Free tool
DeveloperRegex Tester
Test regular expressions against sample text instantly. See match counts and capture groups before you paste the pattern into production code.
Runs in your browser — your data stays on your device
Free toolA broken regex wastes more time than almost any other one-liner in JavaScript or PHP. This free regex tester lets students and frontend developers validate a pattern against sample text—including API response snippets—without installing software. You write the expression, pick flags, and read the matches in plain language so coding practice stays focused on the pattern, not the toolchain.
How to use the Regex Tester
- 1
Enter your regular expression pattern and optional flags such as g, i, or m.
- 2
Paste the sample text you want to test against.
- 3
Read the match count and match list, then refine the pattern until it behaves as you expect.
Why we teach regex with live samples
In class we see the same traps every week: forgotten escape characters, greedy quantifiers that swallow too much, and flags students never flip. Testing against realistic text—emails in a paragraph, digits in an order ID, path segments in an API log—builds judgment faster than memorising token charts alone.
Regex tester with examples
Tap Email, Digits, or Path to load classroom-ready samples. Compare how a global case-insensitive email pattern finds two addresses, then tighten the pattern until false positives disappear.
Guides and next steps
Privacy note
Regex testing runs entirely in your browser. We do not upload your patterns or sample text.
Frequently asked questions
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