Generate random UUID version 4 identifiers instantly. UUIDs are universally unique identifiers used in databases, APIs, distributed systems, and more. This tool uses your browser's built-in cryptographic random number generator for maximum randomness. Generate one or up to ten UUIDs at once.
Enter your values to see the result.
Click Generate (count: 1) → 550e8400-e29b-41d4-a716-446655440000
A standard UUID v4 with 36 characters including hyphens.
Generate 5 → 5 unique UUIDs listed vertically
Generate multiple UUIDs at once for batch database inserts or test data.
Generate 10 → 10 UUIDs with Copy All option
Maximum batch size. Use Copy All to grab every UUID at once.
Universally Unique Identifiers are the backbone of modern distributed systems. Every time you create a record in a database, issue an API key, or assign an ID to a message in a queue, you need something that is guaranteed to be unique across all systems, without coordination.
UUIDs solve this problem. A version 4 UUID has 122 bits of randomness, making collisions practically impossible.
The UUID specification defines five versions, each with a different generation strategy:
The "4" in the third group of the UUID (after the second hyphen) indicates the version. The first character of the fourth group indicates the variant (8, 9, a, or b for standard UUIDs).
A UUID consists of 32 hexadecimal digits in five groups:
For version 4, all bits except the version and variant fields are random, giving 122 bits of entropy.
This tool uses the browser's crypto.randomUUID() API, which is part of the Web Crypto API. This function generates a version 4 UUID using the operating system's cryptographically secure random number generator.
If crypto.randomUUID() is not available (in older browsers), the tool falls back to crypto.getRandomValues() with manual version and variant bit setting.
Database primary keys — Use UUIDs as primary keys in distributed databases where auto-incrementing integers would cause conflicts.
API identifiers — Assign unique IDs to API resources, request traces, and correlation IDs.
Session tokens — Generate random session identifiers for web applications.
Test data — Create realistic test data with unique identifiers for development and QA.
File naming — Generate unique filenames to prevent collisions in shared storage systems.
All UUIDs are generated locally in your browser using cryptographic randomness. No data is sent to any server. The quality of randomness depends on your browser and operating system's random number generator, which is the same source used for TLS key generation.
A UUID (Universally Unique Identifier) is a 128-bit value used to uniquely identify information in computer systems. The standard format is 32 hexadecimal digits displayed in five groups separated by hyphens: 8-4-4-4-12. The total length is always 36 characters including hyphens.
UUID version 4 means the identifier is generated using random or pseudo-random numbers. Unlike version 1 (which uses the current timestamp and MAC address) or version 5 (which uses a namespace and name hash), version 4 UUIDs are simply random. The probability of two v4 UUIDs being identical is astronomically small.
This tool uses the browser's crypto.randomUUID() API, which is backed by the operating system's cryptographically secure random number generator. This provides the highest quality randomness available in a browser environment.
Theoretically yes, but the probability is vanishingly small. With 122 random bits in a v4 UUID, you would need to generate about 2.71 × 10^18 UUIDs to have a 50% chance of a single collision. For practical purposes, v4 UUIDs are unique.
No, all UUIDs are generated entirely in your browser using the Web Crypto API. No data of any kind is transmitted to any server, stored in any database, or logged anywhere. The cryptographic randomness comes directly from your device operating system built-in random number generator, ensuring maximum security and complete privacy.
Last updated on 2026-09-26 · Written by UtiliaTools