Free · No sign-up · Runs in browser

UUID Generator

Generate v4 (random), v7 (time-ordered), or nil UUIDs — up to 1000 at a time. Uses the browser's cryptographic PRNG; nothing is logged or stored.

0 UUIDs✓ V4
// Click Generate to produce UUIDs…

About the UUID Generator

This free online UUID generator produces universally unique identifiers in your browser using crypto.getRandomValues, the same CSPRNG the browser uses for TLS keys. Supports UUID v4 (122-bit random, RFC 4122) and the newer v7 (RFC 9562, 2024) which embeds a millisecond timestamp for natural sortability. Generate up to 1000 at a time with uppercase and brace-style options.

UUID v4 vs v7

  • v4 — fully random. Ubiquitous. Downsides: non-sortable; scatters B-tree index inserts, which hurts database performance at scale.
  • v7 — millisecond timestamp + randomness. Monotonic. Inserts cluster at the end of the index, keeping Postgres and MySQL happy. Use for new primary keys.
  • Nil UUID — 00000000-0000-0000-0000-000000000000. Reserved as a sentinel; sometimes needed for seed data or default values.

Common Use Cases

  • Primary keys for new database rows
  • Correlation IDs for distributed tracing (OpenTelemetry, Jaeger)
  • Session tokens, idempotency keys, request IDs
  • Public-facing identifiers that must not expose row counts
  • Deduplication keys for event streams

Frequently Asked Questions

Is this cryptographically secure?

Yes — v4 uses crypto.getRandomValues, which is a CSPRNG. The chance of a collision in a 122-bit v4 UUID is effectively zero even after generating billions of them.

Should I use v4 or v7?

For new systems — v7. For legacy compatibility, URLs you cannot change, or ecosystems that still default to v4 (most ORMs today) — v4. Both are valid RFC-standardized UUIDs.

Does my data leave the browser?

No. UUIDs are generated locally; nothing is sent to a server, logged, or stored. Safe for API keys and tokens.

Related Tools

Encode UUIDs to compact Base64 with our UUID ↔ Base64 tool, or read the UUID vs NanoID vs ULID guide for picking the right ID format.

v4 and v7

RFC-standard random and time-ordered UUIDs, with nil as a sentinel option.

Batch up to 1000

Generate large batches in one click for seed data, tests, and migrations.

CSPRNG

Powered by crypto.getRandomValues — same primitive used for TLS keys.