CalcBrew

UUID Generator

Generate random version 4 UUIDs or time-ordered version 7 UUIDs — one at a time or up to 500 in bulk — formatted in lowercase, uppercase, without hyphens or wrapped in braces for C#/.NET. Every ID comes from your browser’s cryptographic random generator.

0 UUIDs · version 4 · 122 random bits

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    Anatomy of a UUID

    v4: xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx  (x = random hex, y = 8/9/a/b)

    v7: tttttttt-tttt-7xxx-yxxx-xxxxxxxxxxxx  (t = Unix time in ms, 48 bits)

    Other versions exist: v1 embeds a timestamp and the machine’s MAC address (avoid — it leaks hardware identity), v3 and v5 are deterministic hashes of a name (MD5 / SHA-1) that always give the same UUID for the same input, and v6 is v1 with the timestamp bytes reordered. In practice new code needs only v4 and v7.

    Generate in code: JavaScript crypto.randomUUID(), Python uuid.uuid4(), Go uuid.New(), PostgreSQL gen_random_uuid() (v7 arrives in PostgreSQL 18), .NET Guid.NewGuid() and Guid.CreateVersion7().

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