ULID Generator
Generate ULIDs — sortable, time-prefixed IDs that play nicely with database indexes.
Quick answer: Generate ULIDs — sortable, time-prefixed IDs that play nicely with database indexes.
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Frequently asked questions
- What is a ULID?
- A 26-character ID combining a millisecond timestamp prefix with secure random bits, encoded in Crockford base32 — sortable by creation time and URL-safe.
- Why pick ULID over UUID?
- Database indexes love sortable IDs — inserts go to the end of the B-tree, not random pages, which speeds up writes and shrinks the index.
- How does monotonic mode help?
- When several ULIDs are generated in the same millisecond, monotonic mode increments the random part so order is preserved.
- Is the random source secure?
- Yes — the underlying library uses the browser's CSPRNG. Safe for primary keys and tokens.
- How long is a ULID?
- 26 characters, fixed. The first 10 are the timestamp; the last 16 are randomness.
- Is base32 case-sensitive?
- ULIDs are uppercase by convention but Crockford base32 is decoded case-insensitively, so lowercased copies still parse.
- Is anything sent to a server?
- No. Generation runs entirely in your browser.
- When should I use UUIDs instead?
- If you need to hide creation time (the prefix is decodable) or you must follow RFC 4122 specifically, UUID v4 is the right choice.
- Can I generate ULIDs on mobile?
- Yes. Phones and tablets work the same as desktops.
- Is this ULID generator free?
- Yes — free, no signup, no limits.