GENERATORS

ULID Generator

Generate sortable 26-character ULIDs (48-bit timestamp + 80-bit randomness, Crockford Base32) — bulk, monotonic, custom timestamp — and decode any ULID back to its date and randomness.

What a ULID is

A ULID is a 128-bit identifier written as 26 Crockford Base32 characters. The first 10 characters encode a 48-bit Unix millisecond timestamp; the remaining 16 encode 80 bits of randomness. Because the timestamp is first and Base32 preserves order, ULIDs sort by creation time as plain strings.

Monotonic mode

Within a single millisecond, plain ULIDs are only randomly ordered. Monotonic mode keeps the random component and increments it by one for each ULID generated in the same millisecond, so a burst of IDs stays strictly increasing.

Decoding

Any valid ULID can be read back: the tool decodes the timestamp to an exact date and shows the 80-bit random part. It also normalises the Crockford alphabet, accepting I/L as 1 and O as 0.

ULID vs UUIDv7

Both are time-ordered. UUIDv7 is 36 characters with hyphens and is an IETF standard; a ULID is shorter (26 chars, no hyphens) and Base32. Use whichever your stack supports.

Privacy

Everything runs in your browser. Nothing is sent anywhere.

FAQ

Frequently asked questions

Are ULIDs really sortable?

Yes — as strings. The timestamp is the leading portion and Crockford Base32 keeps byte order, so string sorting is time sorting (to the millisecond).

Is the randomness secure?

It comes from crypto.getRandomValues, the browser CSPRNG. A ULID is an identifier, not a secret, but the random part is genuinely unpredictable.

What is monotonic mode for?

When you generate many ULIDs in the same millisecond and need them strictly increasing, monotonic mode increments the random field instead of re-rolling it.

Can I decode a ULID made elsewhere?

Yes. Paste it into the decoder and it shows the embedded timestamp, the date, and the random component.

Is anything uploaded?

No. Generation and decoding are entirely local.