How to use it
- Pick UUID or ULID.
- Set how many to generate.
- Copy the list.
Why use it
- Generate many unique IDs at once.
- Use them for databases, tests, and APIs.
- ULID keeps IDs sortable by time.
- Secure random values from your browser.
- Free with no limits.
UUID vs. ULID
| UUID v4 | ULID | |
|---|---|---|
| Structure | 32 hex chars, 4 dashes | 26 base-32 chars |
| Sortable by time | No, completely random | Yes, time-ordered |
| Best for | Unique keys everywhere | Chronological ordering + uniqueness |
Why identifiers matter
Every row in a database and every node in a distributed system needs a unique identifier. Good identifiers should be unpredictable (to prevent guessing and enumeration attacks) and easy to generate anywhere without coordination.
- UUID v4 relies on 122 bits of randomness, so the chance of a collision is negligible even across billions of records. It is the safe default for most applications.
- ULID packs a 48-bit millisecond timestamp plus randomness into a sortable, URL-friendly string. It is a great fit for logs, event streams, and databases that benefit from roughly time-ordered primary keys for better index locality.
This generator produces both with secure randomness from your browser, and lets you generate many at once to paste straight into a fixture, seed, or test suite.