UUID Generator
Generate one or thousands of UUIDs (v1, v4 and v7) in bulk, ready to copy or download, with v4 using your browser's secure randomness. Free and instant.
UUIDs in v1, v4 and v7, up to 100 at a time
Choose a version, set a quantity from 1 to 100 and generate. Each UUID has its own copy button, and copy all puts the whole batch on the clipboard one per line, which drops straight into a SQL insert, a fixtures file or a spreadsheet column.
Version 4 is the right default for almost everything. It is 122 bits of randomness drawn from crypto.randomUUID(), the browser's cryptographically secure generator, so collisions are not a practical concern. Version 7 puts a millisecond Unix timestamp in the first 48 bits and random data after it, so values sort by creation time; that keeps database indexes compact when the UUID is a primary key. Version 1 is the older time-based layout; the node and clock-sequence fields here are random rather than taken from a MAC address, which is better for privacy but means it is not strictly RFC 4122 compliant.
The random portions of v1 and v7 come from Math.random rather than the crypto source, so use v4 where unguessability matters, such as tokens or reset links. Generation happens on the page with nothing sent or stored; reloading produces a completely new set.
Frequently asked questions
What is the difference between a UUID and a GUID?
Nothing in practice. GUID is Microsoft's name for the same 128-bit identifier format; the text form is identical.
Can two generated UUIDs collide?
A v4 UUID has 122 random bits, so the chance of a duplicate is negligible even across billions of values. v1 and v7 include a timestamp, which makes duplicates within the same millisecond less unlikely but still rare.
Which version should I use for a database primary key?
v7. Its leading timestamp means new rows land near each other in the index, which avoids the page splits and cache misses that random v4 keys cause at scale.
Is a UUID safe to use as a secret token?
A v4 UUID from this page has 122 bits of cryptographic randomness, which is adequate, but v1 and v7 reveal when they were created and use weaker randomness, so do not use those for anything secret.