UUID v7 Generator (Time-Ordered) & Decoder

UUID version 7 is the newest standard UUID, defined in RFC 9562 (2024), and it solves the biggest practical problem with the classic random UUID v4: ordering. A v4 UUID is 122 bits of pure randomness, so consecutive values land in unrelated positions. Used as database primary keys, every insert scatters across the B-tree index, which fragments pages, hurts cache locality, and slows writes at scale.

UUID v7 fixes this by putting a 48-bit Unix millisecond timestamp at the front of the identifier, followed by the version and variant bits and 74 bits of randomness. Because the timestamp leads, v7 values are time-ordered: sort them as strings and they come out in creation order. New rows append near the end of the index instead of scattering, so you keep the insert performance of an auto-incrementing integer while keeping the decentralization and unguessability of a UUID — with no central allocator.

A v7 UUID looks identical in shape to any other UUID (32 hex digits in the 8-4-4-4-12 layout), with the version digit fixed to 7. Because the timestamp sits in plain view, you can also decode roughly when an ID was created, which is handy for debugging or auditing without a separate created_at column. This tool generates cryptographically random v7 UUIDs with your browser crypto API, and the decoder reads the timestamp back out of any v7 you paste.

Everything runs locally — no value is ever sent to a server, so the IDs are safe even in security-sensitive contexts. If you want maximum write performance on a UUID primary key, v7 is usually a better default than v4; if you specifically need IDs with no time signal at all, stay with v4.