UUID Generator — what it does
Generates UUIDs — v4 random and v7 time-ordered — using the browser's crypto source, one or many at a time. Built for developers minting database keys, request IDs, file names and trace identifiers who want standards-correct output without pulling a library for one value.
How to use UUID Generator
- Pick the version: v4 (random) is the default; v7 is time-sortable.
- Set how many you need — bulk mode generates a list.
- Copy individually or copy all.
- For database primary keys, prefer v7 when insert-order matters; otherwise v4 is fine.
- Lowercase output is standard; the tool keeps it that way.
Worked example: v4 vs v7 in a database
Ten thousand v4 keys as primary keys scatter across your B-tree and wreck insert locality; the same rows keyed by v7 insert in time order because v7 embeds a millisecond timestamp. Generating both lists here makes the difference visible — v7 values share their leading digits this second, v4 never do.
At a glance
| Versions | v4 (crypto-random) and v7 (Unix-ms timestamp + random) |
|---|---|
| Bulk | Generate many at once with a copy-all button |
| Source | crypto.getRandomValues — cryptographically strong randomness |
| Privacy | Generation is local; identifiers are never transmitted |
| Limits | No name-based (v3/v5) UUIDs — those need a namespace input and a different use case |
Frequently asked questions
- What is UUID Generator?
- Generate v4 UUIDs — one, many, or in bulk for tests and seeds.
- Is UUID Generator free to use?
- Yes — UUID Generator is free to use, with no sign-up, no install and no account.
- Does UUID Generator upload or store my data?
- No — UUID Generator runs entirely in your browser, so your text, files and results never leave your device.
- Do I need to install anything to use UUID Generator?
- No — it works in any modern browser (Chrome, Edge, Firefox, Safari) with no downloads, accounts or plugins.
- When should I choose v7 over v4?
- When the UUID becomes a database key or anything sorted by creation time. v7's timestamp prefix keeps recent rows adjacent, which improves index locality; v4's total randomness fragments it.
- Can two generated UUIDs ever collide?
- Practically no. v4 has 122 random bits — you would need to generate billions per second for centuries to expect one collision. It is safe to treat them as unique.
- Are these safe to use in public URLs?
- Yes for uniqueness, but a UUID is not a secret: anyone holding one can use it. If access control depends on the ID being unguessable, pair it with real authentication.