ULID Generator, Decoder and UUID Converter

What is a ULID?

A Universally Unique Lexicographically Sortable Identifier is a 128-bit identifier encoded as 26 Crockford Base32 characters. The first 48 bits store a Unix timestamp in milliseconds and the remaining 80 bits are random. Canonical ULIDs use uppercase characters and omit visually ambiguous letters.

Sorting and timestamp decoding

ULIDs sort by creation time when their canonical text representations are compared. Values generated in the same millisecond share a timestamp prefix, but independently random tails do not guarantee creation order within that millisecond.

The decoder reads the first six bytes and displays the time in UTC, local time, and Unix milliseconds. The timestamp is metadata, so do not use ULIDs when exposing approximate creation time would be undesirable.

ULID and UUID conversion

Both formats contain 128 bits. Conversion changes only the textual representation: Crockford Base32 for ULID and hexadecimal groups for UUID. A converted value is not assigned a UUID version, and converting an arbitrary UUID into ULID notation does not make its first bits a meaningful creation timestamp.

Privacy and uniqueness

Generation uses crypto.getRandomValues() in your browser and does not send identifiers to MiniUtil. Collisions are extremely unlikely with 80 random bits, but an application that requires strict monotonic ordering or centralized uniqueness guarantees should use a production library and database constraints.

The format is documented by the ULID specification. Compare it with the UUID v7 Generator for an IETF-standard time-ordered UUID, the UUID v4 Generator for random UUIDs, or the GUID Generator for .NET-style formatting.