UUID Generator
Generate UUIDs — universally unique identifiers — one at a time or in bulk. Choose random v4 for general use, or time-ordered v7 when you want IDs that sort by when they were made. Everything is generated in your browser.
Adjust the options to generate a result.
Generated in your browser with the device’s secure random generator (Web Crypto). Nothing you generate is sent to a server, saved, or put in the page address — copy it somewhere safe.
What a UUID looks like
A UUID is a 128-bit number written as 32 hexadecimal digits in five groups: 8-4-4-4-12. For example:
5fc38e63-977e-4ccc-bf20-21386e3188ca
Two of those digits are fixed markers — one shows the version, one shows the variant — and the rest carry the identifier itself.
v4 vs v7
- v4 (random) — 122 random bits. There's no pattern and no order; it's the everyday choice when you just need a unique value.
- v7 (time-ordered) — the first 48 bits are a Unix millisecond timestamp, followed by 74 random bits. Because the timestamp leads, v7 IDs generated later sort after earlier ones. That ordering makes them friendlier as database keys: rows insert in order, which keeps indexes tidy and inserts fast.
Both are valid UUIDs and both are unique in practice. Pick v4 unless you specifically want the time ordering v7 gives.
How unlikely is a collision?
Very. A v4 UUID has 122 random bits — about 5.3 undecillion (5.3 × 10³⁶) possible values. You would need to generate roughly 103 trillion UUIDs before the odds of hitting even one duplicate reached one in a billion. For any real system, "unique" is a safe assumption.
Generating in bulk
Need a batch? Set the count and the generator produces that many at once, ready to copy together. Every value is created on your device with the browser's secure random generator — nothing is sent to a server, so the IDs are yours the moment they appear.
Frequently asked questions
What is a UUID?
A UUID (universally unique identifier), also called a GUID, is a 128-bit value written as 32 hex digits in the pattern 8-4-4-4-12, like 5fc38e63-977e-4ccc-bf20-21386e3188ca. It's used as an ID for database rows, files, sessions, and anything that needs a name guaranteed not to clash with another — without a central authority handing them out.
What's the difference between UUID v4 and v7?
v4 is fully random: 122 of its bits are random, so it has no built-in order. v7 puts a millisecond timestamp in the first 48 bits followed by 74 random bits, so v7 IDs sort in the order they were created. Use v4 as the default; use v7 when time-ordering helps, such as database primary keys where ordered inserts are faster.
Can two UUIDs ever be the same?
In practice, no. A v4 UUID has 122 random bits, so collisions are astronomically unlikely — you'd need to generate around 103 trillion of them before the chance of a single duplicate reached one in a billion. For any normal application you can treat them as unique.