See exactly what your regex matches
Regular expressions are hard to debug in your head. This tester runs your JavaScript regex against a test string and highlights every match in place, counts them, and lists each match's index and capture groups. Toggle flags like global, case-insensitive and multiline with a click, and get instant, readable feedback the moment your pattern changes.
Build, replace and reuse
Start from a preset for common patterns — email, URL, IPv4, hex colour, phone or date — then adapt it to your data. The replace panel previews the result of a substitution with $1, $2 group references, so you can craft find-and-replace rules with confidence. A quick cheatsheet keeps the syntax handy, and everything runs in your browser so your test data stays private.
Features
- 01
- Live match highlighting as you type
- 02
- All flags: g, i, m, s, u, y
- 03
- Capture-group and match-index breakdown
- 04
- Replace preview with $1 group substitution
- 05
- Preset patterns: email, URL, IPv4, hex, phone
- 06
- Built-in cheatsheet, runs 100% locally
