freesabaiUUID generator (v4 and v7)
Make UUIDs of version 4 (random) or 7 (time-ordered, good as database keys), many at once, written the way you need. Copy them all in one go, and paste a UUID you already have to read its version and the time inside it. They are made on your device with the browser's secure random numbers and are not sent anywhere.
This tool needs JavaScript. If you still see this after a few seconds, JavaScript is switched off in your browser or the page did not load completely: turn JavaScript on or reload the page.
How to use it
- Choose the version (v4 or v7) and how many. The UUIDs appear at once. Press "Make a new batch" for a fresh set.
- Choose how they are written: upper case, without hyphens, or in { } braces. Changing the style does not make new values.
- Press "Copy" for all of them (one per line), or "Download" a .txt file.
Frequently asked questions
What is the difference between UUID v4 and v7, and which should I use?
v4 is entirely random (122 bits) and is fine in general, but as a database primary key it scatters at random, which slows the index. v7 puts the time (in milliseconds) first, so a UUID made later is always greater: the database sorts and inserts faster. It suits primary keys if your database and libraries support it.
Could a UUID I make equal someone else's?
With v4 the chance is so small that it can be ignored: you would need about 2.7 quintillion UUIDs for even odds of one repeat. This page uses the browser's secure random numbers (crypto.getRandomValues), not Math.random, which can be predicted.
Are several v7 UUIDs made in the same millisecond in the right order?
Yes. The v7 of this page puts a 12-bit counter after the time, so UUIDs made in the same millisecond always sort in the order they were made. If the counter fills up, the time moves on by one millisecond and never goes back.
Good to know
- A UUID is not a secret. Do not use one as an authentication token even though a v4 is hard to guess: use a proper token generator.
- A v7 shows the time it was made. If you do not want anyone to learn when a record was made, use v4.
- The "Read a UUID" box reads UUIDs with or without hyphens, in { } and as
urn:uuid:, and tells the time of a v1 or v7.
Your data stays on your device
Everything runs in your browser. What you type, paste or open is not sent to freesabai's servers or anyone else's, and is not kept in the browser: close the page and it is gone. The site only counts how many times this page was opened and how many times someone copied or saved a result (never what was pasted or the result, and you can switch the counting off in the footer; see the privacy policy).
Report a problem or suggest an idea
Found a bug, or want this tool to do more? Tell us on the feedback page. No sign-up.
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