Regex Tester
Test regular expressions.
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How to Use the Advanced Regex Tester
Write or paste your regular expression in the pattern field, or load a common pre-built pattern from the dropdown.
Add optional regex flags like global (g), case-insensitive (i), or multiline (m) in the flags input field.
Enter your test string below. Click "Test Regex" to immediately find all matches, capture groups, and index positions.
Features & Benefits
100% Privacy Preserved
All regular expression evaluations occur entirely within your browser. Your regex patterns and sensitive test strings are never uploaded to our servers.
Instant Feedback
Leveraging native JavaScript RegExp capabilities, the tool processes complex text matches and capture groups instantaneously.
Pre-built Pattern Library
Not a regex expert? Use our built-in library to instantly validate common data types like email addresses, phone numbers, URLs, and IPv4 addresses.
Deep Inspection
Not just simple true/false validation—our advanced engine extracts every exact match, its string index position, and every individual capture group.
Frequently Asked Questions
Which Regex flavor does this tool use?
Because this tool runs in your browser, it utilizes the standard JavaScript (ECMAScript) Regular Expression engine. This is highly compatible with PCRE but may lack a few advanced features found only in Python or PHP.
What are capture groups?
Capture groups are parts of a pattern enclosed in parentheses ( ). They allow you to extract specific sub-strings from a larger match. Our tool automatically displays the contents of all matching capture groups.
What do the flags mean?
Flags change how the search operates. g (global) finds all matches instead of stopping at the first. i makes the search case-insensitive. m makes the start (^) and end ($) anchors match the start/end of lines instead of the whole string.
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