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UUID Generator

Generate cryptographically secure UUID v4 in bulk.

Generate cryptographically secure UUID v4 in bulk

UUID v4 is a 128-bit identifier with 122 random bits — collision probability is so low (about 1 in 2.71 × 10¹⁸) that you can treat them as globally unique without coordination. This generator uses crypto.randomUUID() when available and falls back to crypto.getRandomValues with the proper version/variant bits set, so the output is suitable for production use as primary keys, idempotency keys, request IDs, or session tokens.

v4 vs v7 vs ULID

v4 is fully random. v7 (the new draft RFC) embeds a millisecond timestamp prefix so IDs sort chronologically — better for database index locality. ULIDs are similar to v7 but use Crockford Base32. For most apps, v4 is fine; for high-write databases, look into v7 or ULID.

Output options

Uppercase — for systems that expect canonical uppercase form.
No dashes — 32 hex characters, useful for compact storage or URLs.

Privacy

UUIDs are generated with the Web Crypto API in your browser. Nothing is sent to a server.

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FAQ

Is UUID v4 truly unique?

Practically yes. With 122 random bits the probability of collision is astronomically low — a billion UUIDs per second for a hundred years has roughly a 50% chance of one collision.

Can I use this output in production?

Yes. We use crypto.randomUUID / getRandomValues which are cryptographically secure RNGs.

Why no UUID v1 or v3/v5?

v1 leaks MAC addresses and timestamps. v3/v5 are namespace-based and rarely needed in app code. We default to v4 because it covers 95% of real use cases.