UUID v4 Generator | Free Secure Online UUID Generator

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Use our free UUID v4 generator to instantly create secure, unique identifiers online. A UUID (Universally Unique Identifier) is a 128-bit value that ensures global uniqueness, making it ideal for databases, APIs, tokens, and distributed systems.

Generate UUID v4




What is a UUID (Universally Unique Identifier)?

A UUID is a standardized 128-bit number used to uniquely identify information across systems without collisions. UUIDs are represented as a 36-character string, for example:

123e4567-e89b-12d3-a456-426614174000

How Does Our Free UUID v4 Generator Work?

UUID v4 is the most common type and is generated using cryptographically secure random numbers. The structure follows this format:

xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx
  • x = random hex digit (0–f)
  • 4 = indicates version 4
  • y = one of {8, 9, a, b} indicating variant

Why Use an Online UUID Generator?

UUIDs solve the problem of unique identification without central coordination. They are widely used in:

  • Databases – as primary keys in distributed systems
  • APIs – request IDs, access tokens, and session identifiers
  • Security – generating salts, keys, and authentication tokens
  • File Systems – unique identifiers for uploaded files
  • E-commerce – order numbers and transaction IDs

Security of UUID v4

UUID v4 uses cryptographically strong randomness with crypto.getRandomValues, making collisions nearly impossible. The total possible UUIDs is:

2^128 ≈ 3.4 × 10^38

Even if billions of UUIDs are generated per second for years, the chance of duplication is effectively zero.

Collision Probability Formula

The probability of a collision after n UUIDs is approximately:

P ≈ n² / (2 × 2^122)

For example:

  • After 1 billion UUIDs → Probability ≈ 1 in 10^20
  • Practically zero in real-world scenarios

How to Use This UUID Generator

  1. Enter how many UUIDs you want to generate
  2. Click “Generate UUIDs”
  3. Copy them into your project, API, or database

Real-World Examples of UUID Generators

  • Web development: Assigning unique IDs to users or sessions
  • Distributed databases: Ensuring globally unique primary keys
  • Authentication: API keys and secure tokens
  • IoT devices: Device identifiers in large networks

FAQs

Is UUID v4 truly unique?

Yes. With 2^128 possible values, collisions are statistically impossible for practical use cases.

Is UUID v4 secure?

UUID v4 uses strong randomness, making it secure for identifiers. However, avoid using it as a sole security mechanism—combine with encryption and HTTPS.

When should I use UUIDs instead of incremental IDs?

Use UUIDs when working with distributed systems, APIs, or databases where centralized incrementing IDs may clash.

Need a simpler way to generate secure values like passwords or tokens? Try our Random String Generator for fully customizable strings.