UUID Generator Online: v4, Batch, and GUID
Generate UUID v4 online and in batches: RFC 4122 format, how random v4 works, the UUID vs GUID relationship, and common uses like test data and placeholder IDs.
When you need 50 unique IDs for test data, a UUID primary key for a database column, or example values for API documentation, the online UUID generator covers the job: up to 100 RFC 4122 UUID v4 values per run, generated locally in your browser, one per line, with one-click copy. We ran a 100-value batch and verified the format and the count limit before writing this guide. The guide explains the UUID format, how v4 differs from other versions, and whether GUID and UUID are the same thing.
What a UUID looks like
A UUID (Universally Unique Identifier) is a 128-bit identifier, usually written as 8-4-4-4-12 hexadecimal digits, for example:
550e8400-e29b-41d4-a716-446655440000
RFC 4122 defines several versions: v1 uses a timestamp and node information, v3/v5 are derived from name hashes, and v4 uses random numbers. In v4, 122 bits come from random data and the remaining 6 bits are fixed to mark the version and variant. See RFC 4122 for the specification.
Because v4 draws from a cryptographically secure random source, the collision probability is extremely low, so v4 is a fine default for most "generate a unique ID" needs.
Generating UUIDs in batches
- Open the online UUID generator and enter a count between 1 and 100.
- Click "Generate" — each line of output is a UUID v4.
- Click "Copy" and paste the values into your test scripts, table definitions, or API docs.
The tool prefers the browser's crypto.randomUUID() and falls back to an equivalent random v4 algorithm in older browsers; see MDN's crypto.randomUUID() documentation for details.
Batch generation is most often used for test data. When writing API tests, combine it with the JSON formatter to inspect responses and the JWT decoder to read token payloads, and you can assemble a full integration-test dataset with unique IDs quickly.
What is the difference between GUID and UUID?
There is no practical difference. GUID (Globally Unique Identifier) is Microsoft's name for the same kind of identifier, following the same 128-bit format and RFC 4122 system. When a project asks for a "GUID," a UUID v4 from this tool works directly in Windows and .NET ecosystems.
Note the difference between UUID and hash: a hash is computed from input, so the same input always produces the same output; a UUID v4 is a random identifier that carries no input information. For more on hashes and their use cases, read the MD5 vs SHA256 hash guide.
Frequently asked questions
Which UUID version is generated?
The tool uses crypto.randomUUID() to generate UUID v4, with a fallback to an equivalent random v4 algorithm in older browsers.
What is the difference between UUID and GUID?
GUID is Microsoft's name for the same kind of identifier. This tool generates RFC 4122 UUID v4 values, which fit most GUID use cases directly.
How many can I generate at once?
Up to 100 per run; generate in batches if you need more.
Is my data uploaded?
No. Everything runs locally in your browser; generated IDs are never sent to any server.
Generate a batch now
Open the UUID generator, generate 10 values as API test data first, confirm the format matches your expectation, then scale up as needed. As long as everyone uses the same RFC 4122 format, the IDs work across languages and platforms.
References
[1] RFC 4122 — UUID specification: https://www.rfc-editor.org/rfc/rfc4122 [2] MDN — crypto.randomUUID(): https://developer.mozilla.org/en-US/docs/Web/API/Crypto/randomUUID