~/devtools / uuid
tool::uuid

UUID
Generator

Generate RFC 4122 compliant UUID v4 identifiers. Generate up to 20 at once with individual or bulk copy.

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// about UUID v4
UUID v4 uses random numbers. Format: 8-4-4-4-12 hex digits. Example: 550e8400-e29b-41d4-a716-446655440000
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// about this tool

What is a UUID?

A UUID (Universally Unique Identifier) is a 128-bit identifier that is globally unique. Following the RFC 4122 standard, it is represented as 32 hexadecimal characters in the format 8-4-4-4-12. UUIDs can be generated without a central server and without fear of collisions.

UUID v4 is the most widely used version, filling 122 of the 128 bits with cryptographically secure random numbers. The probability of generating the same UUID twice is less than one in a trillion — practically impossible in real-world use.

This tool generates RFC 4122 UUID v4 values using the browser's built-in crypto.randomUUID() API. You can generate up to 20 at once and copy them individually or all at once.

Use Cases
  • ▸Generate primary keys for database tables
  • ▸Assign collision-free filenames to uploaded files
  • ▸Create entity identifiers across distributed systems without central coordination
  • ▸Generate correlation IDs for API request tracing
  • ▸Create session IDs or temporary tokens
FAQ
Q. How does UUID v4 differ from v1, v5, etc.?
v1 is based on MAC address and time, v3/v5 are based on namespace and name hashes, and v4 is purely random. v4 is the most commonly used and poses no privacy concerns.
Q. Are UUIDs truly unique?
Collisions are theoretically possible but astronomically unlikely. Even generating a billion UUIDs per second for 100 years would give less than a 50% chance of a collision. For all practical purposes, they are unique.
Q. What should I watch out for when using UUID as a database key?
Because UUID v4 is fully random, it causes frequent B-Tree index page splits, which can degrade insert performance. For high-traffic workloads, consider sortable alternatives like ULID or UUID v7.
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