b2KIT

UUID / GUID Generator

Generate unique UUIDs (v4) and GUIDs individually or in bulk with one click.

How to Use UUID / GUID Generator

  1. 1

    Select UUID version

    Choose v1, v4, or another UUID version to generate.

  2. 2

    Generate UUIDs

    Click generate to create one or more unique identifiers.

  3. 3

    Copy the UUID

    Click any generated UUID to copy it to your clipboard.

Tested tool guide Developer and data tools Checked July 30, 2026

What UUID / GUID Generator does, with a checked example

This generator creates UUID version 4 values with the browser cryptography API. A UUID is a 128-bit identifier written as hexadecimal groups. Version 4 reserves several bits for the version and variant and fills the remaining bits with random data, making collisions extremely unlikely when values are generated correctly.

Worked example

A concrete input and expected output from the current implementation.

Input

Generate one lowercase UUID with dashes

Expected output

550e8400-e29b-41d4-a716-446655440000

This is a valid version 4 shape: the third group starts with 4 and the fourth group starts with a valid RFC variant digit. Your generated value will be different.

How the result is produced

1

Random bytes come from crypto.getRandomValues

Sixteen random bytes are created in the browser. The version nibble is set to 4 and the variant bits are set to the RFC 4122 variant before hexadecimal formatting.

2

Presentation options do not change uniqueness

Uppercase, lowercase, and removal of dashes change the displayed string only. They do not add entropy or create a different underlying 128-bit value.

Good uses

  • Create identifiers for test data or offline records.
  • Generate correlation IDs for logs and development requests.
  • Prepare unique keys before a client synchronizes with a server.

Limits and checks

  • A UUID is an identifier, not an authentication secret.
  • Database uniqueness constraints are still appropriate.
  • Do not parse business meaning from the random characters.

Common questions

Can two version 4 UUIDs collide?

A collision is mathematically possible but extraordinarily unlikely with a sound random source. Poor or repeated random input raises the risk, which is why this tool uses the browser cryptography API.

Is a GUID different from a UUID?

GUID is terminology commonly used in Microsoft systems. For modern textual version 4 values, the practical format is usually the same UUID representation.

References and verification

The example and behavioral notes were checked against the browser implementation. Standards and primary references below define the relevant format, formula, or platform behavior.

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