UUID Generator
Generate v4 UUIDs
What is a UUID?
A UUID (Universally Unique Identifier) is a 128-bit value usually shown as 32 hex digits in the form `xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx`. The collision probability between independently generated UUIDs is so low it's treated as zero — billions of UUIDs can be generated by independent systems without coordination.
Version 4 UUIDs (the most common) are random: 122 of the 128 bits are filled with cryptographic randomness. Use them as primary keys, request IDs, file identifiers, or anywhere you need a unique value without a central authority issuing them.
Common use cases
- Database primary keys — replaces auto-increment IDs in distributed systems.
- Request / trace IDs — log a UUID per inbound request to correlate logs across services.
- Idempotency keys — pass a UUID with API requests so retries don't double-process.
- File names — `${uuid}.png` avoids collisions in a shared upload bucket.
Frequently asked questions
Is UUID v4 truly unique?
Effectively yes. The collision probability for 1 billion UUIDs is about 1 in 18 trillion — small enough that engineering teams treat collisions as impossible.
UUID v4 vs v7?
v4 is fully random — good for general use. v7 (newer) embeds a timestamp prefix, so UUIDs sort in creation order — better for database indexing. This tool generates v4.
How does it differ from a random string?
UUID is a standard format — every language and database has built-in parsing/storage for it. A custom random string works but lacks the ecosystem support.
Can I generate many at once?
Yes — set the count and the tool emits a list. Up to several thousand without slowing the browser.
Is the randomness sent to the server?
No. UUIDs are generated by `crypto.randomUUID` running in your browser; nothing leaves your device.