Security / Data tool
UUID Generator
Generate random UUID v4 values with the browser Web Crypto API. Create one or many at once.
Result
Your result will appear here.
How to use UUID Generator
- Choose the number of UUIDs to generate.
- Select Generate, then copy or download the values.
Example
Generate a UUID v4Common use cases
- Creating primary keys or correlation IDs for a test database or a fixture file where the IDs must not collide.
- Generating a unique request ID to attach to a log line while you reproduce a bug.
- Producing a batch of IDs for a spreadsheet or import file by setting the number of UUIDs and copying the result.
Input and output examples
| Input | Output | Notes |
|---|---|---|
3 | 3 values, each shaped like xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx | The x digits are random. The 4 marks version 4, and y is 8, 9, a, or b. |
101 | Choose a number between 1 and 100. | The generator rejects counts outside the allowed range. |
Common mistakes to avoid
- Pick the right version. This tool makes version 4 only. Random v4 values are not sortable by creation time, so use UUID v7 from RFC 9562 when you need time-ordered keys.
- Hexadecimal letters are case-insensitive under RFC 4122, but some systems store uppercase. Normalize the case before comparing values from different systems.
- Keep the hyphens. A UUID written without hyphens is the same 32-digit value, but a validation rule that expects 36 characters will reject it.
Technical details
UUIDs follow RFC 4122 (and its successor RFC 9562): 128-bit values written as 32 hexadecimal digits in five groups. A version 4 UUID has the digit 4 at the start of the third group, and the first digit of the fourth group is 8, 9, a, or b. The tool uses crypto.randomUUID when the browser provides it. Otherwise it fills 16 bytes from crypto.getRandomValues and sets the version and variant bits itself.
Frequently asked questions
Are UUIDs generated on a server?
No. UUID values are generated in your browser using cryptographic randomness.
Can two generated UUIDs be the same?
The tool does not check against earlier values, but a version 4 UUID has 122 random bits, so an accidental repeat is extremely unlikely.
What is the difference between UUID v1 and v4?
v1 combines a timestamp with a node identifier, which was historically a MAC address, so it can reveal when and where it was created. v4 is random and reveals neither.
Why is the limit 100 UUIDs at a time?
The field and the generator both accept 1 to 100 values per run. Enter a number outside that range and the tool shows an error.
Can I use a UUID as a password or API key?
RFC 4122 defines UUIDs as identifiers, not secrets. For passwords or API keys, generate a longer random string with a tool designed for secrets and store it securely.
What is UUID v7?
RFC 9562 defines v7, which starts with a Unix millisecond timestamp so IDs sort by creation time. This tool generates only version 4.