Test regular expressions safely
The Regex Tester compiles a regular expression against your sample text and highlights every match, group and capture in real time. Flags (global, case-insensitive, multiline and friends) are one click each, and replacement mode previews substitutions with backreferences before you commit them anywhere.
Regular expressions are write-only by reputation: correct in your head, surprising in production. Testing against real sample data — including the cases you expect to fail — before embedding a pattern in code prevents both false matches and catastrophic misses. Seeing groups colour-coded makes complex patterns comprehensible at a glance.
Everything is compiled and matched locally by your browser's own regex engine, so the behaviour you see is exactly what your JavaScript will do. Patterns are never sent to a server, and sample data stays on your device.
Like every Piclizer tool, this one runs entirely in your browser — your files stay on your device.