UUID Generator
Generate version 4 UUIDs with your browser's secure random number generator. Bulk generate, copy, download, and format as GUIDs. Nothing is uploaded.
Your UUIDs appear here.
Processed locally in your browser. Your data never leaves your device.
About this UUID generator
A UUID (universally unique identifier) is a 128-bit value used to label records, files, sessions and events without any central coordination. This tool generates version 4 UUIDs, which are made of random bits, using your browser's secure random number generator. Generate one or up to 1,000 at a time, format them, then copy them individually or all at once, or download them as a text file.
How to use it
- Enter how many UUIDs you want (1 to 1,000) and choose Generate. One is already created when the page loads.
- Optionally switch to uppercase, remove the hyphens, or add braces. Formatting changes only how the same values are written.
- Copy a single UUID, copy them all (one per line), or download the list.
Example
A version 4 UUID looks like 3f2b8c1e-9a47-4d6b-8e15-2c7a90b4d1f3. The 4 starting the third group marks the version, and the 8 starting the fourth group is the variant (RFC 4122). Formatted as a GUID it becomes {3F2B8C1E-9A47-4D6B-8E15-2C7A90B4D1F3}.
Choosing an identifier
- Random UUIDs (v4) are ideal when identifiers must be created independently, on many machines, without coordination.
- Database keys. Random keys scatter inserts across an index, which can hurt write performance on very large tables. Time-ordered identifiers (such as UUID v7, ULID or sequential IDs) keep new rows together.
- Do not use them as secrets. Use a dedicated generator for API keys and passwords.
- Case and hyphens are cosmetic.
ABC…andabc…are the same UUID. Compare them case-insensitively.
Frequently asked questions
- Are these UUIDs really random and unique?
- They come from your browser's cryptographically secure random number generator (Web Crypto), never from Math.random. A version 4 UUID has 122 random bits, so the chance of two ever colliding is negligible: you would need to generate about a billion UUIDs per second for roughly 85 years to reach a 50% chance of a single duplicate.
- Can I use a UUID as a password, API key or secret token?
- A UUID is an identifier, not a secret. Version 4 UUIDs are unpredictable, but the format is well known and many systems log or expose them. Use a purpose-built secret generator for keys and tokens.
- What is the difference between a UUID and a GUID?
- GUID is the name Microsoft uses for the same 128-bit identifier. It is often written in uppercase, sometimes with braces: {123E4567-E89B-42D3-A456-426614174000}. Use the format options to match.
- Why are the version digit and variant fixed?
- In 123e4567-e89b-42d3-a456-426614174000 the first digit of the third group (4) is the version and the first digit of the fourth group (8, 9, a or b) is the variant. That leaves 122 random bits, which is why every v4 UUID looks like xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx.
- Are the generated UUIDs sent to a server?
- No. They are generated in your browser and never leave your device. Nothing is uploaded, stored or logged.