How do I generate a UUID (unique identifier)?
Generates UUIDv4 (purely random) and UUIDv7 (time-sortable, RFC 9562 from 2024).
Everything is randomized in your browser via Web Crypto API, never leaves.
Generate 1-50 IDs at a time, in your chosen format (with hyphens, plain, uppercase, braces for Microsoft GUID style).
Ideal for developers: database row IDs, event message IDs, request IDs in logs, idempotency keys, S3 object keys.
How to use it
- Pick a version: UUIDv4 for purely random, UUIDv7 for time-sortable.
- Slide the count knob to choose how many UUIDs at once (1-50).
- Pick a format: hyphens (RFC standard), plain (no hyphens), uppercase, or braces (Microsoft GUID style).
- Click any UUID = copies to clipboard. "Copy all", all at once, separated by newlines.
When this is useful
Seven typical situations where a UUID solves the uniqueness problem without coordination:
- Databases. Primary keys (especially MySQL BIN(16), Postgres UUID type); UUIDv7 shines here, time-sorted, so B-tree indexes don't fragment like v4 inserts do.
- Events / message brokers. Kafka message keys, RabbitMQ correlation IDs.
- Logs. Request IDs for distributed tracing across microservices.
- S3 / object storage. Object keys to avoid name collisions.
- Idempotency keys. HTTP "Idempotency-Key" header for payment APIs.
- JavaScript / Node. React component keys when you have no other stable ID.
- Day-to-day. Quick test IDs when you don't want to think about naming.
Questions and answers
UUIDv4 = 122 random bits, practically zero collision risk, but database inserts hop around the B-tree (each new row lands in a random spot). UUIDv7 = 48-bit Unix timestamp + 74 random bits, IDs are time-sortable, B-tree indexes are B+tree-friendly (sequential inserts). UUIDv7 has been the default for new projects since 2024.