UUID Generator
Generate secure v1 and v4 UUIDs.
Configuration
How to Use
- 1
Select Version
Choose UUID v4 for random IDs (recommended) or v1 for time-based IDs.
- 2
Set Quantity
Enter how many UUIDs you need (1-500).
- 3
Generate & Export
Click Generate, then Copy All or Download the list.
UUID Versions Explained
A UUID (universally unique identifier) is a 128-bit value written as 32 hexadecimal digits in five hyphen-separated groups (8-4-4-4-12). This tool generates version 4 or version 1 UUIDs, up to 500 at a time.
Reading a UUID
- The version is the first digit of the third group:
xxxxxxxx-xxxx-4xxx-...for v4 and-1xxx-for v1. The first digit of the fourth group is 8, 9, a or b. - Version 4 fills 122 bits with output from
crypto.getRandomValues(). The chance of a collision is small enough to ignore in practice. - Version 1 combines a 60-bit timestamp (100-nanosecond intervals since 15 October 1582), a clock sequence and a 48-bit node ID.
Choosing a version for database keys
RFC 9562 (2024), which replaces RFC 4122, keeps versions 1 and 4 and adds version 7, which starts with a Unix millisecond timestamp followed by random bits. Version 1 strings do not sort in creation order, because the low bits of the timestamp come first. Version 7 values do, which reduces index fragmentation compared with random v4 keys. This tool generates v4 and v1 only, so use a library with v7 support if you need time-ordered IDs.
Caveats
- RFC 9562 advises against assuming UUIDs are hard to guess. Don't use them as session tokens, API keys or password-reset links.
- GUID is Microsoft's name for the same format. Some Windows tools show GUIDs in uppercase inside braces.
- Where the database has a native UUID type, such as PostgreSQL's
uuid, use it. It stores 16 bytes instead of a 36-character string.