A UUID (Universally Unique Identifier) is a 128-bit label used to uniquely identify objects in computer systems. It is standardized by RFC 4122 and written as a 32-character hexadecimal string split into five groups by hyphens: xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx.

What is a UUID version 4?

Version 4 UUIDs are randomly generated. 122 of the 128 bits are random (the remaining 6 encode the version and variant). This makes them suitable for any context where you need a unique ID without a central coordinator. The collision probability for 1 billion UUIDs is roughly 1 in a billion.

Are the generated UUIDs truly unique?

With 122 random bits, the probability of two version 4 UUIDs colliding is astronomically small (approximately 1 in 5.3 × 10^36). For all practical purposes, they are unique. This tool uses crypto.randomUUID() when available, falling back to crypto.getRandomValues() for full cryptographic-quality randomness.

What is a UUID without hyphens used for?

Some systems (databases, URLs, or API keys) require a compact 32-character hex string without hyphens. Disable 'Include hyphens' to produce the compact format: e.g. 550e8400e29b41d4a716446655440000.

Can I generate UUIDs for database primary keys?

Yes. UUID v4 is one of the most common primary key types for distributed systems because it can be generated client-side or server-side independently without risking collisions. Copy or download the list and insert it directly into your seed scripts.

ToolsUUID / GUID Generator

UUID / GUID Generator

Generate RFC 4122 version 4 UUIDs and GUIDs in bulk. Customize case, braces, and hyphens. Runs entirely in your browser.

Options

How many UUIDs?

UppercaseWrap in braces Include hyphens

Generated UUIDsEmpty

Generated UUIDs will appear here...

How to use UUID / GUID Generator?

1
Choose how many UUIDs to generate (1-1000).
2
Toggle uppercase, braces ({}), or hyphens to match GUID or compact formats.
3
Click Regenerate to produce a fresh batch.
4
Copy or download the generated list.

Frequently Asked Questions

What is a UUID?

A UUID (Universally Unique Identifier) is a 128-bit value used to uniquely identify information in computer systems. Version 4 UUIDs are randomly generated, making collisions astronomically unlikely.

What is the difference between UUID and GUID?

GUID (Globally Unique Identifier) is Microsoft's name for the same concept. They follow the same RFC 4122 standard. GUIDs are often written in uppercase and wrapped in braces, e.g. {AB12...}.

Are these UUIDs truly unique?

Version 4 UUIDs use 122 random bits. The probability of generating a duplicate is so small it is considered negligible for practically all applications.

Generate UUIDs and GUIDs Online

Quick Answer: A UUID is a 128-bit identifier guaranteed to be practically unique. This tool generates RFC 4122 version 4 (random) UUIDs in your browser using a secure random source.

UUIDs (also called GUIDs) are everywhere in modern software: database primary keys, distributed system identifiers, API request IDs, and file names. Their key advantage is that they can be generated independently on different machines without coordination, yet remain unique.

Common UUID Formats

Standard: 550e8400-e29b-41d4-a716-446655440000 — lowercase with hyphens.
GUID (Microsoft): {550E8400-E29B-41D4-A716-446655440000} — uppercase, wrapped in braces.
Compact: 550e8400e29b41d4a716446655440000 — no hyphens, useful for URLs and keys.