What is a UUID and why is it used?

A UUID (Universally Unique Identifier) is a 128-bit number used to uniquely identify information in computer systems. UUIDs are essential in distributed systems where multiple systems need to generate unique identifiers without coordinating with each other.

What is the difference between UUID versions?

UUID versions differ in generation method: v1 uses timestamp + MAC, v3 uses MD5 hashing, v4 uses random numbers, v5 uses SHA-1 hashing, v6 reorders v1 fields, v7 uses Unix timestamp + random bits, and v8 is vendor-specific.

What makes a UUID valid or invalid?

A valid UUID must follow the 8-4-4-4-12 hexadecimal format with hyphens, have valid hex digits (0-9, a-f), a version nibble of 1-8, and variant bits of 8, 9, a, or b for standard RFC 4122 UUIDs.

Can two systems generate the same UUID?

While theoretically possible, the probability is astronomically low for v4 random UUIDs with 122 random bits. You would need to generate over 2 quintillion UUIDs to have a 50% chance of collision.

Should I use UUIDs as database primary keys?

UUIDs offer advantages like distributed generation and no information leakage, but have trade-offs including larger storage and potential index fragmentation. UUID v7 addresses indexing issues while maintaining privacy.

Free developer tool

UUID Validator

Validate UUIDs instantly. Check version, format, and validity. Supports UUID v1 through v8, nil UUIDs, and max UUIDs. Get detailed breakdown of UUID structure.

All UUID VersionsVersion DetectionInstant Results

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Introduction

Free Online UUID Validator

The UUID Validator lets you verify whether a string conforms to the UUID format specification in seconds. Whether you're a developer validating API parameters, a database administrator verifying data integrity, or a QA engineer testing applications, this tool helps you quickly validate and analyze UUIDs.

The validator works directly in your browser, making it fast, secure, and accessible from any device. No registration required, no data stored, and no limits on usage.

About the tool

What is a UUID Validator?

A UUID Validator is an essential developer tool that verifies whether a given string conforms to the Universally Unique Identifier format specification as defined by RFC 4122. It checks the format, version, and variant of UUIDs.

Our validator supports all UUID versions from v1 through v8, including special Nil UUIDs (all zeros) and Max UUIDs (all Fs). It provides detailed analysis including version detection, variant identification, and formatted output options.

Benefits

Why Use Our UUID Validator?

Instant Validation

Validate UUIDs in milliseconds with detailed version and variant analysis.

100% Private

Your UUIDs never leave your browser. All validation happens locally.

All Versions Supported

Validates UUID v1 through v8, plus Nil and Max UUIDs.

Validation History

Track recent validations for quick reference and re-validation.

Technical reference

UUID Versions Reference

UUID v1 - Time-based

Uses timestamp and MAC address

Best for: Legacy systems requiring time-based sorting

UUID v2 - DCE Security

Time-based with POSIX UID/GID

Best for: Legacy DCE systems

UUID v3 - Name-based (MD5)

Generated from namespace and name using MD5

Best for: Deterministic IDs for same input

UUID v4 - Random

Cryptographically random generated

Best for: Most common, general purpose use

UUID v5 - Name-based (SHA-1)

Generated from namespace and name using SHA-1

Best for: Deterministic with stronger hashing

UUID v6 - Reordered Time

Time-based with Gregorian calendar ordering

Best for: Legacy compatibility with time ordering

UUID v7 - Unix Epoch Time

Unix timestamp with random bits

Best for: Modern databases requiring sortable IDs

UUID v8 - Custom/Vendor

Vendor-specific custom format

Best for: Specialized vendor implementations

Target users

Who Should Use This Tool?

Backend Developers

Validate UUID parameters in API endpoints

Database Administrators

Verify UUID format before data insertion

QA Engineers

Validate test data and fixtures

DevOps Engineers

Debug UUID issues in logs and traces

Full-Stack Developers

Quick validation during development

Students

Learn about UUID structure and versions

Practical applications

Real-World Use Cases

API Development

Validate UUID parameters in API requests before processing

GET /api/users/{uuid}

Database Validation

Verify UUID format before database insertion

INSERT INTO users (id) VALUES (?)

Testing & Debugging

Quickly verify UUIDs in test data and logs

Validating test fixtures

Data Migration

Ensure UUID integrity during data transfers

Migrating between databases

Comparison

Why Choose AttachAD?

Feature	Manual Regex	Other Validators
All UUID Versions (1-8)	—	—
Nil/Max UUID Detection	—	—
Variant Detection	—
Version Description	—	—
Format Conversion	—	—
Validation History	—	—
Quick Generate	—	—
Browser Based	—
No Installation
Privacy (Local Processing)		—

FAQ

Frequently Asked Questions

A UUID (Universally Unique Identifier) is a 128-bit number used to uniquely identify information in computer systems without central coordination. It's represented as 32 hexadecimal digits in the format 8-4-4-4-12 (e.g., 550e8400-e29b-41d4-a716-446655440000). UUIDs are essential for distributed systems, database keys, and API identifiers.

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