Regex Tester
Test regular expressions with real-time matching and group extraction.
Quick insert:
Enter a test string to see matches
Regex Flags
g
Global - Find all matches instead of stopping at the first.
i
Case-insensitive - Ignore case when matching.
m
Multiline - ^ and $ match line boundaries.
s
Dotall - Dot (.) matches newline characters.
u
Unicode - Enable full Unicode support.
All processing happens locally in your browser. No data is sent to any server.
Technical Specification
Regular Expression Testing & Pattern Matching Engine
Overview
The ToolsForges Regex Tester provides a real-time regular expression testing environment where developers can write, test, and debug regex patterns against sample text inputs with instant visual feedback. Enter a regex pattern, select flags, and input test strings to see highlighted matches, capture groups, and match positions rendered in real time as you type.
Feature Specifications
- Real-Time Match HighlightingSee matches highlighted in the test string as you type the regex pattern, with color-coded capture groups showing exactly which portions of the input satisfy each part of the expression.
- Capture Group DisplayView all captured groups in a structured table showing group index, matched text, and position, enabling precise verification of complex pattern extraction logic.
- Regex Flag ControlsToggle global, case-insensitive, multiline, and dotAll flags with checkboxes, seeing how each flag modification affects match results in real time.
- Pattern ExplanationReceive a human-readable explanation of the regex pattern structure, breaking down each token, quantifier, and assertion for educational and debugging purposes.
Architecture
The tester uses React useState for pattern, flags, and test input. The regex engine compiles the pattern using the JavaScript RegExp constructor and applies it to the test string with matchAll for global matching. Results render with highlighted spans and a capture group table.
Frequently Asked Questions
Which regex flavor does this tool use?
The tool uses the JavaScript regex engine, which supports the ECMAScript standard including ES2015+ features like named capture groups, Unicode property escapes, and lookbehind assertions.
Can I test regex patterns for Python or other languages?
The JavaScript regex syntax is similar to PCRE used by Python and many other languages. Most basic to intermediate patterns transfer directly, but advanced features may have syntax differences.
Is there a pattern length limit?
The tool handles patterns of practical length without restriction. Very long or complex patterns may experience brief compilation delays depending on the regex engine's backtracking behavior.
Is my test data stored?
No. All regex patterns, test strings, and match results are processed entirely within your browser. No pattern-matching logic or test data is transmitted to external servers.