UUID Generator

Generate one UUID or up to a thousand at once: random version 4 from the browser's secure random source, time-ordered version 7 that sorts in order of creation, or name-based version 5 from a namespace and a name, which is the same every time. Switch to upper case, drop the hyphens, add braces or quote them as a comma-separated list for code, then copy or download. Paste any UUID to check it and see its version, variant and, for version 7, when it was made.

How it works

UUID Generator is a web page that does its work on your own device. Everything you type or choose is worked out by your browser and never sent to a server, so nothing is stored and there is nothing to delete. There is no account, no sign-up and no limit on how often you use it.

Straight to one job

UUID v4 Generator · GUID Generator

What a UUID is

A UUID, or GUID in Microsoft's vocabulary, is a 128-bit identifier written as 32 hexadecimal digits in five groups, made so that anyone can generate one anywhere without a central registry and still be sure it is unique. Databases use them as keys, APIs as request and object ids, and file formats as the names of things that must not clash when merged. The current standard is RFC 9562, which defines the versions this page makes.

Versions 4, 7 and 5

Version 4 is random: 122 bits from the browser's secure random source, which is what most people want for an id. Version 7 starts with the time it was made, to the millisecond, followed by random bits; ids made later sort after ids made earlier, which keeps database indexes tidy and is why newer systems prefer it. Version 5 is deterministic: the same namespace and name always give the same UUID, computed with SHA-1, so two systems can agree on the id of "https://example.com/thing" without talking to each other. The standard namespaces for URLs, DNS names, OIDs and X.500 names are offered, or use a UUID of your own. The nil UUID, all zeros, is the special value some systems use to mean none.

Formats

The canonical form is lower-case with hyphens. Some systems want upper case, some want the 32 digits with no hyphens, and Windows and .NET often show GUIDs in braces; the ticks change the output without changing the value. Quoted, comma separated gives a list ready to paste into code or a SQL IN clause. Paste any UUID into Check a UUID to see its version and variant, and for version 7 the moment it was made.

What this tool does not do

• It does not make version 1 UUIDs, which embed a network card address; version 7 gives time ordering without revealing anything about the machine.
• It does not keep a list. UUIDs you generate exist only on this page until you copy them.

What it does

• Version 4 random, version 7 time-ordered, version 5 from a name, and nil
• One to 1,000 at a time
• Lower or upper case, with or without hyphens, in braces, quoted for code
• Copy all or download as a text file
• Check any UUID: version, variant, creation time for version 7
• Made with the browser's secure random source and SHA-1
• No upload, no account, no sign-up

Questions

What is the difference between UUID v4 and v7?

Version 4 is entirely random. Version 7 begins with the time it was made, to the millisecond, then random bits, so ids sort in the order they were created, which keeps database indexes compact and makes rows easy to order. Use v7 for new database keys and v4 where no ordering is wanted.

Are these UUIDs unique?

Version 4 has 122 random bits from the browser's cryptographic random source; the chance of any two ever being the same is so small it is treated as zero. Version 7 adds the time, and version 5 is unique for a given namespace and name by construction.

What is a GUID?

The same thing as a UUID; GUID is Microsoft's name for it, often shown in upper case and braces. Tick Upper case and In braces for that form.

How do I make the same UUID every time for a name?

Choose version 5, pick the namespace (URL for web addresses, DNS for domain names, or your own UUID) and type the name. The result is computed with SHA-1 and will be identical on any system that follows the standard.

Can I generate many at once?

Yes, up to 1,000 per click, one per line, or quoted and comma separated for pasting into code or a query.

Is there a limit to how many I can make?

No. Generate as many sets as you like; nothing is counted against you and nothing is stored.

Are the UUIDs sent anywhere or logged?

No. They are made by code in your browser from its own random source, and they exist only on the page until you copy them.

Is it free?

Yes, completely free, with no sign-up.

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