Generate sortable ULIDs — 26-character Crockford base32 IDs with a millisecond timestamp prefix.
ULIDs are 26 Crockford base32 characters: a 48-bit millisecond timestamp plus 80 random bits, sortable by creation time.
How to use this tool
Generate 1–100 ULIDs at once.
Fresh ULIDs appear in the output box on every click.
Paste a ULID into the decode box to see the timestamp it was created at.
Copy the list or download it as a text file.
Formula & worked example
Timestamp 1700000000000 (2023-11-14) with fixed random bytes gives a 26-character ULID whose first 10 characters decode back to exactly 1700000000000.
Limitations — read this before you rely on it
Monotonicity within one batch is best-effort: if two ids share a millisecond, the later one is bumped above the previous one in this tool's batch generator. Across separate page loads or servers, same-millisecond ULIDs are random and only sort approximately by time. ULIDs are identifiers, not secrets.
Frequently asked questions
A Universally Unique Lexicographically Sortable Identifier: 26 Crockford base32 characters, timestamp first, so ids sort in creation order.
Use a ULID when you want ids that sort by creation time and are URL-safe and readable. Use UUIDv4 when you need the widest tool support.
Crockford base32 drops letters easily confused with digits or each other (I/L with 1, O with 0, U to avoid accidental words).
No. The timestamp is visible to anyone who decodes the id, and the random part is not a password or token.
Within a batch from this tool, yes (same-millisecond ids are bumped). Across systems, ordering is approximate, not a strict guarantee.