Regex Tester & Debugger
Test regular expressions against sample text with live matching, capture groups, and flags.
About Regex Tester & Debugger
The Regex Tester and Debugger is an interactive developer tool for testing Regular Expressions against sample text with live matching and capture group inspection. Regular expressions are powerful for pattern matching and text extraction, but crafting them can be notoriously tricky. This tool provides real-time match highlighting, group capture breakdown, and modifier flag toggles (global, case-insensitive, multiline), helping engineers debug and refine regex patterns quickly and accurately.
Build and debug regular expressions with real-time match highlighting, group capture inspection, and flag toggles.
How to Use Regex Tester & Debugger
- Enter your Regular Expression pattern into the pattern input box.
- Toggle desired regex flags (g, i, m, s).
- Paste your sample test string into the target text area.
- Inspect highlighted matches and captured groups in real time.
- Refine your pattern until all test cases match correctly.
Common Use Cases
- Validating user input patterns such as email addresses, phone numbers, and postal codes.
- Extracting specific data points from server log files and raw text dumps.
- Debugging complex regular expressions before integrating them into production code.
Frequently Asked Questions
- What regex engine is used?
- Standard JavaScript ECMAScript regular expression engine is utilized.
- Are capture groups displayed?
- Yes, captured groups and match indices are displayed clearly.
- Does it support case-insensitive matching?
- Yes, you can toggle the "i" flag for case-insensitive evaluation.
- Is testing performed locally?
- Yes, regex evaluation runs entirely in your browser.
Related Developer Tools Tools
- JSON Formatter — Format, validate, beautify, and minify JSON data with instant syntax error detection and indentation controls.
- Case Converter — Transform text into UPPERCASE, lowercase, Title Case, camelCase, PascalCase, snake_case, and kebab-case.
- Text Diff Checker — Compare two text blocks or code snippets side-by-side to highlight line additions, deletions, and differences.
- Meta Tag Generator — Generate HTML meta tags, OpenGraph social sharing headers, and Twitter card tags for search engine optimization.