UUID Generator in C# / .NET — Code Examples

UUIDs (Universally Unique Identifiers) are 128-bit identifiers used as database primary keys, session tokens, and idempotency keys. UUID v4 (random) is the safe default; UUID v7 (time-ordered) is preferred for database primary keys.

C# uses Guid for UUIDs. Guid.NewGuid() generates a v4-equivalent random GUID. .NET 9 adds Guid.CreateVersion7() for time-ordered v7.

using System;

// UUID v4 — random
Guid id = Guid.NewGuid();
Console.WriteLine(id); // 550e8400-e29b-41d4-a716-446655440000

// String format variants
Console.WriteLine(id.ToString("D")); // with dashes (default)
Console.WriteLine(id.ToString("N")); // no dashes, lowercase hex
Console.WriteLine(id.ToString("B")); // {braces with dashes}
Console.WriteLine(id.ToString("P")); // (parentheses with dashes)

// Parse a UUID / GUID string (throws FormatException on invalid input)
Guid parsed = Guid.Parse("550e8400-e29b-41d4-a716-446655440000");

// Safe parse (returns bool instead of throwing)
if (Guid.TryParse("550e8400-e29b-41d4-a716-446655440000", out Guid result))
    Console.WriteLine(result);

// UUID v7 — time-ordered (.NET 9+)
// Guid id7 = Guid.CreateVersion7();
// Console.WriteLine(id7);

• Guid.NewGuid() is internally equivalent to UUID v4 — it uses a CSPRNG for random bytes.
• Guid.CreateVersion7() was added in .NET 9 and generates a time-ordered UUID suitable for database primary keys.
• Use Guid.TryParse instead of Guid.Parse when validating user input to avoid exceptions.

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