UUID v4 Generator
Instantly generate random, cryptographically secure version 4 UUIDs entirely within your browser.
What is a UUID (v4)?
A UUID (Universally Unique Identifier), also known as a GUID in the Microsoft ecosystem, is a 128-bit label used for information in computer systems. Version 4 UUIDs are generated using completely random numbers, ensuring astronomical odds against duplication.
How unique is a UUID v4?
There are 2122 (or 5.3×1036) possible v4 UUIDs. The probability of generating a duplicate is so close to zero that it can be safely ignored for all practical software development purposes.
What is a UUID v4?
A UUID (Universally Unique Identifier), sometimes called a GUID (Globally Unique Identifier), is a 128-bit number used to identify information in computer systems. A Version 4 UUID is generated using pseudorandom numbers.
The standard UUID string is represented as 32 hexadecimal (base 16) digits, displayed in five groups separated by hyphens, in the form 8-4-4-4-12 for a total of 36 characters (e.g., 550e8400-e29b-41d4-a716-446655440000).
What is the probability of a collision?
A collision occurs when the same UUID is generated twice. For a version 4 UUID, the probability of this happening is practically zero.
Because v4 UUIDs use 122 random bits (with 6 bits reserved for version and variant information), there are 2122 (or about 5.3 × 1036) possible unique values. To put this into perspective, you would need to generate 1 billion UUIDs per second for about 85 years to reach a 50% chance of a single collision. For all practical software development purposes, you can assume every v4 UUID you generate is globally unique.
Why generate UUIDs locally?
Generating identifiers locally via the Web Crypto API guarantees that no third-party server has a log of the IDs you are provisioning. If you are generating UUIDs for sensitive database migrations, session tokens, or transaction IDs, executing this locally in your browser ensures perfect isolation from network interception.