How to use the UUID Generator
- 1. Choose a versionv4 for random IDs, v7 for database keys, v5 for the same ID from the same name.
- 2. Set the formatHow many, uppercase, no hyphens, braces, or quoted for code.
- 3. GenerateCopy or download the list, or paste a UUID to inspect it.
Which version to use
A UUID is a 128-bit identifier written as 32 hex digits in the pattern 8-4-4-4-12. Version 4 is 122 random bits; this tool takes them from your browser's cryptographically secure generator. Version 7 (added in RFC 9562 in 2024) starts with a 48-bit millisecond timestamp followed by random bits, so new IDs sort after older ones. That keeps database indexes compact, which is why v7 suits primary keys. IDs made in the same millisecond still come out in order. Version 5 is a SHA-1 hash of a namespace and a name, so the same input always gives the same UUID. Everything runs in your browser; nothing you type or choose is uploaded.
The inspector reads any UUID and reports its version and variant, and for v1 and v7 the time it was created.
Worked example
Choose version 5, the DNS namespace and the name uncodemy.com, and the tool gives cd1ca000-b3d1-51ae-8aed-5017f9909421 every time, on any device or programming language. As a check, the name python.org gives 886313e1-3b8a-5372-9b90-0c9aee199e5d, the same value shown in Python's own uuid documentation. Paste the first one into the inspector and it reports version 5 (name-based, SHA-1) with the standard RFC 9562 variant.
Good to know
- v7 reveals when a record was created; use v4 where that must stay private.
- v5 isn't secret: anyone with the namespace and name can recreate it.
- Store UUIDs in a native UUID column (PostgreSQL
uuid, orBINARY(16)in MySQL) rather than text, to save space.
Frequently asked questions
Can two v4 UUIDs ever be the same?
In theory yes, but with 122 random bits the chance is negligible for any real system.
Are UUIDs sent anywhere?
No. They're generated in your browser and never leave it.
Is the UUID generator free?
Yes. You can open the UUID generator and fill in every option without signing up. When you generate UUIDs for the first time, we ask once for your name and WhatsApp number; after that it, and every other Uncodemy tool, opens straight away.