UUID Generator
Generate batches of UUID v4 values with secure browser randomness.
Generate up to 100 UUID v4 values at once, choose casing or remove hyphens, then copy or download the result.
Tool area
The real limits on count and format
Entering more than 100 or less than 1 in the count field is automatically clamped back into range: type 500 and click generate, and the field silently resets to 100 while only 100 UUIDs are produced. Entering 0 or a negative number resets it to 1. This limit is hard-coded, not an adjustable preference.
The format control is a single dropdown with three mutually exclusive options: lowercase (default, e.g. 3fa85f64-5717-4562-b3fc-2c963f66afa6), uppercase, or no hyphens. There is no way to select uppercase and no-hyphens at the same time; if you need that combination, generate the list first and then run a find-and-replace in a text editor.
- Verification method: check the lowercase output against the regular expression ^[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$, which confirms UUID v4 format (the third group starts with 4, the fourth starts with 8, 9, a, or b).
What happens if generation fails, and what a UUID should not be used for
Generation relies on the browser's crypto.randomUUID(), which requires a secure context such as HTTPS or localhost. If the browser lacks support or the page is not served securely, the tool catches the exception, clears the output field, and shows an error such as "UUID generation is unavailable in this browser." instead of silently falling back to a weaker random source.
A UUID is not a field type that the CSV to JSON or JSON to CSV converter fills in automatically; when a converted dataset needs identifiers, the usual workflow is to generate a batch on this page first and paste the values into the matching column by hand. A UUID also proves nothing about authorization and should not replace a password, API key, or signature.
How to use
- Choose how many UUIDs you need.
- Choose an output format.
- Generate, copy, or download the values.
Use cases
- Create identifiers for test fixtures.
- Prepare sample database primary keys.
Who is it for
- Developers creating test data and database fixtures
- QA and design teams needing temporary unique identifiers
- Students learning UUID formats and use cases
Real examples
Generate keys for test fixtures
Generate the same number of UUIDs as your fixture records and keep the standard lowercase hyphenated form unless the target schema requires otherwise. Verify that the surrounding fixture contains no real user data before committing it.
Test identifier validation
Create standard, uppercase, and no-hyphen variants to test what an application accepts. UUIDs are identifiers, not authentication secrets, passwords, or proof that a request is authorized.
Good to know
- The tool creates UUID v4 values, not name-based, time-ordered, or database-specific UUID variants.
- Removing hyphens or changing case alters representation only; it does not add randomness.
- For large or regulated systems, generate and validate identifiers in the application or database at write time.
FAQ
- Are these UUID v4 values?
- Yes. Values come from the browser crypto.randomUUID API.
- Can UUIDs be used as passwords?
- No. UUIDs are identifiers, not a password format.
Privacy & local processing
🔒 This tool runs entirely in your browser. No data is uploaded to any server.
All input and files are processed only in this browser tab and are not uploaded to a server.
Trust & usage note
This tool runs mainly in your browser. Your input is not actively uploaded to a server. Avoid entering highly sensitive data. Results are for reference only.
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