Regex Tester

Regular expressions are famously write-only: easy to produce, hard to trust. The gap between "I think this pattern matches emails" and "it actually does, on my data" is exactly what a tester closes. Type a pattern, paste your real text, and every match lights up instantly — no guessing, no console.log loops, no deploying to find out.

Three things make this tester genuinely useful for debugging. Matches are highlighted inline in your test string, so you see not just that the pattern matched, but precisely which characters it consumed — the fastest way to spot a greedy quantifier eating more than intended. Capture groups are listed per match below, so extraction patterns can be verified before they reach your code. And invalid patterns show the JavaScript engine's own error message, which names the actual problem ("Unterminated group") instead of failing silently.

The three most-used flags are one click each: g (find all matches, not just the first), i (ignore case) and m (multiline, so ^ and $ match line boundaries). The tester uses your browser's native JavaScript regex engine — meaning what matches here matches identically in your Node.js or frontend code, with no dialect surprises. A sample email pattern is preloaded so you can see it working immediately.