Regex Tester & Debugger
What is a Regex Tester?
Regular expressions (regex or regexp) are patterns used to match and manipulate text. They're supported natively in virtually every programming language and are essential for text processing, validation, searching, and transformation. A regex like \b\w+@\w+\.\w+\b matches email-like strings, while ^\d{4}-\d{2}-\d{2}$ matches ISO date formats. This tool lets you test regex patterns against text in real time, highlighting all matches and showing capture group contents — helping you build and debug complex patterns without writing code.
How to Use the Regex Tester
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Enter your regular expression in the pattern field (without delimiters).
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Set flags as needed: g (global — find all matches), i (case-insensitive), m (multiline — ^ and $ match line start/end).
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Type or paste the test string in the text area.
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All matches are highlighted in the text instantly.
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Capture groups are shown in the results panel below with their index and content.
This regex tester uses JavaScript's built-in RegExp engine and runs entirely in your browser — no data is sent to any server. Highlights all matches, shows capture groups, and supports all standard JavaScript regex flags (g, i, m, s, u). Useful for form validation patterns, text processing scripts, and learning regex syntax.
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