diff --git a/api/prisma/migrations/20250920152804_add_goal_meta_field/migration.sql b/api/prisma/migrations/20250920152804_add_goal_meta_field/migration.sql
new file mode 100644
index 00000000..38619190
--- /dev/null
+++ b/api/prisma/migrations/20250920152804_add_goal_meta_field/migration.sql
@@ -0,0 +1,6 @@
+-- AlterTable
+ALTER TABLE "Goal" ADD COLUMN     "meta" JSONB;
+
+-- Add constraint to limit meta JSON size to 1024 characters
+ALTER TABLE "Goal" ADD CONSTRAINT "Goal_meta_size_check" 
+CHECK ("meta" IS NULL OR LENGTH("meta"::text) <= 4096);
diff --git a/api/prisma/schema.prisma b/api/prisma/schema.prisma
index 9ddf7451..9f95543d 100644
--- a/api/prisma/schema.prisma
+++ b/api/prisma/schema.prisma
@@ -17,6 +17,7 @@ model Goal {
   oldCategories String[]
   categories    Category[]    @relation("GoalCategories")
   difficulty    Int?
+  meta          Json?
   game          Game          @relation(fields: [gameId], references: [id])
   variants      GoalVariant[]
   createdAt     DateTime      @default(now())
diff --git a/api/src/routes/goals/Goals.ts b/api/src/routes/goals/Goals.ts
index d62d802d..36ee191e 100644
--- a/api/src/routes/goals/Goals.ts
+++ b/api/src/routes/goals/Goals.ts
@@ -4,6 +4,7 @@ import { deleteGoal, editGoal, gameForGoal } from '../../database/games/Goals';
 import upload from './Upload';
 import goalCategories from './GoalCategories';
 import { Prisma } from '@prisma/client';
+import { validateGoalMeta } from '../../util/GoalValidation';
 
 const goals = Router();
 
@@ -31,16 +32,26 @@ goals.post('/:id', async (req, res) => {
     }
 
     const { id } = req.params;
-    const { goal, description, categories, difficulty } = req.body;
+    const { goal, description, categories, difficulty, meta } = req.body;
 
-    if (!goal && description === undefined && !categories && !difficulty) {
+    if (!goal && description === undefined && !categories && !difficulty && meta === undefined) {
         res.status(400).send('No changes submitted');
         return;
     }
 
+    // Validate meta data if provided
+    if (meta !== undefined) {
+        const metaValidation = validateGoalMeta(meta);
+        if (!metaValidation.valid) {
+            res.status(400).json({ error: metaValidation.error });
+            return;
+        }
+    }
+
     const input: Prisma.GoalUpdateInput = {
         goal,
         description,
+        meta,
     };
 
     if (difficulty === 0) {
diff --git a/api/src/tests/GoalValidation.test.ts b/api/src/tests/GoalValidation.test.ts
new file mode 100644
index 00000000..9b1c13e8
--- /dev/null
+++ b/api/src/tests/GoalValidation.test.ts
@@ -0,0 +1,189 @@
+import { validateGoalMeta } from '../util/GoalValidation';
+
+describe('GoalValidation', () => {
+  describe('validateGoalMeta', () => {
+    it('should allow null and undefined values', () => {
+      expect(validateGoalMeta(null)).toEqual({ valid: true });
+      expect(validateGoalMeta(undefined as any)).toEqual({ valid: true });
+    });
+
+    it('should allow simple valid objects', () => {
+      const validMeta = {
+        type: 'auto-track',
+        config: { enabled: true },
+        tags: ['important', 'urgent']
+      };
+      expect(validateGoalMeta(validMeta)).toEqual({ valid: true });
+    });
+
+    it('should reject objects that exceed byte size limit', () => {
+      // Create a large string that exceeds 4096 bytes
+      const largeString = 'x'.repeat(5000);
+      const largeMeta = { data: largeString };
+      
+      const result = validateGoalMeta(largeMeta);
+      expect(result.valid).toBe(false);
+      expect(result.error).toContain('exceeds maximum size of 4096 bytes');
+    });
+
+    it('should allow deeply nested objects under byte limit', () => {
+      // Create a deeply nested object that's still under byte limit
+      function makeDeepObject(depth: number) {
+        let obj: any = {};
+        let cur = obj;
+        for (let i = 0; i < depth; i++) {
+          cur.a = {};
+          cur = cur.a;
+        }
+        return obj;
+      }
+
+      const deepObject = makeDeepObject(10); // Deep but small
+      const result = validateGoalMeta(deepObject);
+      
+      expect(result.valid).toBe(true);
+    });
+
+    it('should reject objects with dangerous prototype pollution keys', () => {
+      // Create object with dangerous key using Object.defineProperty to bypass JS filtering
+      const dangerousMeta: any = { normal: 'value' };
+      Object.defineProperty(dangerousMeta, '__proto__', {
+        value: { isAdmin: true },
+        enumerable: true,
+        configurable: true
+      });
+      
+      const result = validateGoalMeta(dangerousMeta);
+      expect(result.valid).toBe(false);
+      expect(result.error).toContain('contains forbidden key "__proto__"');
+    });
+
+    it('should reject objects with prototype key', () => {
+      const dangerousMeta = {
+        prototype: { isAdmin: true },
+        normal: 'value'
+      };
+      
+      const result = validateGoalMeta(dangerousMeta);
+      expect(result.valid).toBe(false);
+      expect(result.error).toContain('contains forbidden key "prototype"');
+    });
+
+    it('should reject objects with constructor key', () => {
+      const dangerousMeta = {
+        constructor: { isAdmin: true },
+        normal: 'value'
+      };
+      
+      const result = validateGoalMeta(dangerousMeta);
+      expect(result.valid).toBe(false);
+      expect(result.error).toContain('contains forbidden key "constructor"');
+    });
+
+    it('should reject objects with toString key', () => {
+      const dangerousMeta = {
+        toString: 'hacked',
+        normal: 'value'
+      };
+      
+      const result = validateGoalMeta(dangerousMeta as any);
+      expect(result.valid).toBe(false);
+      expect(result.error).toContain('contains forbidden key "toString"');
+    });
+
+    it('should reject objects with valueOf key', () => {
+      const dangerousMeta = {
+        valueOf: 'hacked',
+        normal: 'value'
+      };
+      
+      const result = validateGoalMeta(dangerousMeta as any);
+      expect(result.valid).toBe(false);
+      expect(result.error).toContain('contains forbidden key "valueOf"');
+    });
+
+    it('should handle arrays correctly', () => {
+      const arrayMeta = {
+        items: [1, 2, 3, { nested: true }],
+        count: 4
+      };
+      
+      expect(validateGoalMeta(arrayMeta)).toEqual({ valid: true });
+    });
+
+    it('should handle deeply nested arrays', () => {
+      const deepArray = [[[[[['deep']]]]]]; // 6 levels deep
+      const result = validateGoalMeta(deepArray);
+      
+      expect(result.valid).toBe(true); // No depth limit, only byte limit
+    });
+
+    it('should reject non-JSON-serializable data', () => {
+      // Create truly non-serializable data with circular reference
+      const nonSerializable: any = {
+        normal: 'value'
+      };
+      nonSerializable.self = nonSerializable; // Circular reference
+      
+      const result = validateGoalMeta(nonSerializable);
+      expect(result.valid).toBe(false);
+      expect(result.error).toContain('Invalid JSON data for goal meta');
+    });
+
+    it('should handle circular references gracefully', () => {
+      const circular: any = { name: 'test' };
+      circular.self = circular;
+      
+      const result = validateGoalMeta(circular);
+      expect(result.valid).toBe(false);
+      expect(result.error).toContain('Invalid JSON data for goal meta');
+    });
+  });
+
+  // Removed analyzeGoalMeta tests - function no longer exists
+
+  describe('Depth Bomb Attack Simulation', () => {
+    it('should handle depth bomb with recursive traversal (safe for 4KB payloads)', () => {
+      // Create a depth bomb that would crash recursive implementations
+      function makeDepthBomb(depth: number) {
+        let obj: any = {};
+        let cur = obj;
+        for (let i = 0; i < depth; i++) {
+          cur.a = {};
+          cur = cur.a;
+        }
+        return obj;
+      }
+
+      // Test with a depth that would cause stack overflow in recursive implementations
+      const depthBomb = makeDepthBomb(500); // Deep but under byte limit
+      const json = JSON.stringify(depthBomb);
+      
+      // Verify it's under byte limit
+      expect(Buffer.byteLength(json, 'utf8')).toBeLessThan(4096);
+      
+      // Our recursive implementation should handle this gracefully for 4KB payloads
+      const result = validateGoalMeta(depthBomb);
+      expect(result.valid).toBe(true); // Valid because under byte limit
+    });
+
+    it('should handle wide but shallow objects', () => {
+      // Create an object with many properties but shallow depth
+      const wideObject: any = {};
+      for (let i = 0; i < 100; i++) {
+        wideObject[`prop${i}`] = `value${i}`;
+      }
+      
+      // Should be valid (no property count limit, shallow depth)
+      expect(validateGoalMeta(wideObject)).toEqual({ valid: true });
+    });
+
+    it('should handle large arrays', () => {
+      // Create a large array (no array length limit) but keep it under byte limit
+      const largeArray = new Array(100).fill(0).map((_, i) => ({ id: i, value: `item${i}` }));
+      
+      // Should be valid (no array length limit)
+      expect(validateGoalMeta(largeArray)).toEqual({ valid: true });
+    });
+  });
+});
diff --git a/api/src/util/GoalValidation.ts b/api/src/util/GoalValidation.ts
new file mode 100644
index 00000000..ecb741b2
--- /dev/null
+++ b/api/src/util/GoalValidation.ts
@@ -0,0 +1,81 @@
+import { Prisma } from '@prisma/client';
+
+const MAX_BYTES = 4096; // measure bytes, not string length
+
+export interface GoalMetaValidationResult {
+  valid: boolean;
+  error?: string;
+}
+
+const DANGEROUS_KEYS = new Set([
+  '__proto__',     // Direct prototype access
+  'prototype',     // Constructor prototype  
+  'constructor',   // Constructor function
+  'toString',      // Could override object stringification
+  'valueOf'        // Could override object value conversion
+]);
+
+/**
+ * Check for dangerous keys in the meta object.
+ * Simple recursive check - safe for 4KB payloads.
+ */
+function checkDangerousKeys(meta: Prisma.JsonValue): string | null {
+  if (meta === null || meta === undefined || typeof meta !== 'object') {
+    return null;
+  }
+
+  if (Array.isArray(meta)) {
+    // Check array elements
+    for (const item of meta) {
+      const result = checkDangerousKeys(item);
+      if (result) return result;
+    }
+  } else {
+    // Check object keys
+    for (const [key, value] of Object.entries(meta) as [string, Prisma.JsonValue][]) {
+      if (DANGEROUS_KEYS.has(key)) {
+        return `Goal meta contains forbidden key "${key}"`;
+      }
+      // Recursively check nested values
+      const result = checkDangerousKeys(value);
+      if (result) return result;
+    }
+  }
+
+  return null;
+}
+
+/**
+ * Validate meta with all guards and early exits.
+ */
+export function validateGoalMeta(meta: Prisma.JsonValue): GoalMetaValidationResult {
+  // Allow null/undefined values
+  if (meta === null || meta === undefined) {
+    return { valid: true };
+  }
+
+  try {
+    // Convert to JSON and measure bytes (UTF-8)
+    const json = JSON.stringify(meta); // also ensures it's JSON-serializable
+    const bytes = Buffer.byteLength(json, 'utf8');
+
+    if (bytes > MAX_BYTES) {
+      return {
+        valid: false,
+        error: `Goal meta exceeds maximum size of ${MAX_BYTES} bytes (got ${bytes})`,
+      };
+    }
+
+    const dangerousKeyError = checkDangerousKeys(meta);
+    if (dangerousKeyError) {
+      return { valid: false, error: dangerousKeyError };
+    }
+
+    return { valid: true };
+  } catch (error) {
+    return {
+      valid: false,
+      error: `Invalid JSON data for goal meta: ${error instanceof Error ? error.message : 'Unknown error'}`,
+    };
+  }
+}
\ No newline at end of file
diff --git a/schema/schemas/Goal.json b/schema/schemas/Goal.json
index 3f9a2033..8ade8419 100644
--- a/schema/schemas/Goal.json
+++ b/schema/schemas/Goal.json
@@ -9,6 +9,11 @@
         "goal": {"type": "string"},
         "description": {"type": ["string", "null"]},
         "difficulty": {"type": ["number", "null"]},
-        "categories": {"type": "array", "items": {"type": "string"}}
+        "categories": {"type": "array", "items": {"type": "string"}},
+        "meta": {
+            "type": ["object", "null"],
+            "description": "Optional metadata for goal auto-tracking and additional properties",
+            "additionalProperties": true
+        }
     }
 }
\ No newline at end of file