Regex Tester & Debugger

Regular expressions are the Swiss Army knife of text processing — and the easiest way to ship a silent bug. A greedy quantifier grabs too much, a missing backslash breaks a character class, a wrong flag flips the meaning of the dot. The only reliable way to get a pattern right is to test it against real text before it ever touches production. That is exactly what this tester is for. Type a pattern such as \b\w+@\w+\.\w+\b into the pattern field, choose flags like g (global) and i (ignore case), then paste the text you want to search. The tool highlights every match and, when your pattern uses capturing groups, lists each group's contents so you can confirm the extraction works exactly as intended. Want to validate an email, pull URLs out of a block of copy, strip HTML tags, or split a log line into fields? Write the pattern, watch the highlights, adjust, repeat — the feedback loop is instant. Because the engine is the browser's built-in RegExp, what you see here is what you get in your JavaScript, TypeScript, or Node.js code. There is no "works in the tester but not in my app" surprise. And because it is client-side, the text you paste — which might be customer data, private logs, or unreleased copy — never leaves the visitor's device. A few practical tips. Use ^ and $ to anchor when you mean "the whole string", not "somewhere inside it". Remember that . does not match newlines unless you add the s flag. Escape special characters ( . * + ? ^ $ { } [ ] ( ) | / ) with a backslash when you mean the literal character. When a pattern gets complicated, break it into named groups so the output list is self-documenting. This page is part of a larger toolbox of free, privacy-first utilities. Pair the tester with the JSON formatter when you are extracting values from API responses, or with the text transforms when you need to clean the captured text afterward. Expand this copy with tutorials and worked examples for your niche before applying for AdSense.