Regular expression tester with syntax highlighting, explanation, cheat sheet for PHP/PCRE, Python, GO, JavaScript, Java, C#/.NET, Rust.

Test and generate regular expressions in real-time. Free online regex tool for developers with syntax highlighting, pre-built examples, and instant match results.

Test and debug your regular expressions online in real-time. Our free regex tool highlights matches, shows capture groups, and includes a library of common patterns and a handy cheatsheet.

RegExr is an online tool to learn, build, & test Regular Expressions (RegEx / RegExp).

Mar 17, 2026 · Regular expression syntax cheat sheet This page provides an overall cheat sheet of all the capabilities of RegExp syntax by aggregating the content of the articles in the RegExp guide. If …

Dec 22, 2025 · A regular expression (regex) is a sequence of characters that defines a search pattern. It is mainly used for pattern matching in strings, such as finding, replacing, or validating text.

A quick reference for regular expressions (regex), including symbols, ranges, grouping, assertions and some sa

A tool to generate simple regular expressions from sample text. Enable less experienced developers to create regex smoothly.

Nov 12, 2009 · I need a regex which will allow only A-Z, a-z, 0-9, the _ character, and dot (.) in the input. I tried: [A-Za-z0-9_.] But, it did not work. How can I fix it?

Jan 5, 2025 · Regex cheat sheet: character classes, anchors, quantifiers, groups, lookarounds, and flags, with a per-engine table for JS, Python, PHP, Go, and more.