Free Toolkit

UUID GeneratorGenerate cryptographically secure UUID v4 identifiers.

UUID Generator illustration
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UUID Generator

Generate cryptographically secure UUID v4 identifiers.

How to Use
1

Set Options

Choose quantity, uppercase, and dash-removal options.

2

Generate

Type anything to generate UUIDs with your settings.

3

Copy UUIDs

Copy the generated UUIDs from the output.

What Is UUID Generator?

A UUID (Universally Unique Identifier) generator creates version 4 UUIDs — 128-bit identifiers that are practically unique across all systems without requiring a central registry. UUID v4 uses cryptographically secure random numbers to generate identifiers with an astronomically low collision probability (1 in 2^122). UUIDs are formatted as 32 hexadecimal digits in 5 groups separated by hyphens: 8-4-4-4-12 (e.g., 550e8400-e29b-41d4-a716-446655440000). This tool uses your browser's crypto.randomUUID() API for maximum security.

Why Use Our UUID Generator?

  • Cryptographically secure UUID v4 generation
  • Uses browser's native crypto.randomUUID() API
  • Options for uppercase, no-dashes, and bulk generation
  • Collision probability is astronomically low (1 in 2^122)
  • Completely client-side — nothing sent to servers

Common Use Cases

Database Primary Keys

Generate UUIDs for use as unique primary keys in databases without auto-increment.

API Identifiers

Create unique resource identifiers for REST APIs and microservices.

Session Tokens

Generate unique session identifiers for user authentication systems.

File Naming

Create unique file names to prevent collisions in storage systems.

Technical Guide

UUID v4 generation uses the Web Crypto API's crypto.randomUUID() method, which produces a RFC 4122-compliant version 4 UUID. The 128-bit UUID has 6 bits reserved for version (0100) and variant (10xx), leaving 122 random bits. This gives approximately 5.3 × 10^36 possible UUIDs. The standard format is 8-4-4-4-12 hexadecimal characters separated by hyphens. The no-dashes option simply removes the hyphens for a 32-character hex string. Uppercase option converts all hex digits to uppercase. With 122 bits of randomness, you would need to generate about 2.7 × 10^18 UUIDs to have a 50% chance of a collision.

Tips & Best Practices

  • 1
    UUID v4 is the most common type — suitable for most applications
  • 2
    Remove dashes for compact storage in databases
  • 3
    UUIDs are case-insensitive per spec, but lowercase is conventional
  • 4
    For ordered IDs, consider ULID which is timestamp-sortable
  • 5
    Generate bulk UUIDs for batch database seeding or testing

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Frequently Asked Questions

QWhat version of UUID does this generate?
Version 4 (random). You can identify v4 UUIDs by the "4" in the third group: xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx.
QCan UUIDs collide?
Theoretically yes, but the probability is about 1 in 2^122 (5.3 × 10^36). For practical purposes, collisions are impossible.
QWhat's the difference between UUID and GUID?
GUID (Globally Unique Identifier) is Microsoft's name for UUID. They are functionally identical.
QShould I use UUIDs for database primary keys?
UUIDs work well but are larger than auto-increment integers (16 bytes vs 4-8). Consider ULID for time-ordered unique IDs.
QAre UUIDs secure enough for tokens?
UUID v4 has 122 bits of randomness and is generated with crypto.randomUUID(), making it suitable for most security applications.

About UUID Generator

UUID Generator is a free online tool from FreeToolkit.ai. All processing happens directly in your browser — your data never leaves your device. No registration required. No ads. Just fast, reliable tools.