Free tools
UUID Generator
Generate random UUIDs (v4) instantly in your browser — free, no sign-up, nothing sent to a server.
Generated UUIDs
UUID Generator Online
Generate one or more random version 4 UUIDs instantly. Choose how many you need, click Generate UUID, and copy the results. Everything runs in your browser using the Web Crypto API — nothing is sent to a server.
What Is a UUID?
A UUID (Universally Unique Identifier) is a 128-bit label used to uniquely identify information in computer systems. Version 4 UUIDs are randomly generated and have the form xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx where x is a random hex digit. The probability of generating a duplicate UUID is astronomically small.
Common Uses
- Primary keys for database records
- Unique identifiers for distributed systems where a central counter is impractical
- Correlation IDs for tracing requests across microservices
- Filenames for uploaded files to avoid collisions
- Session or token identifiers
Frequently Asked Questions
What is a UUID?
UUID stands for Universally Unique Identifier. It's a 128-bit number used to uniquely identify information in computer systems. UUIDs are designed to be unique across both space and time, making them ideal for database keys, session IDs, and distributed systems.
What version of UUID does this tool generate?
This tool generates UUID v4 (version 4), which is the most commonly used type. Version 4 UUIDs are randomly generated and have 122 bits of randomness, making the chance of collision astronomically low.
What format does a UUID use?
UUIDs follow a standard format of 8-4-4-4-12 hexadecimal digits, like
550e8400-e29b-41d4-a716-446655440000. The hyphens are part of the standard format but can be removed if needed.When should I use UUIDs?
Use UUIDs when you need unique identifiers that don't require a central authority to generate. Common use cases include: database primary keys, API request IDs, session tokens, file names, distributed system identifiers, and anywhere you need guaranteed uniqueness without coordination.
Are UUIDs truly unique?
UUID v4 has 122 bits of randomness, meaning there are approximately 5.3 × 10³⁶ possible values. While technically not impossible, the probability of generating the same UUID twice is so incredibly small that for practical purposes, they can be treated as unique. You'd need to generate billions of UUIDs per second for centuries to have a reasonable chance of collision.
Is this tool secure?
Yes. UUID generation happens entirely in your browser using JavaScript's cryptographically secure random number generator. No data is sent to any server, and generated UUIDs are never stored or logged.