What is the chance of two UUID v4 colliding?

To have a 50% chance of a single collision, you would need to generate approximately 2.71 quintillion (2.71 × 10^18) UUIDs.

Is there any difference between a UUID and a GUID?

GUID (Globally Unique Identifier) is Microsoft's implementation of the UUID (Universally Unique Identifier) standard defined in RFC 4122. They are functionally identical.

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UUID / GUID v4 Generator

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Generate random UUID v4 values.

100% In-Browser Execution

Quantity:

Include Hyphens (-)Uppercase (A-F)Wrap in Braces {...}Wrap in Quotes ("...")

Generated Identifiers (0)

Understanding UUID Versions & Entropy

UUID v4 (Random)

122 bits of true cryptographic entropy. Standard for session tokens, request IDs, and distributed objects.

UUID v7 (Time-Ordered)

Unix millisecond timestamp + 74 bits of entropy. Optimizes B-tree index locality in PostgreSQL and MySQL.

UUID v1 (Host & Time)

Combines timestamp with host MAC address. Generally avoided today due to device tracking privacy concerns.

Collision Risk

Generating 1 billion UUIDs per second for 85 years yields less than a 50% probability of a single collision.

Tool Documentation, Shortcuts & FAQs

How to Use UUID / GUID v4 Generator

1Choose the quantity of UUIDs to generate (from 1 to 500).
2Select your formatting options: Uppercase/Lowercase, Remove Hyphens, or Add Braces.
3Click 'Generate UUIDs'.
4Click any UUID to copy it individually, or click 'Copy All' to export the batch.

Key Capabilities

Cryptographically Secure

Uses browser crypto.randomUUID() for true cryptographic randomness with zero predictable patterns.

Bulk Generation

Generate 1 to 500 UUIDs in a single instant click.

Formatting Customization

Uppercase, lowercase, hyphenated, no-hyphen, curly braces {guid}, and comma/quote formatting.

Export Options

Copy individual items, copy the full list, or download as a .txt or .json array.

Frequently Asked Questions

A UUID v4 is a 128-bit identifier generated using random or pseudo-random numbers. Out of 128 bits, 122 bits are purely random, making collision probability astronomically low.

Zero Data Retention

All calculations are performed strictly in client-side memory using your browser engine. No data is ever sent across the network.