SequentialGuid

Package	NuGet	Downloads
SequentialGuid
SequentialGuid.EntityFrameworkCore
SequentialGuid.MongoDB
SequentialGuid.NodaTime

Generate database-friendly, time-ordered UUIDs anywhere in your .NET stack — no database round-trip required.

SequentialGuid produces RFC 9562 compliant UUIDs with embedded timestamps. Generate IDs client-side — in Blazor WebAssembly, MAUI, a background worker, or a REST controller — and pass them straight through to the database. You get natural sort order (dramatically reducing clustered index fragmentation), built-in timestamp extraction (no extra CreatedAt column needed), and client-side idempotency (retry-safe inserts without a server round-trip to generate a key).

Quick Start

dotnet add package SequentialGuid

using SequentialGuid;

// RFC 9562 UUIDv7 — recommended for most applications
var id = GuidV7.NewGuid();

// Extract the embedded timestamp
DateTime? created = id.ToDateTime();

// SQL Server byte order variant
var sqlId = GuidV7.NewSqlGuid();

Packages

SequentialGuid — Core Library

The zero-dependency core package. Provides UUID generation, timestamp extraction, SQL Server byte-order conversion, and strongly-typed struct wrappers.

UUID versions included:

Class	Purpose
GuidV4	Cryptographically random UUID with guaranteed RFC 9562 version & variant bits
GuidV5	Deterministic namespace + name UUID using SHA-1 (interoperable with other languages)
GuidV7	Time-ordered UUID — 48-bit Unix ms timestamp + 26-bit monotonic counter + crypto-random bits
GuidV8Time	Time-ordered UUID — 60-bit .NET Ticks (100 ns precision) + machine/process fingerprint
GuidV8Name	Deterministic namespace + name UUID using SHA-256

Use when: You need sequential GUID generation in any .NET application — API, console, library, Blazor, MAUI, or background service.

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SequentialGuid.EntityFrameworkCore — EF Core Integration

Value converters and JSON serialization support for the SequentialGuid and SequentialSqlGuid struct types.

protected override void ConfigureConventions(ModelConfigurationBuilder configurationBuilder)
{
    configurationBuilder.AddSequentialGuidValueConverters();
}

Use when: You want to use the strongly-typed SequentialGuid / SequentialSqlGuid structs as entity properties and have EF Core transparently convert them to and from Guid database columns.

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SequentialGuid.MongoDB — MongoDB Integration

Drop-in IIdGenerator for automatic sequential Guid document IDs, plus BSON serializers for the struct types.

MongoSequentialGuidGenerator.Instance.RegisterMongoIdGenerator();
BsonSerializer.RegisterSequentialGuidSerializers();

Use when: You use MongoDB and want sequential, time-ordered GUIDs as document IDs — either raw Guid with automatic generation or the strongly-typed structs.

---

SequentialGuid.NodaTime — NodaTime Integration

Generate sequential UUIDs from NodaTime Instant, OffsetDateTime, and ZonedDateTime values, and extract embedded timestamps as Instant.

var now = SystemClock.Instance.GetCurrentInstant();
var id = GuidV7.NewGuid(now);
Instant? created = id.ToInstant();

Use when: Your application uses NodaTime for date/time handling and you want to generate or extract timestamps without converting to DateTime / DateTimeOffset.

Key Features

• RFC 9562 compliant — correct version nibble and variant bits on every UUID
• Monotonically increasing — process-global Interlocked.Increment counter ensures strict ordering under concurrency
• Zero dependencies — the core package references nothing outside the BCL
• Zero allocations on modern .NET — stackalloc, Span<T>, and [SkipLocalsInit] on .NET 8+
• Broad platform support — .NET 10 / 9 / 8, .NET Framework 4.6.2, and .NET Standard 2.0 (including Blazor WebAssembly)
• Round-trip timestamp extraction — .ToDateTime() on any Guid (V7, V8, or legacy)
• SQL Server sort-order aware — NewSqlGuid(), .ToSqlGuid(), .FromSqlGuid() handle byte-order conversion
• Strongly-typed struct wrappers — SequentialGuid and SequentialSqlGuid validate at construction and implement IComparable, IFormattable, ISpanParsable<T>, and more
• Built-in benchmarks — BenchmarkDotNet project included for measuring performance on your hardware

Contributing

Pull requests and issues are welcome. The repository uses GitHub Actions for CI — all PRs must pass the build and test suite before merging.

License

This project is licensed under the MIT License.