Generate Random Data from a Regular Expression
Quickly generate random data that matches the given regular expression. Runs entirely in your browser, so your data never leaves your device.
0 chars · 0 lines
Output
The result appears here as you type.
How to use Generate Random Data from a Regular Expression
- 1. Paste your regular expression. Enter a pattern like [a-z]{3}-\d{2} into the input pane. The tool reads the pattern's character classes and quantifiers to know what kind of text to produce.
- 2. Set how many strings. Enter How many strings to decide how many independently generated values matching the pattern the tool returns in one run.
- 3. Review the generated strings. The output lists strings that all match your pattern but vary in their actual content, since each one is filled in randomly within what the regex allows.
When to use Generate Random Data from a Regular Expression
Generate Random Data from a Regular Expression works in reverse from a normal regex tool, taking a pattern and producing sample strings that match it instead of testing strings against it. It suits anyone who needs valid-format test data fast.
- Generating test cases for input validation. A developer testing a form field that validates against a specific regex wants a batch of guaranteed-valid sample inputs to confirm the happy path works before testing edge cases.
- Producing sample data matching a legacy ID format. Someone integrating with a system that expects IDs in a fixed pattern, like three letters followed by two digits, wants realistic sample values without inventing each one manually.
- Fuzzing a parser with pattern-conforming input. A developer stress-testing a parser wants many strings that technically match the expected format but vary in content, to check the parser doesn't assume a single fixed value.
- Teaching how regex quantifiers shape output. An instructor explaining regex wants to show students concrete examples of what a pattern like {3} or \d+ actually generates, rather than just describing it abstractly.
Examples
Match a simple pattern
Input
[a-z]{3}-\d{2}Output
wqz-08 kmx-41 …
About the Generate Random Data from a Regular Expression tool
Generate Random Data from a Regular Expression runs as plain JavaScript in your browser tab, with no server behind it. Quickly generate random data that matches the given regular expression. Whatever you put in stays on your device from start to finish.
The tool is part of EditSafely's Random Tools section, 120 single-purpose utilities built around the same idea: open the page, get the result, keep your data to yourself.
You can shape the output with the How many strings setting, and the result refreshes the moment you change it. A worked example further down the page shows exactly what the tool produces for a real input.
That local-first design has practical benefits beyond privacy. The tool keeps working on a flaky connection once the page has loaded, results are instant because nothing round-trips to a server, and it is safe to use with confidential material.
Frequently asked questions
Does Generate Random Data from a Regular Expression cost anything?
Yes, it is completely free. All 2,658 tools on EditSafely work without an account, a subscription or usage limits.
Is it safe to paste sensitive or confidential data?
No data leaves your device. The whole tool is JavaScript that runs inside your browser tab, so there is no upload, no server-side processing and no log of what you did. If you disconnect from the internet after the page loads, it keeps working.
How much text can I process at once?
There is no fixed limit. Because the work happens on your own device rather than on a shared server, the practical ceiling is your machine's memory, which comfortably handles inputs far larger than typical online tools allow.
Do I need to sign up or install anything?
Nothing to install and no account needed. Open the page in any up-to-date browser, including on a phone or tablet, and the tool is ready.
How do I use the result?
The output panel has a one-click copy button, and you can keep refining the input while you work; the result updates in place as you type.