What is the ULID Generator?
A ULID (Universally Unique Lexicographically Sortable Identifier) is a 128-bit ID designed to be both unique and sortable. The first 48 bits store a timestamp in milliseconds and the remaining 80 bits are random. The result is encoded as 26 characters in Crockford’s Base32, which uses digits and uppercase letters while leaving out I, L, O and U to avoid confusion.
Because the timestamp comes first, ULIDs sort in the order they were created when compared as plain strings. You can see this in the output: IDs generated in the same moment share the same first ten characters, and only the random part that follows differs. That makes ULIDs a great fit for database primary keys, log entries and event streams where insertion order matters.
This generator creates up to 200 ULIDs at once using the Web Crypto API for the random component, entirely in your browser. Nothing is uploaded or stored, so you can paste the IDs straight into fixtures, migrations or test requests.
How to use the ULID Generator
- Enter How many? ULIDs you need, up to 200.
- Press Generate to create the IDs with the current timestamp.
- Copy a single ULID or the whole list.
- Export the IDs as CSV, JSON or TXT for fixtures and seed scripts.
Popular uses
- Backend developers — use time-ordered primary keys that index well in databases.
- Data engineers — tag events and log lines with sortable IDs.
- QA testers — fill ULID fields and validate parsing and ordering.
- Architects — compare ULIDs with UUIDs and other ID schemes in prototypes.
Why use RandNow?
- Instant & unlimited — no sign-up, no daily caps.
- Private by design — results are generated in your browser, not on our servers.
- Export-ready — copy, CSV, JSON and TXT downloads built in.
- Cryptographically random — powered by the Web Crypto API.
Anatomy of a ULID
In 01M5J6G12AZT9EBBQNRMXK5C00, the first 10 characters (01M5J6G12A) encode the timestamp and the last 16 characters are random. Ten Base32 characters can hold timestamps far into the future, and the 80-bit random part makes collisions within the same millisecond extremely unlikely.
ULID or UUID?
Choose a ULID when you want IDs that sort by time and stay compact. Keep in mind that the timestamp reveals roughly when each ID was created; if that matters, a fully random ID may be better. Press Generate again for a fresh set — it’s free and unlimited.
Frequently asked questions
What does ULID stand for?
Universally Unique Lexicographically Sortable Identifier — a 128-bit ID made of a 48-bit millisecond timestamp and 80 random bits.
Why do my ULIDs start with the same characters?
The first 10 characters encode the creation timestamp. IDs generated in the same moment share that prefix; the 16 random characters after it keep them unique.
Are ULIDs compatible with UUID columns?
Both are 128 bits, so a ULID can be converted to a UUID-shaped value for storage, but the text formats differ. Check your database or library for ULID support.
How many ULIDs can I generate at once?
Up to 200 per batch.