Regex Tester & Matcher (Private & Secure)
Test regular expressions in real-time with regex flag controls, group matches, and string replacement preview.
How to use
- Enter your regular expression pattern and flags.
- Paste test string into the text area.
- Inspect each match, its index range, and capture groups ($1, $2...) in real time.
Technical Considerations
- Supports lookbehind assertions (native JS RegExp).
- There is no backtracking timeout, so patterns like (a+)+$ can freeze the tab.
100% Client-Side Privacy: This tool executes entirely within your browser's runtime environment. No payloads, tokens, or inputs are transmitted to external servers.