UUID Generator
Generate version 4 UUIDs using your browser cryptographic random source — one, or a thousand at a time.
Your data stays on your device
Generated with the Web Crypto API, not Math.random.
About this tool
A version 4 UUID is 122 random bits formatted as 36 characters. It lets independent systems mint identifiers without coordinating, which is why it appears everywhere from database primary keys to trace ids and idempotency keys.
Randomness quality matters. These UUIDs come from the Web Crypto API, the same cryptographically secure source used for key material, rather than from Math.random which is not suitable for identifiers that must not collide or be guessable.
How to use this tool
- Choose how many UUIDs you need.
- Pick a format: lowercase, uppercase, without hyphens, or brace-wrapped.
- Press Generate.
- Copy the list or download it as a text file.
Key features
- Cryptographically secure randomness from the Web Crypto API
- Bulk generation up to one thousand identifiers
- Lowercase, uppercase, hyphen-free and braced formats
- Optional quoting and comma separation for pasting into code
- Copy all and download as .txt
- Regenerate without reloading the page
Example
Input — Options
count: 3, format: lowercaseOutput — UUID
9f1c5a2e-3b7d-4e18-9c40-6a2f8d1b7e53
2d84b6c1-7f05-4a93-8e21-c5b9d0473a68
c710e935-84af-4d62-b0f7-19e3a8c245dbGood to know
- Only version 4 is generated. Time-ordered versions such as v7 are not available here.
- Random UUIDs make poor clustered primary keys in some databases because they defeat index locality.
- A UUID is an identifier, not a secret. Do not use one as an authentication token.
Frequently asked questions
Can two UUIDs collide?
In theory yes, in practice no. With 122 random bits you would need to generate billions per second for decades before a collision became likely.
Why not use Math.random?
It is not cryptographically secure and its output can be predictable. For identifiers this matters, so the Web Crypto API is used instead.
What is the 4 in a v4 UUID?
The version nibble, always visible as the first character of the third group. It marks the UUID as randomly generated rather than time or name based.
Should I strip the hyphens?
Only if your storage layer requires it. The hyphenated form is the canonical representation and is what most systems expect.
Your data stays on your device
Your data is processed locally in your browser and is not uploaded to our server. This page keeps working after you go offline, because there is nothing to send.