Regular Expression Tester & Studio ProLive Highlighting & AST
Build, test, debug, and replace regular expressions in real-time with visual group inspector and multi-language code generators.
Quick Syntax Cheat Sheet (Click to Insert)
Execution Performance & Match Metrics
Enterprise Regular Expression Studio & Match Inspector
Test expressions against real-world data, inspect capture groups, and export production code across 6 languages.
Real-Time Visual Highlighting
Matches are highlighted reactively as you type with color-coded indices, character ranges, and zero-length loop protections.
Deep Capture Group Inspector
Inspect numbered capture groups (`$1`, `$2`), ranges, and character counts for every match with instant search filtering.
Multi-Language Code Export
Generate production-ready code snippets for JavaScript, TypeScript, Python 3 `re`, Go `regexp`, Java, PHP, and C# .NET.
Frequently Asked Questions
What do the regex flags mean?
g (global: match all occurrences), i (case-insensitive), m (multiline: ^ and $ match line starts/ends), s (dotAll: . matches newlines), and u (unicode support).
How does Substitution / Replace work?
You can replace matches with static text or reference captured groups like $1 and $2 to rearrange string formats in the Replaced Text tab.
Is my test data uploaded to a server?
No! 100% of regular expression execution, matching, and replacement executes client-side in your local browser memory.
Does this tool support large log files?
Yes! You can upload log files and datasets with thousands of lines, and the engine will display live execution benchmark times.
How to Use RegEx Tester
Test regular expressions with real-time matching and capture groups. Follow the quick steps below to operate this tool with maximum speed and complete local privacy.
Step-by-Step Instructions
Simple, actionable steps to use RegEx Tester efficiently.
Enter Regex Pattern
Type your regular expression pattern and select flags (global, case-insensitive, multiline, dotAll, unicode).
Input Test String
Paste your test string or upload log files to test your pattern.
Inspect Matches & Code
View live highlighted matches, capture groups, or export production code for JavaScript, Python, Go, and Java.
How It Works & Capabilities
Technical advantages and operational functions of this tool.
1. In-Memory Input
Files or text inputs are ingested directly into active browser RAM. No temporary files or logs are ever transmitted to any external server.
2. Client-Side Processing
Calculations, transformations, and compilations are performed locally utilizing WebAssembly and modern JavaScript engines for real-time speed.
3. Instant Local Export
Save your results immediately to disk or copy data to clipboard. Outputs maintain complete original quality with zero watermarks.
Frequently Asked Questions
Clear answers about privacy, limitations, and how RegEx Tester functions.