UUID Generator Online β UUID v4, v7 and GUID
Generate UUID v4, v7 or GUID with one click. Bulk generation up to 1000, copy with a single button, download as .txt. Runs in your browser, nothing is sent to a server.
UUID v4 β 122 random bits + 6 service bits. The default in most libraries and databases.
About the UUID Generator
A UUID (Universally Unique Identifier) is a 128-bit identifier with a collision probability so low you can use it without any central authority. All values are generated in your browser via crypto.getRandomValues β no data is sent to a server.
UUID versions and where to use them
UUID v4 β random
122 random bits + 6 service bits. The most common version: API ids, keys, password reset links. Doesn't sort, can fragment a database index.
UUID v7 β time-ordered
48 bits of unix milliseconds + 74 random bits. Sorts lexicographically by creation time β perfect for primary keys in PostgreSQL or MySQL: less index fragmentation than v4.
GUID β Microsoft format
Same as UUID v4 but uppercase and wrapped in braces: {ABCDEF12-...}. Used in .NET, COM, the Windows Registry and most MS tooling.
FAQ
What's the difference between UUID v4 and v7?
v4 is fully random β simple and reliable, but bad for sorted database indexes. v7 puts a timestamp in the first 48 bits, so identifiers grow over time and behave like a clustered key β the new de-facto standard for primary keys.
What's the collision probability of UUID v4?
You'd need to generate around 2.7Γ10ΒΉβΈ values to have a 50% chance of even one collision. In practice, collisions don't happen.
Are UUID and GUID the same thing?
Technically yes β GUID is Microsoft's term for UUID. The only difference is formatting: GUIDs are usually uppercase and wrapped in braces, UUIDs are lowercase without braces.
Can I use UUID for short URLs or promo codes?
You can, but 36 characters is long. For short links use nanoid or shorten the UUID via base62. For promo codes use a dedicated generator with a confusion-free alphabet.
Is it safe to generate UUIDs on the client for authentication?
For random session ids and tokens β yes, we use the cryptographically secure crypto.getRandomValues. For secrets (API keys, refresh tokens) issue them on the server so the client can't influence the algorithm.
Are generated UUIDs stored on the server?
No. Every value is created in your browser and stored nowhere. Close the tab and the list is gone. Save important UUIDs yourself via "Download .txt" or copy them.