UUID v7 generator
Creates version 7 UUIDs from RFC 9562, which sort by creation time and so work well as database primary keys.
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Processing and privacy: The result is calculated inside your browser and your data is not sent to any server.
How to use it
- Enter how many, unix time in ms (leave empty for now) and uppercase.
- The result appears straight away and updates as you edit.
- Copy the result, or copy a link that keeps the same values to share it.
How it is calculated
The first 48 bits are the Unix time in milliseconds, then version bits 0111, 12 random bits, variant bits 10 and 62 random bits. Within a batch and the same millisecond the random part is incremented by 1 to keep order.
Example
Inputs: How many = 5, Uppercase = no. Result: UUIDs: 01a1939c-1e84-7120-b907-e6c0b383498f 01a1939c-1e84-7120-b907-e6c0b3834990 01a1939c-1e84-7120-b907-e6c0b3834991 01a1939c-1e84-7120-b907-e6c0b3834992 01a1939c-1e84-7120-b907-e6c0b3834993; Time of first id (UTC): 2026-10-31T20:17:24.612Z; Count: 5.
Limits and caveats
- Anyone who sees the id can read when it was created, so avoid it where timing must stay private.
- Accuracy depends on your device clock; a wrong clock gives a wrong timestamp.
Questions about this tool
Why do developers prefer UUID v7 over v4 in databases?
New ids sort after old ones, so they land at the end of a B-tree index instead of random positions, which reduces index fragmentation.
How do I read the time from a UUID v7?
The first 12 hex characters, ignoring the hyphen, are the Unix time in milliseconds. You can also paste the id into the UUID validator to read its date.
Is it still unique when several ids share a millisecond?
Yes, 74 bits stay random, and within one batch the random part is incremented by 1 so values never repeat.