UUID Generator
Generate cryptographically random UUIDs (v4) or timestamp-prefixed UUIDs (v7, ideal for B-tree indexes). All generation happens client-side — your IDs never touch our servers.
Version
Format
v4 vs v7 — which should I use?
v4 is the classic choice: 122 bits of randomness. Effectively impossible to collide, no information leak, but ordering them is random — which causes B-tree fragmentation in databases at scale.
v7 (RFC 9562, 2024) prefixes the UUID with a Unix millisecond timestamp. The first 48 bits sort lexicographically by creation time — perfect for primary keys in modern Postgres/MySQL. Use this for new systems unless you have a specific reason not to.
NIL is the all-zeros UUID, used as a sentinel value. Generated as a constant — useful when you need a "missing" UUID in tests.
Frequently asked questions
Are these v4 UUIDs really random?
Yes. v4 UUIDs are generated from your browser's cryptographically secure random source, giving 122 bits of randomness — collisions are effectively impossible, and no information is encoded in the value.
Should I use v4 or v7?
Use v4 random UUIDs when you just need a unique identifier with no ordering. Choose v7 when you want IDs that sort by creation time — its leading timestamp avoids the B-tree index fragmentation that random v4 keys cause in databases.
Can I generate many UUIDs at once?
Yes. Use the count slider to produce up to 100 UUIDs in one go, then apply uppercase, no-hyphens, or quoted formatting and copy them all with a single click.
Are my UUIDs sent to a server?
No. Every UUID is generated locally in your browser and never leaves your device — safe to use for production keys and secrets.
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