UUID / GUID Generator

Generate RFC 4122 v4 UUIDs — bulk generation and multiple formats

Your input never leaves your browser — all processing happens client-side.

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Format Preview

4e46ee18-1bf0-40ee-8f89-da96961bb09d

4e46ee18-1bf0-40ee-8f89-da96961bb09d

Generated using crypto.randomUUID() — cryptographically secure

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Free Online UUID / GUID Generator — RFC 4122 v4

UUID (Universally Unique Identifier) v4 generates random 128-bit identifiers with an astronomically low collision probability. This tool uses your browser's cryptographically secure random number generator to produce UUIDs in multiple formats: standard, no-dashes, uppercase, and GUID-style braces.

What is UUID / GUID Generator?

A UUID is a 128-bit label used for information in computer systems. Version 4 UUIDs are randomly generated, making them suitable as unique identifiers for database records, session tokens, file names, and API resources. The probability of generating a duplicate UUID v4 among 1 trillion UUIDs is approximately 1 in a billion — for practical purposes, collisions are impossible.

How to Use This Tool

  1. 1Click 'Generate' to produce a single UUID.
  2. 2Adjust the count slider to generate up to 100 UUIDs at once.
  3. 3Select your preferred format: standard, no dashes, uppercase, or GUID braces.
  4. 4Click the copy icon next to any UUID, or 'Copy All' to copy the full list.
  5. 5Click 'Regenerate' to produce a fresh batch.

Use Cases

  • ▸Database primary keys — unique record identifiers in PostgreSQL, MySQL, MongoDB.
  • ▸Session tokens and request IDs for web applications.
  • ▸File naming — unique names for uploaded files to prevent collisions.
  • ▸Testing and development — generating test data with unique identifiers.
  • ▸Distributed systems — generating IDs without a central coordinator.

Is It Safe to Use?

UUIDs are generated using crypto.randomUUID() where available, or the Web Crypto API (crypto.getRandomValues) as a fallback. Both are cryptographically secure random number generators built into every modern browser. No data is sent anywhere.

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Frequently Asked Questions

What is a UUID?

A UUID (Universally Unique Identifier) is a 128-bit identifier standardized by RFC 4122. It is typically expressed as 32 hex digits separated by hyphens in the format 8-4-4-4-12. The chance of two randomly generated UUID v4s colliding is astronomically small.

What is the difference between UUID and GUID?

A GUID (Globally Unique Identifier) is Microsoft's implementation of UUID. They are functionally identical — both are 128-bit identifiers following the same RFC 4122 standard. The term GUID is common in .NET and Windows environments.

Is UUID v4 truly random?

UUID v4 uses random or pseudo-random numbers for all bits except the version (4) and variant bits. This tool uses crypto.randomUUID() or the Web Crypto API, which provides cryptographically secure random numbers.

Can I use these UUIDs in a database?

Yes. UUID v4 is widely used as primary keys in databases (PostgreSQL, MySQL, MongoDB, etc.). Be aware that random UUIDs can cause index fragmentation in clustered indexes — some databases offer UUID v7 (time-ordered) for better performance.

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