UUID v4 Generator
Generate random UUID version 4 identifiers instantly. Client-side only — nothing leaves your browser.
Random, 128-bit, RFC 4122. Most widely used.
When to use which type▼
UUID v4
Purely random (RFC 4122). The most widely supported unique identifier format. Use when you need a standard UUID and sorting by creation time does not matter.
UUID v7
Time-ordered UUID (RFC 9562). The first 48 bits encode a millisecond timestamp, making IDs lexicographically sortable. Prefer over v4 for database primary keys — better index locality, fewer B-tree page splits.
ULID
26-character Crockford Base32 string: 10 chars timestamp + 16 chars randomness. Lexicographically sortable and URL-safe. A compact drop-in for UUID when a shorter, human-readable identifier is preferred.
NanoID
Configurable length and alphabet. Best for short tokens, session IDs, and slugs. The default 21-character length has the same collision probability as UUID v4.
Common Use Cases
- Database primary keysGenerate UUID v4 values to use as primary keys in PostgreSQL, MySQL, or MongoDB. Works with any database that supports UUID or VARCHAR(36) columns.
- API correlation IDsAttach a UUID v4 to each API request as a correlation ID for distributed tracing and log correlation across microservices.
- Idempotency keysGenerate a UUID v4 to use as an idempotency key when calling payment APIs (Stripe, Adyen) to safely retry requests without double-charging.
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