Regex Tester | Tools Hub

Expression & Test

Write your pattern and test against string data.

Test String 0 matches

Live Match Preview

Capture Groups

No capture groups in matches

Critical Engineering Disclaimer

Environment Differences.

JS Mode: Uses your browser's native engine. Fast, but lacks advanced features like lookbehinds on older browsers.
Python Mode: Uses Pyodide (WASM) to run the real CPython `re` module in your browser. This requires downloading ~10MB of data.
Flags: Both engines now behave identically. Without 'g' flag, only the first match is found. With 'g' flag, all matches are found. Common flags: i (case-insensitive), m (multiline), s (dotall), x (verbose, Py only), a (ASCII, Py only).
JS-only flags: u, y, d, v are supported in JS mode only.