# UUID generator

> Generate random UUIDs (GUIDs) in bulk: version 4 or time-ordered version 7, upper or lower case, with or without dashes. Copy them all at once.

Canonical: https://toolspace.tech/uuid-generator/
Last updated: 2026-10-25

Generate up to 1,000 UUIDs at once: random version 4 or time-ordered version 7. Choose upper case, no dashes or {braces}, then copy them all or download a text file.

This is an interactive tool that runs in the browser: [open the UUID generator](https://toolspace.tech/uuid-generator/) to use it. Nothing typed into it is uploaded.

## Common mistakes

### Using v4 as a database primary key at scale

Random keys land all over a B-tree index, which slows inserts on big tables. v7 keys arrive in time order and avoid that.

### Treating a v7 UUID as private

Its first 12 hex digits are the creation time in milliseconds. Anyone can read when the ID was made; the checker below shows it.

### Comparing UUIDs as case-sensitive strings

UUIDs are case-insensitive: 550E8400… and 550e8400… are the same ID. Normalise to lower case before comparing or storing.

### Storing UUIDs as 36-character text

Most databases have a native UUID type that stores the 16 bytes. Text takes more than twice the space and compares more slowly.

## How it works

1. **Pick a version and how many:** v4 is fully random. v7 starts with the current time in milliseconds, so new IDs sort after older ones.
2. **Choose the format:** Lower or upper case, with or without dashes, and with braces for the Windows GUID style. Changing the format doesn’t change the IDs.
3. **Copy or download:** Copy all of them, download a .txt with one per line, or press Regenerate for a fresh batch. Paste any UUID in the checker to see its version.

## Questions

### What is the difference between UUID v4 and v7?

Version 4 is 122 random bits. Version 7 (RFC 9562) puts a 48-bit Unix timestamp in milliseconds first, then random bits, so IDs created later sort later. That keeps database indexes compact when UUIDs are primary keys.

### Is a UUID the same as a GUID?

Yes. GUID is Microsoft’s name for the same 128-bit format. Windows tools often show it in upper case inside braces, like {3F2504E0-4F89-41D3-9A0C-0305E82C3301}; the Braces and Uppercase switches give you that form.

### Can two generated UUIDs collide?

In practice, no. With 122 random bits you would need to generate around 2.7 quintillion v4 UUIDs for a 50% chance of a single duplicate. Within one v7 batch, a counter keeps every ID in the same millisecond distinct and in order.

### Are these UUIDs random enough for secrets?

They come from crypto.getRandomValues, the browser’s secure random source. Still, a UUID is an identifier, not a password: v7 also reveals when it was made.

### Are the UUIDs saved or sent anywhere?

No. They are generated in this tab and aren’t stored; only your options are remembered in this browser.

## Related

- [Password generator](https://toolspace.tech/password-generator/)
- [Hash generator](https://toolspace.tech/hash-generator/)
- [Timestamp converter](https://toolspace.tech/unix-timestamp-converter/)
- [Mock data generator](https://toolspace.tech/mock-data-generator/)