UUID Generator

When should you use UUIDs?

UUIDs are useful for test data, request IDs, database keys, API examples, and client-side prototypes where globally unique-looking identifiers are needed.

This tool generates UUID v4 values with browser crypto APIs. It does not send generated IDs anywhere.

Inside a v4 UUID

A UUID, or Universally Unique Identifier, is a 128-bit value standardized in RFC 4122 and its 2024 successor RFC 9562. It is usually written as 32 hexadecimal digits split into five groups of 8-4-4-4-12, separated by hyphens, for 36 characters total. Two of those hex digits are not random: the first character of the third group is the version number, and the first character of the fourth group is the variant, which for RFC 4122 UUIDs is always 8, 9, a, or b.

This generator produces version 4 UUIDs only. When available, it calls the browser crypto.randomUUID() method directly. Where that API is missing, it falls back to filling 16 bytes with crypto.getRandomValues() and then forcing the version and variant bits with (bytes[6] & 0x0f) | 0x40 and (bytes[8] & 0x3f) | 0x80. Both paths draw from the operating system cryptographically secure random number generator rather than Math.random(), which is not designed to resist prediction.

Name-based versions 3 and 5 also exist, hashing a namespace and a name with MD5 or SHA-1 so the same input always produces the same UUID, but this generator does not create those either. Every value this tool outputs is version 4: fully random, never derived from time or from anything typed into the page.

Worked example: reading a UUID

A UUID produced by this tool might look like this:

Generating five UUIDs with the quantity field and comma-separated output produces a single line such as b654289d-6c84-4e88-9aa2-d02939d62318, b9d0f53d-4c76-4bc0-8ce6-f0f6b148acaa, and so on. Every value in a batch is independent; there is no shared prefix or counter linking them, unlike an auto-incrementing database ID.

Limits and gotchas

• Only v4 is generated. If a project specifically needs a time-sortable v7 identifier for database index locality, or a deterministic v3/v5 identifier derived from a name, this tool cannot produce them; it always outputs random v4 values.
• Quantity is capped at 500 per click. The quantity field is clamped between 1 and 500; a larger batch means clicking Generate UUIDs more than once, and each click replaces the previous output rather than appending to it.
• Output is not deduplicated on screen. The tool does not scan a batch for repeats before displaying it. This is not a practical concern for v4, since the chance of any collision among 500 values is astronomically small, but the displayed list carries no uniqueness proof beyond that probability.
• No quoting for code paste-in. The comma-separated and line-separated output formats are plain text; pasting directly into a SQL VALUES list or a JSON array still requires adding quotes around each UUID.
• Secure context dependency. Both crypto.randomUUID() and crypto.getRandomValues() require a secure context, meaning HTTPS or localhost; on an insecure origin neither generation path is available.

Frequently Asked Questions

Is this UUID Generator free?

Yes. You can generate and copy UUIDs without signup.

Are UUIDs generated locally?

Yes. Generation happens in your browser with native crypto APIs, either crypto.randomUUID() or a getRandomValues() fallback.

Which UUID version is generated?

This tool generates UUID v4 values only. It does not generate v1, v3, v5, or v7 UUIDs.

Can I generate UUIDs in bulk?

Yes. The quantity field allows up to 500 UUIDs per click; each click replaces the previous output rather than appending to it.

Are generated UUIDs stored?

No server-side upload endpoint is used for this UUID generation flow. UUIDs are generated and displayed locally in your browser.

What do the version and variant characters in a UUID mean?

In the canonical 8-4-4-4-12 form, the first character of the third group is the version (4 for this tool), and the first character of the fourth group is the variant, always 8, 9, a, or b for RFC 4122 UUIDs.

Can two generated UUIDs collide?

In theory yes, in practice effectively never. A v4 UUID has 122 random bits, so generating even millions of values keeps the collision probability far below anything likely to occur at the 500-per-click volumes this tool supports.

Is a UUID the same as a GUID?

Yes for practical purposes. GUID is the term Microsoft popularized for the same 128-bit identifier format; a value produced by this tool is a valid GUID as well as a valid UUID.

Privacy

Privacy build: This build removes ads, analytics, remote fonts, runtime CDN scripts, and file-operation telemetry. Selected files are processed in the browser using local JavaScript and browser APIs.

ConvertUnlimited does not provide a server-side upload endpoint for this UUID generation flow. UUIDs are generated locally in your browser.

Terms of Use

ConvertUnlimited is provided as is. Review generated identifiers before using them in production systems.