+    void constructor_nonBlockMaterial_shouldThrow() {
+        assertThrows(IllegalArgumentException.class, () ->
+                new MiningBlock(Material.DIAMOND, 1, 0));
+    }
+
+    @Test
+    void getMiningBlock_existingMaterial_shouldReturnBlock() {
+        MiningBlock block = new MiningBlock(Material.DIAMOND_ORE, 5, 2);
+        MiningBlock.miningBlocks.add(block);
+
+        MiningBlock found = MiningBlock.getMiningBlock(Material.DIAMOND_ORE);
+        assertNotNull(found);
+        assertEquals(5, found.getXp());
+        assertEquals(2, found.getMinLevel());
+    }
+
+    @Test
+    void getMiningBlock_nonExistingMaterial_shouldReturnNull() {
+        MiningBlock.miningBlocks.add(new MiningBlock(Material.COAL_ORE, 1, 0));
+
+        assertNull(MiningBlock.getMiningBlock(Material.DIAMOND_ORE));
+    }
+
+    @Test
+    void getMiningBlock_fromMultiMaterialBlock_shouldReturnBlock() {
+        MiningBlock block = new MiningBlock(
+                new Material[]{Material.IRON_ORE, Material.DEEPSLATE_IRON_ORE},
+                3, 1
+        );
+        MiningBlock.miningBlocks.add(block);
+
+        assertNotNull(MiningBlock.getMiningBlock(Material.IRON_ORE));
+        assertNotNull(MiningBlock.getMiningBlock(Material.DEEPSLATE_IRON_ORE));
+        assertEquals(block, MiningBlock.getMiningBlock(Material.IRON_ORE));
+    }
+
+    @Test
+    void setXp_shouldUpdateValue() {
+        MiningBlock block = new MiningBlock(Material.COAL_ORE, 1, 0);
+        block.setXp(10);
+        assertEquals(10, block.getXp());
+    }
+
+    @Test
+    void setMinLevel_validRange_shouldUpdateValue() {
+        MiningBlock block = new MiningBlock(Material.COAL_ORE, 1, 0);
+        block.setMinLevel(1);
+        assertEquals(1, block.getMinLevel());
+    }
+
+    @Test
+    void setMinLevel_outOfRange_shouldNotChange() {
+        MiningBlock block = new MiningBlock(Material.COAL_ORE, 1, 1);
+        // 0 is not > 0, so setMinLevel(0) won't change
+        block.setMinLevel(0);
+        assertEquals(1, block.getMinLevel());
+        // 10 >= miningLevels.size() (3), so won't change
+        block.setMinLevel(10);
+        assertEquals(1, block.getMinLevel());
+    }
+
+    @Test
+    void multipleMiningBlocks_shouldTrackSeparately() {
+        MiningBlock coal = new MiningBlock(Material.COAL_ORE, 1, 0);
+        MiningBlock iron = new MiningBlock(Material.IRON_ORE, 3, 1);
+        MiningBlock diamond = new MiningBlock(Material.DIAMOND_ORE, 5, 2);
+
+        MiningBlock.miningBlocks.add(coal);
+        MiningBlock.miningBlocks.add(iron);
+        MiningBlock.miningBlocks.add(diamond);
+
+        assertEquals(3, MiningBlock.miningBlocks.size());
+        assertEquals(coal, MiningBlock.getMiningBlock(Material.COAL_ORE));
+        assertEquals(iron, MiningBlock.getMiningBlock(Material.IRON_ORE));
+        assertEquals(diamond, MiningBlock.getMiningBlock(Material.DIAMOND_ORE));
+    }
+}
diff --git a/src/test/java/de/chafficplugins/mininglevels/api/MiningLevelTest.java b/src/test/java/de/chafficplugins/mininglevels/api/MiningLevelTest.java
new file mode 100644
index 0000000..6112687
--- /dev/null
+++ b/src/test/java/de/chafficplugins/mininglevels/api/MiningLevelTest.java
@@ -0,0 +1,227 @@
+package de.chafficplugins.mininglevels.api;
+
+import org.junit.jupiter.api.AfterAll;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.mockbukkit.mockbukkit.MockBukkit;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class MiningLevelTest {
+
+    @BeforeAll
+    static void setUpServer() {
+        MockBukkit.mock();
+    }
+
+    @AfterAll
+    static void tearDown() {
+        MockBukkit.unmock();
+    }
+
+    @BeforeEach
+    void setUp() {
+        MiningLevel.miningLevels.clear();
+        MiningLevel level0 = new MiningLevel("Beginner", 100, 0);
+        MiningLevel level1 = new MiningLevel("Apprentice", 300, 1);
+        MiningLevel level2 = new MiningLevel("Expert", 500, 2);
+        MiningLevel level3 = new MiningLevel("Master", 1000, 3);
+        MiningLevel.miningLevels.add(level0);
+        MiningLevel.miningLevels.add(level1);
+        MiningLevel.miningLevels.add(level2);
+        MiningLevel.miningLevels.add(level3);
+    }
+
+    @Test
+    void get_shouldReturnCorrectLevel() {
+        MiningLevel level = MiningLevel.get(0);
+        assertNotNull(level);
+        assertEquals("Beginner", level.getName());
+        assertEquals(0, level.getOrdinal());
+    }
+
+    @Test
+    void get_shouldReturnNullForInvalidOrdinal() {
+        assertNull(MiningLevel.get(99));
+        assertNull(MiningLevel.get(-1));
+    }
+
+    @Test
+    void getNext_shouldReturnNextLevel() {
+        MiningLevel level = MiningLevel.get(0);
+        assertNotNull(level);
+        MiningLevel next = level.getNext();
+        assertNotNull(next);
+        assertEquals("Apprentice", next.getName());
+        assertEquals(1, next.getOrdinal());
+    }
+
+    @Test
+    void getNext_atMaxLevel_shouldReturnSelf() {
+        MiningLevel maxLevel = MiningLevel.get(3);
+        assertNotNull(maxLevel);
+        MiningLevel next = maxLevel.getNext();
+        assertEquals(maxLevel, next);
+    }
+
+    @Test
+    void getBefore_shouldReturnPreviousLevel() {
+        MiningLevel level = MiningLevel.get(2);
+        assertNotNull(level);
+        MiningLevel before = level.getBefore();
+        assertNotNull(before);
+        assertEquals("Apprentice", before.getName());
+        assertEquals(1, before.getOrdinal());
+    }
+
+    @Test
+    void getBefore_atMinLevel_shouldReturnSelf() {
+        MiningLevel minLevel = MiningLevel.get(0);
+        assertNotNull(minLevel);
+        MiningLevel before = minLevel.getBefore();
+        assertEquals(minLevel, before);
+    }
+
+    @Test
+    void getNextLevelXP_shouldReturnCorrectValue() {
+        MiningLevel level = MiningLevel.get(0);
+        assertNotNull(level);
+        assertEquals(100, level.getNextLevelXP());
+    }
+
+    @Test
+    void setNextLevelXP_shouldUpdateValue() {
+        MiningLevel level = MiningLevel.get(0);
+        assertNotNull(level);
+        level.setNextLevelXP(200);
+        assertEquals(200, level.getNextLevelXP());
+    }
+
+    @Test
+    void getMaxLevel_shouldReturnLastLevel() {
+        MiningLevel maxLevel = MiningLevel.getMaxLevel();
+        assertNotNull(maxLevel);
+        assertEquals("Master", maxLevel.getName());
+        assertEquals(3, maxLevel.getOrdinal());
+    }
+
+    @Test
+    void equals_sameLevels_shouldBeEqual() {
+        MiningLevel level1 = MiningLevel.get(0);
+        MiningLevel level2 = MiningLevel.get(0);
+        assertEquals(level1, level2);
+    }
+
+    @Test
+    void equals_differentLevels_shouldNotBeEqual() {
+        MiningLevel level1 = MiningLevel.get(0);
+        MiningLevel level2 = MiningLevel.get(1);
+        assertNotEquals(level1, level2);
+    }
+
+    @Test
+    void instantBreakProbability_defaultIsZero() {
+        MiningLevel level = MiningLevel.get(0);
+        assertNotNull(level);
+        assertEquals(0, level.getInstantBreakProbability());
+    }
+
+    @Test
+    void setInstantBreakProbability_validRange() {
+        MiningLevel level = MiningLevel.get(0);
+        assertNotNull(level);
+        level.setInstantBreakProbability(50);
+        assertEquals(50, level.getInstantBreakProbability());
+    }
+
+    @Test
+    void setInstantBreakProbability_outOfRange_shouldNotChange() {
+        MiningLevel level = MiningLevel.get(0);
+        assertNotNull(level);
+        level.setInstantBreakProbability(50);
+        level.setInstantBreakProbability(101);
+        assertEquals(50, level.getInstantBreakProbability());
+        level.setInstantBreakProbability(-1);
+        assertEquals(50, level.getInstantBreakProbability());
+    }
+
+    @Test
+    void extraOreProbability_defaultIsZero() {
+        MiningLevel level = MiningLevel.get(0);
+        assertNotNull(level);
+        assertEquals(0, level.getExtraOreProbability());
+    }
+
+    @Test
+    void setExtraOreProbability_validRange() {
+        MiningLevel level = MiningLevel.get(0);
+        assertNotNull(level);
+        level.setExtraOreProbability(25);
+        assertEquals(25, level.getExtraOreProbability());
+    }
+
+    @Test
+    void setExtraOreProbability_outOfRange_shouldNotChange() {
+        MiningLevel level = MiningLevel.get(0);
+        assertNotNull(level);
+        level.setExtraOreProbability(25);
+        level.setExtraOreProbability(101);
+        assertEquals(25, level.getExtraOreProbability());
+        level.setExtraOreProbability(-1);
+        assertEquals(25, level.getExtraOreProbability());
+    }
+
+    @Test
+    void maxExtraOre_defaultIsZero() {
+        MiningLevel level = MiningLevel.get(0);
+        assertNotNull(level);
+        assertEquals(0, level.getMaxExtraOre());
+    }
+
+    @Test
+    void setMaxExtraOre_validValue() {
+        MiningLevel level = MiningLevel.get(0);
+        assertNotNull(level);
+        level.setMaxExtraOre(5);
+        assertEquals(5, level.getMaxExtraOre());
+    }
+
+    @Test
+    void setMaxExtraOre_negative_shouldNotChange() {
+        MiningLevel level = MiningLevel.get(0);
+        assertNotNull(level);
+        level.setMaxExtraOre(5);
+        level.setMaxExtraOre(-1);
+        assertEquals(5, level.getMaxExtraOre());
+    }
+
+    @Test
+    void hasteLevel_defaultIsZero() {
+        MiningLevel level = MiningLevel.get(0);
+        assertNotNull(level);
+        assertEquals(0, level.getHasteLevel());
+    }
+
+    @Test
+    void setHasteLevel_validValue() {
+        MiningLevel level = MiningLevel.get(0);
+        assertNotNull(level);
+        level.setHasteLevel(3);
+        assertEquals(3, level.getHasteLevel());
+    }
+
+    @Test
+    void setHasteLevel_negative_shouldNotChange() {
+        MiningLevel level = MiningLevel.get(0);
+        assertNotNull(level);
+        level.setHasteLevel(3);
+        level.setHasteLevel(-1);
+        assertEquals(3, level.getHasteLevel());
+    }
+
+    @Test
+    void levelListSize_shouldBeFour() {
+        assertEquals(4, MiningLevel.miningLevels.size());
+    }
+}
diff --git a/src/test/java/de/chafficplugins/mininglevels/api/MiningPlayerTest.java b/src/test/java/de/chafficplugins/mininglevels/api/MiningPlayerTest.java
new file mode 100644
index 0000000..ed3044d
--- /dev/null
+++ b/src/test/java/de/chafficplugins/mininglevels/api/MiningPlayerTest.java
@@ -0,0 +1,178 @@
+package de.chafficplugins.mininglevels.api;
+
+import org.junit.jupiter.api.AfterAll;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.mockbukkit.mockbukkit.MockBukkit;
+
+import java.util.UUID;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class MiningPlayerTest {
+
+    private UUID playerUUID;
+
+    @BeforeAll
+    static void setUpServer() {
+        MockBukkit.mock();
+    }
+
+    @AfterAll
+    static void tearDown() {
+        MockBukkit.unmock();
+    }
+
+    @BeforeEach
+    void setUp() {
+        MiningPlayer.miningPlayers.clear();
+        MiningLevel.miningLevels.clear();
+        MiningLevel.miningLevels.add(new MiningLevel("Beginner", 100, 0));
+        MiningLevel.miningLevels.add(new MiningLevel("Apprentice", 300, 1));
+        MiningLevel.miningLevels.add(new MiningLevel("Expert", 500, 2));
+        playerUUID = UUID.randomUUID();
+    }
+
+    @Test
+    void constructor_shouldCreatePlayer() {
+        MiningPlayer player = new MiningPlayer(playerUUID, 0, 0);
+        assertNotNull(player);
+        assertEquals(playerUUID, player.getUUID());
+        assertEquals(0, player.getXp());
+        assertNotNull(player.getLevel());
+        assertEquals("Beginner", player.getLevel().getName());
+    }
+
+    @Test
+    void constructor_shouldAddToStaticList() {
+        new MiningPlayer(playerUUID, 0, 0);
+        assertEquals(1, MiningPlayer.miningPlayers.size());
+    }
+
+    @Test
+    void constructor_duplicatePlayer_shouldThrow() {
+        new MiningPlayer(playerUUID, 0, 0);
+        assertThrows(IllegalArgumentException.class, () ->
+                new MiningPlayer(playerUUID, 0, 0));
+    }
+
+    @Test
+    void getMiningPlayer_existingPlayer_shouldReturn() {
+        new MiningPlayer(playerUUID, 0, 0);
+        MiningPlayer found = MiningPlayer.getMiningPlayer(playerUUID);
+        assertNotNull(found);
+        assertEquals(playerUUID, found.getUUID());
+    }
+
+    @Test
+    void getMiningPlayer_nonExistingPlayer_shouldReturnNull() {
+        assertNull(MiningPlayer.getMiningPlayer(UUID.randomUUID()));
+    }
+
+    @Test
+    void notExists_newPlayer_shouldReturnTrue() {
+        assertTrue(MiningPlayer.notExists(UUID.randomUUID()));
+    }
+
+    @Test
+    void notExists_existingPlayer_shouldReturnFalse() {
+        new MiningPlayer(playerUUID, 0, 0);
+        assertFalse(MiningPlayer.notExists(playerUUID));
+    }
+
+    @Test
+    void setXp_shouldSetWithoutLevelCheck() {
+        MiningPlayer player = new MiningPlayer(playerUUID, 0, 0);
+        player.setXp(50);
+        assertEquals(50, player.getXp());
+    }
+
+    @Test
+    void setXp_canSetAboveThreshold() {
+        MiningPlayer player = new MiningPlayer(playerUUID, 0, 0);
+        player.setXp(999);
+        assertEquals(999, player.getXp());
+    }
+
+    @Test
+    void setLevel_byOrdinal_shouldUpdateLevel() {
+        MiningPlayer player = new MiningPlayer(playerUUID, 0, 0);
+        player.setLevel(1);
+        assertEquals("Apprentice", player.getLevel().getName());
+    }
+
+    @Test
+    void setLevel_byMiningLevel_shouldUpdateLevel() {
+        MiningPlayer player = new MiningPlayer(playerUUID, 0, 0);
+        MiningLevel expert = MiningLevel.get(2);
+        assertNotNull(expert);
+        player.setLevel(expert);
+        assertEquals("Expert", player.getLevel().getName());
+    }
+
+    @Test
+    void getLevel_shouldReturnCorrectMiningLevel() {
+        MiningPlayer player = new MiningPlayer(playerUUID, 1, 50);
+        MiningLevel level = player.getLevel();
+        assertNotNull(level);
+        assertEquals("Apprentice", level.getName());
+        assertEquals(1, level.getOrdinal());
+    }
+
+    @Test
+    void equals_sameUUID_shouldBeEqual() {
+        MiningPlayer player1 = new MiningPlayer(playerUUID, 0, 0);
+        // Can't create another with same UUID (throws), so test self-equality
+        assertEquals(player1, player1);
+    }
+
+    @Test
+    void equals_differentUUID_shouldNotBeEqual() {
+        MiningPlayer player1 = new MiningPlayer(playerUUID, 0, 0);
+        MiningPlayer player2 = new MiningPlayer(UUID.randomUUID(), 0, 0);
+        assertNotEquals(player1, player2);
+    }
+
+    @Test
+    void equals_nonMiningPlayerObject_shouldReturnFalse() {
+        MiningPlayer player = new MiningPlayer(playerUUID, 0, 0);
+        assertNotEquals(player, "not a player");
+    }
+
+    @Test
+    void multiplePlayers_shouldAllBeTracked() {
+        UUID uuid1 = UUID.randomUUID();
+        UUID uuid2 = UUID.randomUUID();
+        UUID uuid3 = UUID.randomUUID();
+
+        new MiningPlayer(uuid1, 0, 0);
+        new MiningPlayer(uuid2, 1, 50);
+        new MiningPlayer(uuid3, 2, 200);
+
+        assertEquals(3, MiningPlayer.miningPlayers.size());
+        assertNotNull(MiningPlayer.getMiningPlayer(uuid1));
+        assertNotNull(MiningPlayer.getMiningPlayer(uuid2));
+        assertNotNull(MiningPlayer.getMiningPlayer(uuid3));
+    }
+
+    @Test
+    void playerWithLevel0_shouldHaveBeginnerLevel() {
+        MiningPlayer player = new MiningPlayer(playerUUID, 0, 0);
+        assertEquals("Beginner", player.getLevel().getName());
+        assertEquals(0, player.getLevel().getOrdinal());
+    }
+
+    @Test
+    void playerWithMaxLevel_shouldHaveMaxLevel() {
+        MiningPlayer player = new MiningPlayer(playerUUID, 2, 0);
+        assertEquals("Expert", player.getLevel().getName());
+    }
+
+    @Test
+    void setXp_zeroXp_shouldWork() {
+        MiningPlayer player = new MiningPlayer(playerUUID, 0, 50);
+        player.setXp(0);
+        assertEquals(0, player.getXp());
+    }
+}
diff --git a/src/test/java/de/chafficplugins/mininglevels/api/RewardTest.java b/src/test/java/de/chafficplugins/mininglevels/api/RewardTest.java
new file mode 100644
index 0000000..3fc2e18
--- /dev/null
+++ b/src/test/java/de/chafficplugins/mininglevels/api/RewardTest.java
@@ -0,0 +1,50 @@
+package de.chafficplugins.mininglevels.api;
+
+import org.bukkit.Material;
+import org.bukkit.inventory.ItemStack;
+import org.junit.jupiter.api.AfterAll;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+import org.mockbukkit.mockbukkit.MockBukkit;
+import org.mockbukkit.mockbukkit.ServerMock;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class RewardTest {
+
+    private static ServerMock server;
+
+    @BeforeAll
+    static void setUpServer() {
+        server = MockBukkit.mock();
+    }
+
+    @AfterAll
+    static void tearDown() {
+        MockBukkit.unmock();
+    }
+
+    @Test
+    void constructor_shouldStoreTypeAndAmount() {
+        ItemStack item = new ItemStack(Material.DIAMOND, 10);
+        Reward reward = new Reward(item);
+        assertEquals(10, reward.getAmount());
+    }
+
+    @Test
+    void getItemStack_shouldReturnCorrectMaterialAndAmount() {
+        ItemStack item = new ItemStack(Material.IRON_INGOT, 5);
+        Reward reward = new Reward(item);
+        ItemStack result = reward.getItemStack();
+        assertEquals(Material.IRON_INGOT, result.getType());
+        assertEquals(5, result.getAmount());
+    }
+
+    @Test
+    void getItemStack_singleItem_shouldHaveAmountOne() {
+        ItemStack item = new ItemStack(Material.EMERALD, 1);
+        Reward reward = new Reward(item);
+        assertEquals(1, reward.getAmount());
+        assertEquals(Material.EMERALD, reward.getItemStack().getType());
+    }
+}
diff --git a/src/test/java/de/chafficplugins/mininglevels/utils/ConfigStringsTest.java b/src/test/java/de/chafficplugins/mininglevels/utils/ConfigStringsTest.java
new file mode 100644
index 0000000..05c72a0
--- /dev/null
+++ b/src/test/java/de/chafficplugins/mininglevels/utils/ConfigStringsTest.java
@@ -0,0 +1,68 @@
+package de.chafficplugins.mininglevels.utils;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class ConfigStringsTest {
+
+    @Test
+    void crucialLibVersion_shouldBe300() {
+        assertEquals("3.0.0", ConfigStrings.CRUCIAL_LIB_VERSION);
+    }
+
+    @Test
+    void permissions_shouldNotBeNull() {
+        assertNotNull(ConfigStrings.PERMISSION_ADMIN);
+        assertNotNull(ConfigStrings.PERMISSION_SET_LEVEL);
+        assertNotNull(ConfigStrings.PERMISSION_SET_XP);
+        assertNotNull(ConfigStrings.PERMISSION_LEVEL);
+        assertNotNull(ConfigStrings.PERMISSION_RELOAD);
+        assertNotNull(ConfigStrings.PERMISSION_EDITOR);
+        assertNotNull(ConfigStrings.PERMISSIONS_LEADERBOARD);
+        assertNotNull(ConfigStrings.PERMISSION_DEBUG);
+    }
+
+    @Test
+    void configKeys_shouldNotBeNull() {
+        assertNotNull(ConfigStrings.LVL_UP_SOUND);
+        assertNotNull(ConfigStrings.MAX_LEVEL_XP_DROPS);
+        assertNotNull(ConfigStrings.LEVEL_WITH_PLAYER_PLACED_BLOCKS);
+        assertNotNull(ConfigStrings.LEVEL_WITH_GENERATED_BLOCKS);
+        assertNotNull(ConfigStrings.LEVEL_PROGRESSION_MESSAGES);
+        assertNotNull(ConfigStrings.DESTROY_MINING_BLOCKS_ON_EXPLODE);
+        assertNotNull(ConfigStrings.MINING_ITEMS);
+        assertNotNull(ConfigStrings.ADMIN_DEBUG);
+    }
+
+    @Test
+    void messageKeys_shouldNotBeNull() {
+        assertNotNull(ConfigStrings.NO_PERMISSION);
+        assertNotNull(ConfigStrings.NEW_LEVEL);
+        assertNotNull(ConfigStrings.PLAYER_NOT_EXIST);
+        assertNotNull(ConfigStrings.XP_RECEIVED);
+        assertNotNull(ConfigStrings.LEVEL_OF);
+        assertNotNull(ConfigStrings.LEVEL_UNLOCKED);
+        assertNotNull(ConfigStrings.LEVEL_NEEDED);
+        assertNotNull(ConfigStrings.LEVEL_DROPPED);
+        assertNotNull(ConfigStrings.XP_GAINED);
+        assertNotNull(ConfigStrings.RELOAD_SUCCESSFUL);
+        assertNotNull(ConfigStrings.ERROR_OCCURRED);
+    }
+
+    @Test
+    void prefix_shouldHaveDefaultValue() {
+        assertNotNull(ConfigStrings.PREFIX);
+        assertTrue(ConfigStrings.PREFIX.contains("ML"));
+    }
+
+    @Test
+    void localizedIdentifier_shouldBeMininglevels() {
+        assertEquals("mininglevels", ConfigStrings.LOCALIZED_IDENTIFIER);
+    }
+
+    @Test
+    void permissionAdmin_shouldBeWildcard() {
+        assertEquals("mininglevels.*", ConfigStrings.PERMISSION_ADMIN);
+    }
+}
diff --git a/src/test/java/de/chafficplugins/mininglevels/utils/MathUtilsTest.java b/src/test/java/de/chafficplugins/mininglevels/utils/MathUtilsTest.java
new file mode 100644
index 0000000..2c2f610
--- /dev/null
+++ b/src/test/java/de/chafficplugins/mininglevels/utils/MathUtilsTest.java
@@ -0,0 +1,36 @@
+package de.chafficplugins.mininglevels.utils;
+
+import org.junit.jupiter.api.RepeatedTest;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class MathUtilsTest {
+
+    @RepeatedTest(50)
+    void randomDouble_shouldReturnValueInRange() {
+        double result = MathUtils.randomDouble(0, 100);
+        assertTrue(result >= 0 && result < 100,
+                "Expected value in [0, 100), got: " + result);
+    }
+
+    @RepeatedTest(50)
+    void randomDouble_shouldReturnValueInNegativeRange() {
+        double result = MathUtils.randomDouble(-50, 50);
+        assertTrue(result >= -50 && result < 50,
+                "Expected value in [-50, 50), got: " + result);
+    }
+
+    @Test
+    void randomDouble_sameMinMax_shouldReturnMin() {
+        double result = MathUtils.randomDouble(5, 5);
+        assertEquals(5.0, result, 0.001);
+    }
+
+    @RepeatedTest(20)
+    void randomDouble_smallRange_shouldReturnValueInRange() {
+        double result = MathUtils.randomDouble(1, 3);
+        assertTrue(result >= 1 && result < 3,
+                "Expected value in [1, 3), got: " + result);
+    }
+}