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UUID and ULID Generator

Generate random UUID v4 values or ULIDs, and check a pasted UUID or ULID. Everything happens in your browser.

Which kind of ID?

Whole numbers only, from 1 to 100.

Press Generate to make IDs.

    Check an ID

    Paste an ID to see its kind, version or creation time.
    IDs are generated in your browser with the browser's secure random source (crypto.getRandomValues). Nothing is sent anywhere, and nothing is stored. A ULID embeds its creation time in milliseconds, so anyone who sees a ULID can read when it was made. A UUID v4 carries no time.

    How it works

    UUID v4 takes 16 random bytes. Four bits are set to version 4 and two bits to the variant 10, then the 32 hex digits are written in the groups 8-4-4-4-12. The result is 36 characters with hyphens.

    ULID is 26 characters. The first 10 hold a 48-bit millisecond timestamp from the clock on your device, and the last 16 hold 80 random bits. Both parts use Crockford base32, which leaves out I, L, O and U so the IDs are easy to read and type. Because the time comes first, ULIDs sort in creation order.

    Check an ID accepts upper or lower case. A UUID shows its version from the version digit (1 to 8, or unknown). A ULID shows the time it was created, decoded from its first 10 characters.