UUID / GUID Generator
Generate RFC 4122 compliant UUID v4 identifiers individually or in bulk.
Generate RFC 4122 Compliant UUID v4 Identifiers
A UUID is a 128-bit identifier designed so that two systems can independently mint IDs that will never collide, without coordinating through a central authority. That property makes them the default choice for distributed systems, offline-first clients, database primary keys and correlation IDs in logging pipelines.
Version 4 UUIDs are the random variant: 122 bits of randomness with six bits fixed to identify the version and variant. This generator sources that randomness from crypto.getRandomValues(), so the identifiers are cryptographically random rather than merely pseudo-random — which matters when a UUID also needs to be unguessable.
Key features
- Cryptographically random — backed by the Web Crypto API, using native crypto.randomUUID() where available.
- Bulk generation — produce up to 1,000 identifiers in a single click.
- Format options — lowercase, uppercase, braced GUID form, or stripped of hyphens.
- Copy or download — copy the whole batch to your clipboard or save it as a plain text file.
This tool runs entirely inside your browser using native Web APIs. Your files and text are never uploaded to a server, never logged and never shared with third parties.
How to use: UUID / GUID Generator
- Choose how many you need
Generate one for a quick test, or set a bulk count when seeding a database or fixture file. - Pick a format
Standard lowercase with hyphens is the RFC form. Uppercase and braced variants suit Microsoft and .NET conventions. - Generate
New identifiers are produced instantly using your browser’s cryptographic random source. - Copy or download
Copy the list to your clipboard, or download it as a .txt file for import elsewhere.
Technical specifications
| Processing location | Entirely in your browser — no server round trip |
|---|---|
| Data uploaded | None. Files and text never leave your device |
| Price | Free — no account, no trial, no usage cap |
| Category | Security |
| Works offline | Yes, once the page has loaded |
| Browser support | Chrome 90+, Edge 90+, Firefox 90+, Safari 15+ |
| Interface languages | English, 中文, हिन्दी, Español, العربية |
Frequently asked questions
What is the chance of two UUID v4 values colliding?
Vanishingly small. With 122 random bits you would need to generate roughly 2.7 × 10¹⁸ UUIDs before reaching a 50% chance of a single collision. In practice, collision is not a risk you need to design around.
What is the difference between a UUID and a GUID?
None technically — GUID is Microsoft’s name for the same 128-bit standard. The only difference is presentation convention: GUIDs are often written in uppercase and wrapped in braces.
Should I use a UUID as a database primary key?
It is a reasonable choice for distributed systems, but random UUIDs scatter inserts across a B-tree index, which hurts write performance at scale. UUID v7, which is time-ordered, is the modern answer if you need both uniqueness and index locality.
Are UUID v4 values safe to use as secret tokens?
When generated from a cryptographic source like this one, 122 bits of entropy is genuinely unguessable. Be careful though — many UUID libraries use non-cryptographic randomness, and those must never be used as security tokens.