UUID Validator and Inspector

Validate a UUID or GUID online and detect its version and variant — free UUID checker.

About

About the UUID Validator and Inspector

Checks whether a UUID is correctly formatted, then identifies its version and variant.

Backend developers use it to confirm an identifier they're debugging is actually a well-formed UUID and see which version generated it, while QA engineers use it to check that a system is producing the UUID version it's supposed to. It's one of many free data tools on Toolapt, and like every tool here, it's free to use with no sign-up and no limit on how many times you run it.

Choose what to view about this tool

Guide

Using the UUID Validator and Inspector

  1. 1

    Step 1

    Paste the UUID into the UUID field.

  2. 2

    Step 2

    Click "Check".

  3. 3

    Step 3

    Read whether it's valid, plus its version, variant and uppercase form.

  4. 4

    Step 4

    Click "Clear" to check another UUID.

  • Validates the standard 8-4-4-4-12 hexadecimal UUID format
  • Identifies the UUID version (1 through 5) from the version digit
  • Identifies the variant: RFC 4122 standard, NCS backward-compatible, or Microsoft GUID
  • Flags the special all-zero nil UUID
  • Shows the uppercase form of the UUID for systems that expect that casing
  • Works entirely in your browser — nothing you paste is sent to a server
  • Free to use, with no sign-up and no limit on how many times you run it

Backend developers

Backend developers use the UUID Validator for confirming an identifier they're debugging is a well-formed UUID and seeing which version generated it.

QA engineers

QA engineers use the UUID Validator for checking that a system under test is producing the UUID version and variant it's supposed to.

Database administrators

Database administrators use the UUID Validator for spot-checking a primary key value pasted from a query result.

Students learning UUIDs

Students learning UUIDs use the UUID Validator for seeing how the version and variant digits are actually encoded inside the format.

Examples

UUID Validator and Inspector examples

4 worked examples

01

Checking a well-formed UUID

Pasting 550e8400-e29b-41d4-a716-446655440000 and clicking Check reports it as valid, version 1, RFC 4122 variant, with the uppercase form 550E8400-E29B-41D4-A716-446655440000.

02

Identifying a random UUID

Pasting 3f2504e0-4f89-41d3-9a0c-0305e82c3301 identifies it as version 4 (random), RFC 4122 variant.

03

Spotting the nil UUID

Pasting 00000000-0000-0000-0000-000000000000 is flagged as the special nil UUID rather than assigned a normal version and variant.

04

Catching a malformed UUID

Pasting a string with the wrong number of hex digits or missing hyphens, like 550e8400-e29b-41d4-a716, is reported as invalid instead of being assigned a version.

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FAQ

Frequently asked questions

Quick answers to common questions about the UUID Validator and Inspector.

What does the UUID Validator and Inspector do?

It checks whether a UUID is correctly formatted, and identifies its version and variant.

Is the UUID Validator free to use?

Yes. It's free, with no sign-up, no watermark and no limit on how many times you use it.

Is my UUID safe when I use this tool?

Yes. Validation happens entirely on your own device — nothing you paste is sent to a server.

What format does a valid UUID need to be in?

32 hexadecimal digits arranged as 8-4-4-4-12 characters separated by hyphens, like 550e8400-e29b-41d4-a716-446655440000.

What do UUID versions 1 through 5 mean?

They indicate how the UUID was generated — for example, version 1 is time-based, version 4 is random, and version 5 is generated from a name using SHA-1 hashing. The tool reads this from a single digit in the UUID.

What does the variant tell me?

It indicates which layout rules the UUID follows for its remaining bits. Almost all UUIDs generated today use the RFC 4122 standard variant; the others are rarer, older or vendor-specific layouts.

What is the nil UUID?

It's the special all-zero UUID (00000000-0000-0000-0000-000000000000), often used to represent "no value" in systems that expect a UUID field.

Can I use this tool on my phone?

Yes. The page is fully responsive and works on mobile, tablet and desktop browsers alike.

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