UUID v4 Generator Online

Generate cryptographically random UUID v4 identifiers — bulk generation supported

What Is a UUID v4?

UUID v4 (Universally Unique Identifier version 4) is a 128-bit identifier generated using cryptographically secure random numbers. The format is 8-4-4-4-12 hexadecimal characters separated by hyphens, like f47ac10b-58cc-4372-a567-0e02b2c3d479. The 13th character is always 4 (indicating version 4), and the 17th character is 8, 9, a, or b (indicating the UUID variant).

UUID v4 identifiers are used everywhere in software development: primary keys in databases, request correlation IDs in distributed systems, session tokens, API idempotency keys, message queue identifiers, file naming for uniqueness, and anywhere you need a globally unique identifier without coordinating with a central authority. The probability of generating two identical UUID v4 values is astronomically small — you would need to generate 2.71 quintillion UUIDs to have a 50% chance of a single collision.

How to Generate UUID v4 Identifiers

1. Click Generate to instantly create a new random UUID v4
2. Click again for more — each generation produces a unique identifier
3. Use the bulk generator to create multiple UUIDs at once (up to 1000)
4. Copy individual UUIDs or the entire batch to your clipboard
5. Choose format options: uppercase, lowercase, with or without hyphens

Why Use PinusX UUID Generator?

PinusX generates UUIDs with 100% client-side processing using the browser's crypto.randomUUID() API, which provides cryptographically secure randomness. No UUIDs are generated on a server, transmitted, or logged — each one is created locally in your browser tab and exists only on your machine until you use it. This is important because UUIDs are often used as security-sensitive identifiers: session tokens, API keys, database primary keys, and idempotency tokens. In November 2025, jsonformatter.org leaked over 80,000 user credentials from server-side processing. PinusX avoids this entirely by generating everything locally.

Frequently Asked Questions

Are UUID v4 values truly unique?

For all practical purposes, yes. The 122 random bits in a UUID v4 provide 5.3 x 10^36 possible values. The probability of generating a duplicate is negligible — you would need to generate about 2.71 x 10^18 UUIDs to have a 50% chance of one collision. In practice, UUID v4 collisions essentially never happen.

What is the difference between UUID v1 and v4?

UUID v1 is generated from the current timestamp and the machine's MAC address, making it sortable by time but potentially revealing the machine identity. UUID v4 is purely random with no embedded information, providing better privacy. UUID v4 is the most commonly used version in web applications.

Can I use UUIDs as database primary keys?

Yes, but with considerations. UUID v4 primary keys cause index fragmentation in B-tree indexes because they are random. For high-performance databases, consider UUID v7 (time-ordered) or ULID which are sortable. For most applications, UUID v4 works fine and provides the advantage of client-side generation without database coordination.

Should UUIDs include hyphens?

The standard format includes hyphens (8-4-4-4-12), but many systems accept or prefer UUIDs without hyphens (32 hex characters). Both represent the same 128-bit value. Our tool lets you generate in either format. Use the hyphenated format for readability and standard compliance, or remove hyphens for compact storage.

How does crypto.randomUUID() work?

Modern browsers provide crypto.randomUUID() which generates UUID v4 using cryptographically secure pseudorandom number generation (CSPRNG). This is backed by the operating system's entropy source (/dev/urandom on Linux, CryptGenRandom on Windows), providing randomness suitable for security-sensitive applications.

Your data never leaves your browser. 100% client-side processing.