UUID Generator
Generate random version 4 UUIDs (also called GUIDs), one at a time or thousands at once — free and instant. Every ID is built from your browser's cryptographically secure random generator and never touches a server.
How to use the UUID Generator
- Grab a single UUID. One is generated the moment the page loads. Press New UUID for a fresh one and copy it with the button.
- Choose your format. Toggle uppercase, remove the dashes, or wrap each ID in braces for a classic Microsoft GUID look. Options apply to both the single value and the bulk list.
- Generate in bulk. Enter how many you need, press Generate list, then copy them all or download them as a text file.
About this tool
A UUID (Universally Unique Identifier), known on Windows platforms as a GUID, is a 128-bit value written as 32 hexadecimal digits in the pattern 8-4-4-4-12. This generator produces version 4 UUIDs, which are almost entirely random: 122 of the 128 bits come straight from randomness, with the remaining bits fixed to mark the version and variant. That gives roughly 5.3 × 10³⁶ possible values, so the odds of ever generating the same one twice are negligible — which is exactly why UUIDs are used as database primary keys, request and trace IDs, file names, session tokens and idempotency keys in distributed systems where separate machines must create unique IDs without coordinating.
Randomness quality matters for uniqueness, so this tool draws its bytes from crypto.getRandomValues, the browser's cryptographically secure random number generator, rather than the weaker Math.random. Bits 13 and 17 are set to declare version 4 and the RFC 4122 variant, exactly as the specification requires. Everything is generated locally in your browser, so no identifier is ever sent to or logged by a server — you can safely create keys for private or production systems. Need many at once? The bulk generator can produce up to 10,000 IDs in a single click.
Frequently asked questions
Are these UUIDs truly unique?
Version 4 UUIDs are not guaranteed unique but are effectively so in practice. With 122 random bits, you would need to generate about a billion UUIDs per second for around 85 years to reach a 50% chance of a single collision, so they are safe to use as identifiers without a central authority.
What is the difference between a UUID and a GUID?
They are the same thing. GUID (Globally Unique Identifier) is Microsoft's name for the identifier defined by the UUID standard. GUIDs are often shown in uppercase and wrapped in braces, like {2FA85F64-...} — enable those options above to match that style.
Is the randomness secure enough for tokens?
The bytes come from crypto.getRandomValues, a cryptographically secure source, so version 4 UUIDs are suitable as unpredictable identifiers. For high-security secrets like password-reset tokens, many teams still prefer a dedicated random token, but a v4 UUID is a solid, unguessable choice.
Do you store or see the UUIDs I generate?
No. Generation happens entirely in your browser with local JavaScript — nothing is transmitted, logged or stored. Reload the page and every value is gone, which makes it safe for production keys and confidential systems.