ULID generator
Creates ULIDs per the published spec: 48 bits of time and 80 random bits in Crockford Base32, shorter than a UUID and sortable as text by time.
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Processing and privacy: The result is calculated inside your browser and your data is not sent to any server.
How to use it
- Enter how many, unix time in ms (leave empty for now), monotonic within the batch and lowercase.
- The result appears straight away and updates as you edit.
- Copy the result, or copy a link that keeps the same values to share it.
How it is calculated
The first 10 characters are the Unix time in ms in Base32 (5 bits per character) and the last 16 are 80 random bits. In monotonic mode the random part is incremented by 1 within the same millisecond.
Example
Inputs: How many = 5, Monotonic within the batch = yes, Lowercase = no. Result: ULIDs: 01M69SR7MDER1GP7SM6EZH2KA4 01M69SR7MDER1GP7SM6EZH2KA5 01M69SR7MDER1GP7SM6EZH2KA6 01M69SR7MDER1GP7SM6EZH2KA7 01M69SR7MDER1GP7SM6EZH2KA8; Time (UTC): 2026-10-31T20:17:24.621Z; Count: 5.
Limits and caveats
- A ULID reveals when it was created, so avoid it where timing must stay private.
- A ULID is not in UUID format; some databases need it converted before storing it in a uuid column.
Questions about this tool
How is ULID different from UUID v7?
Both start with a 48-bit time, but a ULID is 26 Base32 characters while a UUID v7 is 36 hex characters with hyphens.
Why does a ULID never contain I, L, O or U?
Crockford Base32 leaves them out to avoid confusion with 1 and 0 and to avoid spelling words by accident.
What does monotonic mean here?
When several ids share a millisecond, the random part is incremented by 1, so the ids stay sorted in creation order.