UUID Generator

**v4** is fully random — 122 bits of entropy, no time component. Perfect for unguessable IDs like API keys, session tokens, or database primary keys where you don't want to expose creation order. **v7** (RFC 9562, 2024) embeds a 48-bit millisecond timestamp at the front, then 74 bits of random. Sorting v7 UUIDs naturally orders them by creation time — useful for database primary keys because adjacent rows land in adjacent index pages, improving INSERT performance versus v4.

v1 embeds a timestamp + a 'node' identifier (originally the MAC address) + a sequence counter. It's time-ordered like v7 but leaks the host machine's identity. Modern advice is: use v7 if you want time-sortable, use v4 if you want random. v1 is mostly legacy compatibility.

Yes when generated via `crypto.randomUUID()` or `crypto.getRandomValues()` — both call the browser's CSPRNG. This tool uses `crypto.randomUUID()` where available (modern browsers) and falls back to `crypto.getRandomValues()` otherwise. Both are suitable for security-sensitive use cases like session tokens, API keys, and password reset codes.

Browser JavaScript has no access to the MAC address — so the 'node' field is filled with random bytes (with the multicast bit set, per RFC 4122 §4.1.6, to flag it as locally-generated rather than a real MAC). The structure and time encoding are correct; only the node identifier is randomised. For applications that require a real MAC-based v1, generate them server-side.

v4 has 122 bits of randomness — the probability of generating a duplicate is negligible until you're generating billions per second for thousands of years. v7's random portion is 74 bits but the timestamp guarantees uniqueness within the same millisecond by relying on the random portion. For practical purposes both are collision-free.

Useful for seeding databases, testing, generating multiple session IDs in advance, populating test fixtures, or generating a batch of API keys to distribute. Up to 1000 at once; download as .txt for easy copy-paste into your code or scripts.

`00000000-0000-0000-0000-000000000000` — the all-zeros UUID. Sometimes used as a 'no value' or 'system' sentinel where null isn't available (e.g. a NOT NULL column in a database).

No. UUID generation is a pure JavaScript operation. Everything runs in your browser, nothing is sent to a server. The tool works fully offline once loaded.