Generate a String from Regex
Produce random strings that match a 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 a String from Regex
- 1. Enter your regular expression. Type the pattern you want to match into the input pane, such as [a-z]{3}-\d{2}. The tool works the pattern in reverse, building strings that satisfy it rather than testing against it.
- 2. Choose how many to generate. Set How many strings to control the size of the batch. Generating several at once shows you the range of valid values the pattern actually allows.
- 3. Copy the matching strings. Copy the generated strings from the output pane, one per line, into your test fixtures or seed data. Each one is guaranteed to match the pattern you supplied.
When to use Generate a String from Regex
Generate a String from Regex runs a regular expression backwards, producing text that matches the pattern instead of checking text against it. Reach for it whenever you have written a validation regex and need sample data that satisfies it.
- Test data for a validation regex. You wrote a regex to validate order codes like [a-z]{3}-\d{2} and need realistic sample values to feed a unit test without hand-typing a dozen strings.
- Fuzzing an input parser. A parser is meant to accept a specific pattern. Generating a batch of matching strings gives you quick coverage of the pattern's edge cases before writing a full fuzzer.
- Populating a demo form field. A signup form validates phone numbers against a regex. Generate a few example values matching that pattern to fill a demo dataset with plausible-looking numbers.
- Understanding an unfamiliar regex. You inherited a regex from another engineer and aren't sure what it actually matches. Generating example strings from it is often faster than mentally tracing the pattern.
Examples
Match a simple pattern
Input
[a-z]{3}-\d{2}Output
wqz-08 kmx-41 …
About the Generate a String from Regex tool
Generate a String from Regex does its work locally, right in the browser. Produce random strings that match a regular expression. There is no upload step, no queue and no account, and your data never travels over the network.
It belongs to the String Tools collection on EditSafely, a set of 159 small, focused String utilities that share the same instant, private workspace.
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.
Running locally also makes the tool fast and dependable: results appear as you type or drop a file, there is no server outage that can take it down mid-task, and confidential data can be processed without a second thought.
Frequently asked questions
Is Generate a String from Regex free to use?
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?
Everything happens locally. Your browser downloads the tool's code once, then does all the processing itself; nothing you enter is transmitted, stored or logged. You can even go offline after the page loads and it will still work.
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?
No. The tool works in any modern browser on desktop, tablet or phone. There is no account to create, no extension to add and no software to install.
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.