UUID Generator
Create UUID v4 or v7 identifiers in bulk, generated on your device with a secure random source.
- generated
- 5
Output
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Your files stay on your device
This tool runs entirely in your browser. What you paste is processed on your device and is never sent to a server, so it is safe to use with tokens, keys and unpublished text.
Example
Example: five v7 keys for an orders table, and the time written inside them
A developer seeding an orders table wants primary keys that sort in the order rows are created, so new rows go to the end of the index. Settings: v7 (time-ordered), uppercase off. Three keys made in one click at 14:30:00.000 UTC on 21 October 2026, one a millisecond later, one a second later.
- The first 12 hex digits are the milliseconds since 1 January 1970: 01a15ede7640 = 1,792,593,000,000 = 21 Oct 2026, 14:30:00.000 UTC (15:30 in London).
- The 13th digit is the version, 7. The first digit of the fourth group is 8, 9, a or b, the variant. The rest is random.
- Within one millisecond the generator counts up from the previous key, so even three keys from the same instant come out in order.
| UUID (v7) | Time inside (UTC) |
|---|---|
| 01a15ede-7640-74a6-b72f-e6a78c2938fd | 14:30:00.000 |
| 01a15ede-7640-74a6-b72f-e6a78c29b1e5 | 14:30:00.000 |
| 01a15ede-7640-74a6-b72f-e6a78c2a043a | 14:30:00.000 |
| 01a15ede-7641-77ce-944e-e3d5d2c4283e | 14:30:00.001 |
| 01a15ede-7a28-733f-bee1-079cfaf93165 | 14:30:01.000 |
Sorted as plain text, the keys are already in creation order, which is what keeps a B-tree index from fragmenting. Yours will differ: the time comes from your device’s clock and the tail is random. A v4 key such as 7fb74562-981b-440c-b23d-0f879fb7105f has a 4 in the same place and no time in it.
How it works
- Choose the version: v4 for fully random identifiers, v7 for identifiers that sort by creation time.
- Set how many you need, from 1 to 500. Each one is generated independently.
- Turn on Uppercase if your codebase or database convention expects capital hexadecimal letters.
- Press Generate UUIDs, then copy the list. Each UUID is on its own line, ready to paste into a fixture, a spreadsheet or a migration.
Frequently asked questions
- What is the difference between UUID v4 and v7?
- v4 is 122 bits of pure randomness. v7 (RFC 9562) starts with a 48-bit Unix millisecond timestamp followed by random bits, so UUIDs created later sort after earlier ones. That makes v7 a much better primary key for databases like PostgreSQL or MySQL, where random v4 keys fragment B-tree indexes.
- How random are these UUIDs?
- They are generated with crypto.getRandomValues, the browser's cryptographically secure random number generator, and with crypto.randomUUID where available. They are not produced with Math.random.
- Can two generated UUIDs collide?
- For v4 the chance is astronomically small: you would need to generate about 2.7 quintillion UUIDs to reach a 50 percent probability of one duplicate. v7 additionally embeds the timestamp, so collisions would also require the same millisecond.
- Does a v7 UUID reveal when it was created?
- Yes, the first 48 bits are the creation time in milliseconds. If exposing creation time is a problem, for example in public URLs, use v4 instead.
- How do I read the creation time out of a v7 UUID?
- Remove the hyphens, take the first 12 hex digits and read them as a number: that is milliseconds since 1 January 1970, UTC. In JavaScript, new Date(parseInt(id.replace(/-/g, "").slice(0, 12), 16)); 01a15ede7640 gives 21 October 2026, 14:30:00 UTC.
- Are UUIDs made in the same millisecond still in order?
- Yes, within one list. When the clock has not moved on, the next v7 key takes the previous one’s random part plus one plus a little randomness, so a batch of 500 made in an instant sorts in the order it was generated. v4 keys have no order at all.
- Are the UUIDs generated on a server and logged?
- No. They are created in your browser and are never sent anywhere. Nouplo has no record of the identifiers you generate.
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