UUID v4 Generator
UUID v4 Generator: Generate one or many random version-4 UUIDs (RFC 4122). They use the browser's cryptographically-secure random source via crypto.randomUUID(), so they are suitable for identifiers and test data. Choose how many to create and copy them with one click — generation is fully local.
Data as of 2026-06-13.
How it works
A version-4 UUID is a 128-bit identifier whose bits are random except for a few fixed bits that mark the version (4) and variant. It is defined by RFC 4122 and is the most common choice for randomly-generated identifiers.
This generator calls the browser's crypto.randomUUID() where available, which draws from a cryptographically-secure random source, and falls back to building a v4 UUID from crypto.getRandomValues() on older engines. You can produce up to 100 at once and optionally drop the hyphens or uppercase the output.
Runs fully client-side in your browser. Source: published web standards (RFCs and the WHATWG/W3C specifications), as implemented by your browser. Verified 2026-06-13.
Frequently asked questions
Are these UUIDs cryptographically random?
Yes. They use the browser's cryptographically-secure random generator (crypto.randomUUID or crypto.getRandomValues), so they are unpredictable and suitable for identifiers and test data.
Will I ever get a duplicate?
The probability of a collision between random v4 UUIDs is astronomically small for normal volumes — you would need to generate billions before a collision becomes likely. For practical purposes they are unique.
Can I generate UUIDs without hyphens?
Yes. Untick "Include hyphens" to get the 32-character hexadecimal form, and tick "Uppercase" if you need uppercase letters.
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Last updated: 2026-06-13