Development · free tool

Free UUID v4 generator for APIs, databases and test data

Generate UUID v4 identifiers for databases, APIs, fixtures and distributed systems.

1–100 UUID v4 values
Hyphenated or compact
Uppercase option
Generated locally

Your tool

UUID Generator

Number of UUIDs Uppercase Without hyphens

Result

Good to know

A UUID is a 128-bit identifier used to create unique references across databases, APIs, logs, events and distributed systems.

Use it well

How to use UUID Generator

Common use cases

API fixtures: Create stable IDs for sample users, orders, payments or events.
Database testing: Fill records with unique identifiers without relying on production data.
Distributed systems: Prepare identifiers that do not require a central sequence.

Steps

Choose how many UUIDs to generate.
Enable uppercase or compact output if needed.
Generate the values.
Copy the result into your fixture, script or payload.

Limits and good practices

Good practices

Use realistic test values when validating forms, exports or API payloads.
Keep real customer, banking and production secrets out of public tools.
Check the output format before copying it into a production workflow.
Document whether a value is generated, validated, converted or only estimated.

Common mistakes

Confusing valid format with real-world validity: A generated or locally validated value can match a format without proving that it exists in an official system.
Using real production data: Public utilities are best for test data, demos, fixtures, QA and quick checks, not for confidential values.

FAQ

Frequently asked questions

What is a UUID v4?

A UUID v4 is a randomly generated 128-bit identifier commonly used as a unique key in software systems.

Is a UUID the same as a GUID?

GUID is Microsoft’s common name for the same type of identifier. In most web and database workflows, UUID and GUID refer to equivalent values.

Can two UUIDs be identical?

A collision is theoretically possible but extremely unlikely when UUID v4 values are generated correctly.

Should UUIDs be uppercase or lowercase?

Both forms are normally accepted. Lowercase with hyphens is the most common representation in APIs and databases.

Are my inputs sent to a server?

OnSubmit tools run in the browser whenever the task can be processed locally. Avoid pasting production secrets, real banking details or personal data into public tools.