Live highlighted matches, capture groups, replace preview, and step-by-step pattern explanations. 50+ pre-built patterns, catastrophic backtracking detection, 100% offline.
A focused popup with live evaluation, the kind of tooling senior engineers wish they had installed three years ago.
Type a pattern, see matches light up character-by-character in your test text. JS regex engine, all standard flags (g, i, m, s, u, y).
Inspect every capture group in a clean table. Reference them with $1, $2 or $<name> in replace mode.
Type a replacement string and see the transformed output update on every keystroke.
The AST walker breaks any pattern into a tree of plain-English nodes. Hover any token, see what it does and why.
Email, URL, IPv4/v6, UUID, ISO date, semver, JWT, hex color, credit card, AWS keys, GitHub tokens, and more. One click to load.
The performance profiler runs your pattern in a sandboxed Web Worker with a 1-second timeout. Catch ReDoS bugs before they ship.
Bookmark patterns you'll use again. Free saves 3, Pro saves unlimited with tags, notes, and search.
Last 5 tests on free, last 100 on Pro. Restored every time you reopen the popup.
Patterns and test text never leave your browser. License check sends only a random device ID. Verify in your network tab.
Paste any regex into the pattern field. Toggle flags. The popup compiles on every keystroke and tells you immediately if it's invalid.
Every match in your test text is highlighted instantly. Capture groups appear in a table. Match counts update on every keystroke.
Bookmark patterns you'll use again, or load from the 50+ pattern library so you stop rewriting the same email regex from memory.
No signup, no email, no trial countdown. Free works forever. Pro unlocks the explainer, the full library, the profiler, and unlimited saves.
For occasional regex work.
Cancel anytime. 30-day refund.
Pays for itself in 4 months.
Yes. Live matching, replace, the cheatsheet, the AST explainer, and the backtracking profiler all run 100% locally. Only license verification and growth pings need the network, and both gracefully degrade.
JavaScript regex (ECMAScript 2018+) for live evaluation. The cheatsheet and explainer note where syntax differs from PCRE / Python / Go so you can spot portability issues.
No. Patterns and test strings are processed locally in your browser. The license check sends only a random device ID, no content.
Same Pro features, different commitment. Lifetime pays for itself in four months and is the best deal if you regex more than once a week.
Yes, within 30 days of purchase. Email support@peakproductivity.online and we'll refund without questions.
Tested cleanly up to 1MB. Beyond that, the live highlighter switches to debounced mode to keep the popup responsive.
Regex Tester Pro