Free Regex Tester
Test regular expressions with live match highlighting, capture groups and a handy pattern cheat-sheet. Free, instant, no signup.
How to Use the Regex Tester in 3 Steps
- Enter your regular expression in the pattern field (JavaScript flavor) and pick flags like g, i or m.
- Type or paste your test text — every match is highlighted live as you type.
- Inspect capture groups below and use the cheatsheet to fix or refine your pattern.
Frequently Asked Questions
Is it free?
Yes, completely free with no limits and no cost. Test as many regular expressions against as much sample text as you want, as often as you want. No credits, no premium tier, no signup — the full tester including the cheatsheet is free for everyone.
Do I need to sign up?
No signup needed — ever. Just open the page and start testing regular expressions immediately: no account to create, no email address required, no trial to expire. Everything runs locally in your browser the moment the page loads, with zero setup.
Is my data/code private?
Yes, 100% private. Your patterns and test text are processed entirely in your browser using JavaScript — nothing is sent to any server, nothing is logged, and nothing is stored anywhere. Safe for testing regex against proprietary code, server logs or sensitive customer data.
Which regex flavor does it use?
The tester uses the JavaScript (ECMAScript) regex flavor — the same engine that runs in browsers and Node.js. Most common syntax like \d, \w, character classes, quantifiers, groups and lookaheads works identically in Python, Java and other languages, but exotic features may differ slightly.
What do the flags (g, i, m) do?
The g flag finds all matches instead of stopping at the first. The i flag makes matching case-insensitive, so 'a' matches 'A'. The m flag makes ^ and $ match the start and end of each line in multi-line text, not just the whole string. Combine them — like gim — for powerful searches.
Why is my regex showing an error?
Usually it's an unclosed bracket, parenthesis or character class — like (abc or [0-9. Invalid escape sequences and stray quantifiers (* or + with nothing before them) also trigger errors. The tester highlights the problem and shows the browser's exact error message so you can fix it fast.
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