What is UUID Generator?
UUID Generator creates cryptographically random UUID v4 identifiers — one at a time or in bulk. Use them as primary keys, test data, idempotency keys, correlation IDs, or anywhere a globally unique identifier is needed.
UUID v4 is the safe default for most use cases. It’s random, carries no information about when or where it was generated, and is accepted by every database and language ecosystem.
UUID Versions Compared
UUID v1 (Time-based)
Encodes the current time + MAC address. Ordered, but leaks machine identity. Avoid in public APIs.
UUID v4 (Random)
122 random bits. No information leaked. The most common choice for application IDs.
UUID v5 (Name-based)
Deterministic — same name + namespace always produces the same UUID. Useful for deduplication.
UUID v7 (Sortable)
Combines timestamp prefix with random bits. Sortable like auto-increment but still globally unique.
How to Use UUID Generator
Choose quantity
Set how many UUIDs to generate — 1 for a quick one-off, up to 100 for bulk test data seeding.
Choose format
Standard (with dashes), no-dashes, or uppercase — whatever your system expects.
Generate
Click Generate and the list appears instantly. All generated client-side, no network request.
Copy one or all
Click any UUID to copy it, or 'Copy all' to get the whole batch newline-separated.
Common UUID Use Cases
| Use Case | Details |
|---|---|
| Database primary key | Replace auto-increment for distributed inserts |
| API idempotency key | Deduplicate retried requests |
| File / asset naming | {uuid}.jpg avoids filename collisions |
| Test data seeding | Generate many unique IDs for fixtures |
| Correlation ID | Trace a request across microservices |
| Session token | Use alongside a proper auth library |
Tips & Common Mistakes
Store as BINARY(16) not VARCHAR(36) in MySQL. The dashed UUID string is 36 characters. Storing as binary is 2.25× smaller and much faster for indexed lookups on large tables.
Don’t use UUID as a surrogate key in PostgreSQL without care. UUID v4 is random, so inserts scatter across B-tree index pages causing fragmentation. Use UUID v7 or gen_random_uuid() with fillfactor tuning, or use ULID for sortable random IDs.
Always include dashes for readability. The dashed format xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx is the official RFC 4122 representation and is accepted everywhere.
Related Tools
- JWT Generator — generate signed tokens that embed a UUID as a sub claim
- MD5 Generator — hash a UUID to create a deterministic short identifier
- Random Decision Maker — if you just need a random choice, not an ID