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Regex Tester
Build and validate regular expressions with live syntax highlighting for matches and detailed capture group listings. Runs 100% locally.
Regex Configuration
//
Enter pattern and flags (e.g. g for global, i for case-insensitive, m for multi-line).
Results
0 matches
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Frequently Asked Questions
Everything you need to know about processing files securely in your browser
What are regular expressions (Regex) used for?
Regular expressions are patterns used to match character combinations in strings. They are extremely powerful for text validation, search-and-replace operations, and parsing log files.
Which Regex engine does this tester use?
This tool uses your browser's native JavaScript RegExp engine. It supports modern ECMAScript regex features like lookbehind assertions, named capture groups, and Unicode properties.
How do Regex flags like g, i, m, and u work?
Flags modify regex search behavior. g (global) finds all matches rather than stopping at the first; i makes the search case-insensitive; m enables multi-line matching (making ^ and $ match start/end of lines); and u enables full Unicode support.
Are my regex tests or sample texts sent to a server?
No. All pattern matching and text replacement happen in real-time on your computer. Your test inputs and regular expressions remain fully private and offline.