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Regex Builder

Free tool for testing regular expressions and highlighting matches in your regex.

//g

Found 0 matches.

Cheatsheet

RegexExplanation
.any character except newline
\w\d\sword, digit, whitespace
\W\D\Snot 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\Bword, not-word boundary
\.\*\\ escaped special characters
\t\n\rtab, linefeed, carriage return
(abc)capture group
\1backreference 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|cdmatch ab or cd

What is a regex builder?

A regex builder is a tool designed to help you create regular expressions (regex). Our regex builder simplifies the process by providing a user-friendly interface for testing, constructing, and managing complex regular expressions.

FAQ

Regular expressions are sequences of characters that define search patterns, mainly for use in pattern matching with strings. They're fundamental for tasks such as form validation, search and replace functions, data scraping, and text processing.


Regex uses various constructs, such as character classes, quantifiers, and literals, to match specific patterns within text. A regex generator can help create these patterns more efficiently.

A regular expression can be used in various applications. It's essential for handling and manipulating string data. Complex regex is particularly useful for form validation, search and replace functions, data scraping, and text processing, as it allows for more sophisticated pattern matching and text manipulation.


You can use regex to validate email addresses, extract data from HTML, or find and replace specific text patterns within large datasets. Regex constructs accept various patterns, making them versatile for different use cases.

Character classes are a way to match any one of a set of characters in regex. For example, the character class [a-z] matches any lowercase letter from a to z.


You can also use multiple character classes together, such as [a-zA-Z0-9_], which matches any letter, digit, or underscore.

You can test your regular expression directly within the regex builder by inputting your pattern and sample text. The tool provides instant feedback by highlighting matches.
To negate a character class, use [^...], like [^a-zA-Z] to match any character that is not a letter. This negation technique is useful for defining multiple character classes negated in a pattern.
A word character (or character word) is any alphanumeric character plus the underscore (_). It's often represented by the shorthand w in regex.
Regex constructs are the fundamental building blocks of a regex sequence. Understanding regex syntax and how regex elements form patterns is crucial. Regex elements forming these constructs, such as character classes, quantifiers, and capture groups, combine to create powerful regex patterns, enabling effective regex construction.

A regex builder helps create regex patterns for various programming languages using standard syntax. This exact builder is based on a JavaScript implementation, and that’s currently the only flavor available in this tool.


A note ts regex builder is specifically designed for TypeScript. It ensures compatibility with TypeScript's syntax and features, making it easier for TypeScript developers to build and test regex patterns.

To specify that a pattern repeats an exact number of times, use {n}. For instance, \d{4} matches exactly four-digit characters.


To match a whitespace character, use \s, which includes spaces, tabs, and newlines.