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UUID Generator

Generate v4 UUIDs in bulk

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About UUID Generator

Generates v4 UUIDs using `crypto.getRandomValues()` — the same source of entropy your OS uses. Not Math.random(), not a predictable sequence. Format: `xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx`. The 4 is fixed (version), the y can be 8, 9, a, or b (variant). Everything else is random. 122 bits of randomness per UUID. Generate one, or generate 50 at once for seeding databases or test fixtures. Click any UUID to copy it.

Common Use Cases

  • →Primary keys for database records when auto-increment is not appropriate
  • →Unique identifiers in distributed systems where coordination is not possible
  • →Correlation IDs for tracing requests across services
  • →Unique filenames for uploaded files to avoid collisions

Frequently Asked Questions

GUID vs UUID — same thing?+
Yes. GUID is Microsoft's name for the same RFC 4122 concept. They are technically identical.
How unique is "unique"?+
122 random bits per UUID. The probability of two colliding is roughly 1 in 5.3×10³⁶. You would need to generate a billion UUIDs per second for 85 years to have a 50% chance of a single collision. Treat them as unique.
UUID vs auto-increment ID — when to use which?+
Auto-increment is simpler and more compact. UUIDs make sense when: IDs are generated across multiple services without coordination, sequential IDs would leak information (e.g. order count), or you are merging data from multiple sources.
v1 vs v4 — what is the difference?+
v1 is derived from the current timestamp and MAC address — predictable and potentially privacy-leaking. v4 is entirely random. Use v4 unless you specifically need the timestamp properties of v1.