Generator

UUID Generator

Generate random UUID v4 values for identifiers, database records, test data, and development workflows.

About UUID v4 identifiers and common questions

What is a UUID?

Overview

A UUID is a Universally Unique Identifier: a standardized identifier format designed to be unique across systems without needing a central sequence generator.

UUID v4 values are randomly generated. They are commonly used when applications need unique IDs for records, requests, test data, files, imports, sessions, or distributed systems.

Where it is used

  • Database records and primary keys
  • API identifiers and request correlation IDs
  • Distributed systems and event messages
  • Test fixtures, mock data, and seed data
  • File names, import records, and temporary IDs
  • Tracing, logging, queues, and background jobs

Key facts

  • A standard UUID contains 32 hexadecimal characters.
  • UUIDs are commonly displayed in five groups separated by hyphens.
  • UUID v4 is random-based rather than sequence-based.
  • UUIDs are usually case-insensitive when compared as hexadecimal values.
  • Removing hyphens makes the value shorter but less recognizable as a standard UUID format.
  • UUIDs are identifiers, not secrets.

Examples

Standard UUID v4

The standard format uses 32 hexadecimal characters shown in five hyphen-separated groups.

ScenarioGenerate one UUID
Output550e8400-e29b-41d4-a716-446655440000

Compact UUID

A compact UUID removes separators while keeping the hexadecimal characters.

ScenarioGenerate without hyphens
Output550e8400e29b41d4a716446655440000

Uppercase UUID

Uppercase output can be useful when a system, document, or existing convention expects uppercase identifiers.

ScenarioUppercase enabled
Output550E8400-E29B-41D4-A716-446655440000

Bulk test data

Generating multiple UUIDs is useful for fixtures, mock data, imports, and development workflows.

ScenarioCount: 10
ResultA list of 10 UUID values

Common mistakes

  • Using UUIDs as passwords, API keys, or security tokens.
  • Assuming a UUID is meaningful or sortable by creation time when using UUID v4.
  • Removing hyphens when another system expects the standard hyphenated format.
  • Mixing uppercase and lowercase formats in systems that compare IDs as plain strings.
  • Using UUIDs where short human-readable IDs would be easier for users.
  • Assuming UUIDs prevent all possible data duplication or business logic conflicts.

Limitations

  • UUID v4 values are not designed to be readable or memorable for humans.
  • UUID v4 values do not naturally show creation order.
  • Random identifiers can be larger and less compact than numeric IDs.
  • UUIDs identify values, but they do not prove authorization, ownership, or authenticity.
  • Some databases and indexes may require planning when using random UUIDs at large scale.

Technical details

UUID v4 format

A standard UUID is commonly displayed as 8-4-4-4-12 hexadecimal characters.

In UUID v4, specific bits identify the version and variant, while the remaining bits are random.

Hyphenated vs compact output

Hyphenated UUIDs are easier to recognize and match the common display format.

Compact UUIDs remove hyphens for systems that require a continuous string.

Identifiers vs secrets

UUIDs are useful identifiers, but they should not be treated as confidential credentials.

Use proper authentication, authorization, and token generation for security-sensitive values.

Frequently asked questions

What does UUID stand for?

UUID stands for Universally Unique Identifier. It is a standardized identifier format used to create unique values across systems.

What is UUID v4?

UUID v4 is a random-based UUID version. It is commonly used when applications need unique identifiers without relying on a central counter.

Can a UUID be duplicated?

A duplicate UUID v4 is extremely unlikely when generated correctly, but no random system can be described as absolutely impossible to collide.

Should UUIDs include hyphens?

The standard display format includes hyphens. Removing hyphens is acceptable only when the receiving system expects or allows compact UUID strings.

Are uppercase and lowercase UUIDs different?

As hexadecimal values, they usually represent the same identifier. However, some systems compare IDs as plain strings, so consistent formatting is important.

Can I use a UUID as a password or secret token?

No. UUIDs are identifiers, not secrets. Security-sensitive tokens should be generated and handled with security-specific requirements.

Private by design

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UUID v4 • Hyphenated • Lowercase

Generated UUIDs

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Guide

How to use the UUID Generator

Use this tool to generate random UUID v4 values for identifiers, database records, test data, fixtures, and development workflows.

Generate one or many UUIDs

Set the count to create a single UUID or generate a list of multiple UUIDs at once for bulk testing, seed data, or temporary identifiers.

Choose the output format

Keep standard hyphenated UUIDs, remove hyphens for compact values, or switch the result to uppercase when a system expects that format.

Common use cases

UUIDs are commonly used for database keys, API identifiers, request tracing, import records, mock data, and distributed systems where unique values are needed.

UUID v4 format

UUID v4 values are randomly generated identifiers. A standard UUID contains 32 hexadecimal characters, usually displayed in five groups separated by hyphens.