UUID Generator
Generate cryptographically random UUID v4 strings in bulk. Uses the browser's native crypto.randomUUID() API — the strongest source of randomness available. No data is sent to a server.
UUID Format
A UUID looks like: 550e8400-e29b-41d4-a716-446655440000
It is divided into five groups: 8-4-4-4-12 hexadecimal characters. For UUID v4, the third group starts with 4 and the fourth group starts with 8, 9, a or b.
When to Use UUIDs
- Database primary keys — avoids sequential IDs that expose record counts.
- Distributed systems — generates unique IDs across multiple servers without coordination.
- File names — avoids naming collisions in shared storage.
- Session tokens — unique identifiers for browser sessions or API keys.
UUID v4 vs Sequential IDs
| UUID v4 | Auto-increment integer | |
|---|---|---|
| Uniqueness | Globally unique | Unique per table |
| Predictability | Random — unpredictable | Sequential — predictable |
| Index performance | Slower (random inserts) | Faster (sequential) |
| Distributed use | Safe across servers | Requires coordination |
Frequently Asked Questions
What is a UUID?
A 128-bit identifier formatted as 32 hex digits in five hyphen-separated groups: xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx.
UUID v4 vs other versions?
v1 is time-based (includes MAC address), v4 is fully random (most common), v5 is name-based and deterministic.
Are UUIDs truly unique?
UUID v4 has 122 bits of randomness. Collision probability is ~1 in 5.3 undecillion — unique for all practical purposes.
Is UUID the same as GUID?
Yes. GUID is Microsoft's term for the same standard — identical format and structure.