ULID Generator & Decoder
Generate ULIDs — Universally Unique Lexicographically Sortable Identifiers — and decode them back to their timestamp. A ULID is 128 bits encoded as 26 Crockford-Base32 characters: a 48-bit Unix-millisecond timestamp (10 chars) followed by 80 bits of cryptographic randomness (16 chars). Because the timestamp leads and the alphabet is monotonic, ULIDs sort lexicographically in time order — handy for database keys and event logs. Toggle monotonic generation so that within the same millisecond each ID is strictly greater than the last. Everything runs locally in your browser; randomness comes from the Web Crypto API.
Generate
Decode a ULID
ULID (Universally Unique Lexicographically Sortable Identifier) is a 128-bit identifier encoded in 26 characters of Crockford Base32 (0-9 A-Z excluding I L O U to avoid ambiguity). The first 10 chars are a 48-bit Unix time in milliseconds; the last 16 are 80 bits of randomness. Because the time occupies the most-significant positions and the alphabet sorts naturally, two ULIDs generated in increasing milliseconds compare the same way as strings — so a plain string sort orders them chronologically. Monotonic mode guarantees strict ordering even within a single millisecond by incrementing the random portion instead of re-rolling it. ULIDs are case-insensitive on decode and are a popular sortable alternative to UUID v4. Pairs with the UUID Generator. Everything runs locally — nothing leaves your browser.