Regex Tester

A regular expression (regex) tester is a developer tool that allows you to write, test, and debug regular expressions in real time. Regular expressions are powerful pattern-matching sequences used in virtually every programming language for text searching, validation, extraction, and replacement operations.

Our free online regex tester lets you enter a pattern and a test string, then instantly see all matches highlighted in the text along with detailed information about each match including its position and capture groups. The tool supports all standard JavaScript regex flags: global (g), case-insensitive (i), multiline (m), and dotAll (s).

Whether you are validating email addresses, parsing log files, extracting data from text, or building search functionality, this tool helps you quickly iterate on regex patterns without writing any code. All processing happens in your browser, so your test data never leaves your device.

1. Enter your regex pattern — Type your regular expression in the pattern field. Do not include the surrounding slashes.
2. Set flags — Check the flags you need: g (global) for all matches, i (case-insensitive), m (multiline), or s (dotAll).
3. Enter test text — Paste or type the text you want to test the regex against.
4. View results — Matches are highlighted in the text and detailed match information is displayed below, including capture group values.
5. Copy matches — Click Copy Matches to copy the detailed match information to your clipboard.