About this tool
What is a UUID?
A Universally Unique Identifier is a 128-bit label written as 32 hexadecimal digits in five groups (8-4-4-4-12), for example 550e8400-e29b-41d4-a716-446655440000. Versions differ in how the bits are chosen: v1 embeds time and MAC, v4 is fully random, v7 adds a sortable timestamp, nil is all zeros.
How to use it
- Pick a version (v4 is the safe default for most IDs) and a quantity.
- Copy one value or export the whole batch as plain text or JSON.
- Use ULIDs instead when you need lexicographically sortable IDs.
Examples
- Primary keys for database rows created across distributed services.
- Idempotency keys so retried API requests do not double-apply.
- Correlation IDs tracing one request through many microservices.
Important limitations
- UUIDs are unique, not secret: v1 leaks MAC address and timestamp, so never use UUIDs as passwords or tokens.
- Random v4 UUIDs are not sortable and fragment database indexes; v7 fixes ordering.
- Collisions are astronomically unlikely but not mathematically impossible.
Privacy
Values are generated with the Web Crypto API on your device. Nothing is sent anywhere, and generated IDs are not recorded.
Frequently asked questions
v1, v4 or v7?
v4 for general random IDs. v7 when rows must sort by creation time. v1 only when you specifically need time-based legacy behavior.
Can I use a UUID as a password?
No. Use the password generator or a token generator — UUIDs lack the entropy policy and rotation story secrets need.
Uppercase or lowercase?
RFC allows both; lowercase without braces is the common interchange form this tool emits.
Related tools
ULID generator · Token generator · Password strength checker