Regex Tester
DeveloperTest regular expressions with real-time matching and highlighting. Debug and validate regex patterns with instant feedback.
Match Results
What is This Tool?
A regex tester lets you write, test, and debug regular expressions against sample text in real time. See matches highlighted instantly, capture groups extracted, and get detailed explanations of your regex pattern — supporting JavaScript, Python, and other regex flavors.
Regular expressions are a powerful pattern-matching language used in virtually every programming language. Despite their power, regex syntax is notoriously cryptic. This tool provides instant visual feedback, match details, and pattern explanations to make regex development faster and less error-prone.
Common Use Cases
Pattern Development
Build and test regex patterns interactively with instant match highlighting before using them in code.
Data Validation
Create and test validation patterns for emails, phone numbers, URLs, dates, and other structured data formats.
Text Extraction
Develop capture group patterns to extract specific data from logs, HTML, CSV, and other text formats.
Search & Replace
Test find-and-replace patterns with backreferences for bulk text transformation and code refactoring.
Frequently Asked Questions
Which regex flavor is used?
JavaScript regex by default (same as browsers and Node.js). Differences from PCRE/Python: no lookbehind in older engines, no atomic groups.
Are regex flags supported?
Yes. Global (g), case-insensitive (i), multiline (m), dotAll (s), and unicode (u) flags are all supported.
What are capture groups?
Parentheses () create capture groups that extract matched substrings. Named groups (?<name>...) make extractions more readable.