UUID generator
Generate v4 and v7 UUIDs in bulk.
FreeRuns in your browserNo signupUpdated 2026-10-29
Generated with the Web Crypto API in your browser. Nothing is stored or sent anywhere.
Generated
0
UUID v4
Characters
36
Per id, as formatted
Random bits
122
Collisions are not a practical concern
About this tool
How it works and how to read the result.
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Web app & SaaS development
SaaS products and web apps, from first version to scale.
See the serviceWhat it does
The UUID generator produces version 4 and version 7 identifiers in bulk, up to 100 at a time, one per line for pasting into a seed script, a test fixture or a spreadsheet. Version 4 is fully random. Version 7 starts with a 48-bit millisecond timestamp, so ids created later sort after ids created earlier, which is why newer databases and the RFC 9562 standard recommend it for primary keys. Options give you uppercase hex or the 32-character form without hyphens. A small panel breaks down the first id so you can see the version digit and the embedded time.
How to use it
- Choose v4 for random ids or v7 for time-ordered ids.
- Set how many you need with the slider, from 1 to 100.
- Tick uppercase or remove hyphens if the database, API or file you are pasting into expects that format.
- Click "Generate again" for a fresh batch, then copy the list or download it as a text file.
How to read the result
A v4 id such as 8d3453ed-7111-4fcb-83c9-4247866ad1a3 has a 4 as the 13th hex digit and one of 8, 9, a or b as the 17th. Those two positions are fixed by the standard; the other 122 bits are random.
A v7 id such as 01a185d1-0f19-75f6-af08-fc0a52777744 carries its creation time in the first 12 hex digits: 01a185d10f19 is a millisecond count since 1970, which the anatomy panel converts to a date. The 7 in position 13 is the version. Generate five v7 ids and they are in ascending order; the generator nudges each by one millisecond so they sort cleanly even within the same batch.
Characters per id is 36 with hyphens and 32 without. Most databases store either in 16 bytes with a native UUID type; storing them as text takes 36 bytes and sorts more slowly.
We use v7 keys by default in web app development. For random secrets rather than identifiers, use the password generator.
Questions
Frequently asked.
Should I use v4 or v7?
Use v7 for database primary keys and anything you will sort or page through, because new ids sort after old ones and keep indexes compact. Use v4 where order would leak information, such as public tokens or invitation links, or where the receiving system expects v4.
Can two generated UUIDs collide?
With 122 random bits in v4, you would need to generate about a billion ids per second for decades before a duplicate became likely. v7 has 74 random bits per millisecond, which is still far beyond anything one system produces. Treat them as unique.
Are these generated securely?
Yes. Both versions use crypto.getRandomValues, the browser's cryptographic random source, and v4 uses crypto.randomUUID where available. Nothing is generated on a server or stored, so the ids exist only on your screen until you copy them.
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