UUID Generator
Generate random v4 UUIDs, time-ordered v7, name-based v5 and v3, v1 or ULIDs – one or 10,000 at a time, in the format your code needs. Decode any UUID too.
- v4 · v7 · v1 · v5 · v3 · ULID
- Up to 10,000 at once
- Secure random
- Runs in your browser
Generated in your browser with its secure random generator – nothing is sent or stored.
Decode or validate a UUID
How to generate UUIDs
- Pick a versionv4 is random and fits most uses. v7 sorts by creation time – good for database keys. v5 always gives the same UUID for the same name.
- Choose how many and the formatUp to 10,000 at once, as standard, UPPER CASE, no hyphens, {GUID}, URN, a JSON array or a SQL list.
- Copy or downloadCopy them all, or download a .txt or .csv file. Paste any UUID in the decoder to check it.
UUID versions compared
| Version | Built from | Sortable by time | Good for |
|---|---|---|---|
| v4 | 122 random bits | No | General IDs, tokens in URLs, test data |
| v7 | Unix time in ms + random | Yes | Database primary keys, event IDs, logs |
| v1 | Time in 100 ns steps + node | Partly | Older systems that expect v1 |
| v5 | SHA-1 of namespace + name | No | Stable IDs for URLs, domains or records |
| v3 | MD5 of namespace + name | No | Legacy name-based IDs (prefer v5) |
| ULID | 48-bit ms time + 80 random bits | Yes | Short, URL-safe, sortable IDs |
The version is the first digit of the third group: in xxxxxxxx-xxxx-7xxx-xxxx-xxxxxxxxxxxx it’s 7. The first digit of the fourth group is 8, 9, a or b for standard UUIDs.
Frequently asked questions
What is a UUID?
A universally unique identifier: a 128-bit number usually written as 32 hex digits in five groups, like 3f2b8c1e-9d4a-4b7e-a1c2-5e6f7a8b9c0d. Microsoft calls them GUIDs – they’re the same thing.
Which version should I use?
Version 4 for general-purpose random IDs. Version 7 for database primary keys: it starts with a timestamp, so new rows are inserted in order, which keeps indexes efficient. Version 5 when the same input must always give the same ID, such as an ID for a URL.
Can two random UUIDs be the same?
In practice, no. A v4 UUID has 122 random bits. You would need to generate about 2.7 quintillion of them before there is even a 50% chance of one duplicate.
Are these UUIDs secure?
They’re generated with your browser’s cryptographically secure random generator (crypto.getRandomValues). Even so, UUIDs are identifiers, not secrets – don’t use them as passwords or access tokens on their own.
What’s the difference between v7 and ULID?
Both put a millisecond timestamp first so they sort by time. A v7 UUID is a standard 36-character UUID (RFC 9562) that works in UUID database columns. A ULID is 26 characters in Crockford base32 – shorter and URL-friendly, but stored as text unless converted.
Does the v1 UUID reveal my MAC address?
No. This tool uses a random node ID with the multicast bit set, as the standard allows, instead of a network card address.
Is anything sent to a server?
No. UUIDs are generated in your browser and nothing is stored.
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