UUID / GUID Generator
Generate random UUIDs (v4). Configurable count, format (with/without dashes), and casing.
About UUID / GUID Generator
UUID (Universally Unique Identifier, also called GUID on Microsoft platforms) is a 128-bit value formatted as 32 hex characters separated by hyphens into 8-4-4-4-12 groups. Version 4 UUIDs are entirely random — the namespace is so large that collisions are effectively impossible. This tool uses the browser's built-in crypto.randomUUID, which is cryptographically secure.
When to use it
- Generating primary keys for new database records
- Producing request/correlation IDs for tracing
- Creating filenames for uploads where collisions must be impossible
- Tagging anonymous users or sessions
How it works
Each UUID is produced by crypto.randomUUID(), which generates a v4 UUID using 122 bits of cryptographically secure randomness plus 6 fixed bits encoding the version and variant. Format options post-process the output to remove dashes, uppercase, or both.
Examples
Count=3, default format
550e8400-e29b-41d4-a716-446655440000 6ba7b810-9dad-11d1-80b4-00c04fd430c8 f47ac10b-58cc-4372-a567-0e02b2c3d479
Frequently asked questions
- Which UUID version is this?
- Version 4 (random). The other widely-used variants are v1 (time + MAC address) and v7 (time-sortable, draft) — neither is generated by this tool.
- What's the collision probability?
- v4 UUIDs have 122 bits of randomness, ~5.3 × 10³⁶ possible values. To have a 50% chance of any collision you'd need to generate ~2.7 × 10¹⁸ UUIDs. For practical purposes: impossible.
- Is this the same as GUID?
- Yes. GUID is Microsoft's name for UUID; the two formats are identical. Microsoft platforms sometimes wrap them in curly braces ({...}); this tool's output matches the standard RFC 4122 form without braces.