What is the difference between UUID and GUID?

UUID (Universally Unique Identifier) and GUID (Globally Unique Identifier) refer to the same 128-bit identifier format. UUID is the term used in the RFC standard and most programming languages. GUID is the term used primarily in Microsoft ecosystems (.NET, SQL Server, COM). Both use the same 8-4-4-4-12 hexadecimal format.

Which UUID version should I use?

UUID v4 (random) is the most widely used and suitable for most applications. UUID v7 is recommended for database primary keys because its timestamp prefix makes values naturally sortable, which improves index performance. UUID v1 is timestamp-based and useful when you need to extract the creation time from the identifier. UUID v3 and v5 produce deterministic UUIDs from a namespace and name, useful when you need reproducible identifiers.

Are UUIDs truly unique?

UUIDs are designed to be practically unique, not mathematically guaranteed unique. A UUID v4 has 122 random bits, which means the probability of generating a duplicate is astronomically low. You would need to generate about 2.7 quintillion UUIDs to have a 50% chance of a single collision.

UUID Generator - Troubleshooting Tools

Generate unique identifiers (UUID v4 / GUID) in multiple formats.

How UUID Generator Works

What is a UUID?

A UUID (Universally Unique Identifier) is a 128-bit identifier standardized by RFC 9562. UUIDs are designed to be globally unique without requiring a central authority. They are formatted as 32 hexadecimal digits in five groups separated by dashes: xxxxxxxx-xxxx-Mxxx-Nxxx-xxxxxxxxxxxx.

GUIDs (Globally Unique Identifiers) are the same format, commonly used in Microsoft systems.

How to Use

Select a UUID version: v1 (timestamp), v4 (random), v7 (timestamp + random), or Nil.
Choose a format: standard, uppercase, no dashes, braces (GUID), URN, or short (Base64).
Set the quantity (1 to 1000) and click Generate.
Press Ctrl+Enter to generate from the keyboard.
Use the Namespace UUIDs panel to create deterministic v3 (MD5) and v5 (SHA-1) UUIDs.

UUID Versions

v1	Timestamp-based. 100ns intervals since 1582-10-15 plus random node. Sortable by creation time.
v3	Namespace + name hashed with MD5. Deterministic: same input always produces the same UUID.
v4	Fully random. 122 bits of cryptographic randomness. Most widely used version.
v5	Namespace + name hashed with SHA-1. Preferred over v3 for new applications.
v7	Unix timestamp (ms) + random. Ideal for database primary keys (naturally sortable).
Nil	All-zero UUID: 00000000-0000-0000-0000-000000000000

Output Formats

Standard	`550e8400-e29b-41d4-a716-446655440000`
Uppercase	`550E8400-E29B-41D4-A716-446655440000`
No dashes	`550e8400e29b41d4a716446655440000`
Braces	`{550e8400-e29b-41d4-a716-446655440000}`
URN	`urn:uuid:550e8400-e29b-41d4-a716-446655440000`
Short	`VQ6EAOKbQdSnFkRmVUQAAA` (22-char URL-safe Base64)

Privacy & Security: All UUIDs are generated entirely in your browser using the Web Crypto API. No data is sent to any server.

Version

Format

Quantity

Output

Preset

Namespace UUID

Name

Output Deterministic v3 (MD5) and v5 (SHA-1)

v3 (MD5)

v5 (SHA-1)

UUID Generator

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