Free online regex tester — test regular expressions, highlight matches, browse capture groups. No registration.
RegEx Visualizer is a browser-based tool for testing and visualizing regular expressions. Enter a pattern and test text — the tool instantly shows all matches with highlighting and listed capture groups. Supports flags g, i, m, s, u. Everything runs locally in the browser — no data leaves your device.
Enter the regular expression in the pattern field — JavaScript RegExp syntax is used natively. Select flags: g (global), i (case-insensitive), m (multiline), s (dotAll — dot matches newlines), u (Unicode). Paste test text — matches appear instantly with yellow highlighting. The match list below shows index, text, and groups for each hit.
The tool fully supports named (?<name>...) and unnamed capture groups — each group is shown in a results table column. Match highlighting works live with a 300ms debounce for smooth performance even with large texts. Results can be copied to the clipboard or downloaded as a TXT file with all matches and their positions.
All processing happens client-side using the native JavaScript RegExp engine — no data is sent to a server. This makes it safe for testing regex on sensitive data, server logs or production code. itcoders.pl RegEx Visualizer is fully free, requires no registration and works in any modern browser.
The tool uses the native JavaScript RegExp engine. Enter the pattern without slashes — e.g. \d+ instead of /\d+/. Select flags with the buttons. Syntax follows ECMAScript standard, including named groups (?<name>...), lookahead/lookbehind and Unicode classes.
Yes — five flags are available: g (global — all matches), i (case-insensitive), m (multiline — ^ and $ match line boundaries), s (dotAll — dot also matches newline characters) and u (Unicode mode).
Yes — the tool uses a 300ms debounce, so it runs smoothly even on texts of tens of thousands of characters. For very large match counts, the results table has a fixed scrollable height.
No — all processing happens locally in the browser using the JavaScript RegExp engine. No data leaves your device, which is critical when testing regex on sensitive data.