UUID Generator
Generate secure, unique identifiers (v1, v4, v5, ULID, NanoID) with custom formatting.
tune Configuration
layers Bulk Generator
verified_user Validator
FAQ
What is a UUID?
Is generation secure?
Can two UUIDs be the same?
What is the difference between v4 and v5?
Unique IDs Without a Central Authority
UUID versions, briefly
All UUIDs look alike — 36 characters, five dash-separated groups — but the version digit changes what's inside:
| Version | Built from | Use when |
|---|---|---|
| v4 (this tool) | 122 random bits | The default — almost every modern use |
| v1 | Timestamp + machine identifier | Need rough time-ordering; leaks MAC/time |
| v5 / v3 | Hash of a name + namespace | Same input must always yield the same ID |
| v7 (newer) | Timestamp + randomness | Database keys that sort by creation time |
Can two v4 UUIDs collide?
Theoretically yes, practically no: 122 random bits give 5.3 × 10³⁶ possibilities. Generating a billion UUIDs per second for a century leaves collision odds far below one in a billion. That's why distributed systems mint IDs locally without coordinating — two services, two phones, two offline apps can all generate keys simultaneously and never clash. The one rule: use a cryptographic random source, which this tool does via your browser's crypto API.
Where UUIDs fit (and where they don't)
Good: database primary keys that survive merging datasets, order/transaction references that don't reveal volume (sequential invoice #00042 tells competitors plenty), file names that never collide, idempotency keys for payment APIs. Less good: anything humans must read aloud or type — and they're identifiers, not secrets. For secrets, generate a proper password or an API token; for content-derived fingerprints, use a SHA-256 hash; for compact transport of binary data, that's Base64.