| Regex | Explanation |
|---|---|
. | any character except newline |
\w\d\s | word, digit, whitespace |
\W\D\S | not word, digit, whitespace |
[abc] | any of a, b, or c |
[^abc] | not a, b, or c |
[a-g] | character between a & g |
^abc$ | start / end of the string |
\b\B | word, not-word boundary |
\[\*\] | escaped special characters |
\t\n\r | tab, linefeed, carriage return |
(abc) | capture group |
\1 | backreference to group #1 |
(?:abc) | non-capturing group |
(?=abc) | positive lookahead |
(?!abc) | negative lookahead |
a*a+a? | 0 or more, 1 or more, 0 or 1 |
a{5}a{2,} | exactly five, two or more |
a{1,3} | between one & three |
a+?a{2,}? | match as few as possible |
ab|cd | match ab or cd |
Regex Builder is a free online tool for building, testing, and debugging regular expressions with real-time matching and visual feedback. Regular expressions (regex) are powerful pattern-matching sequences used in programming, text processing, and data validation to search, match, and manipulate strings.
The tool provides a live testing environment where you can write a regex pattern and instantly see all matches highlighted in your test string. It includes a comprehensive cheatsheet covering character classes, quantifiers, anchors, groups, and lookaheads to help you construct the right pattern quickly.
Whether you are a developer writing input validation, a data analyst extracting patterns from text, or a student learning regex syntax, this tool provides instant visual feedback and helpful references. All processing runs locally in your browser, so your test data remains completely private.
Type your regular expression pattern into the pattern input field. Set flags like global (g), case-insensitive (i), or multiline (m) as needed.
Enter or paste the text you want to test your pattern against. This can be any string, paragraph, or data you want to match.
Matches are highlighted instantly as you type. You can see all matched groups, capture groups, and their positions in the test string.
Use the cheatsheet to refine your pattern. Once your regex works correctly, copy the pattern for use in your code or application.
See matches highlighted instantly as you type your regex pattern, with no need to click a button
Built-in reference covering character classes, quantifiers, anchors, groups, lookaheads, and more
Toggle common regex flags including global (g), case-insensitive (i), multiline (m), and others
All pattern matching happens in your browser. Your test data never leaves your device
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