Regular Expression Language - Quick Reference

MSDN documentation about Regex.

Regular Expressions

MDN chapter about JavaScript regular expressions.

Perl Regular Expression Syntax

Boost documentation.

Perl 6

Regexes in Perl 6.

PCRE

Concatenated PCRE man pages.

ECMAScript 6

New Regexes in ECMAScript 6.

regex header in C++

<regex> in C++

class Pattern in Java

Java 7 docs.

class Regex in Scala

Scala Regex.

Python re module

Regular Expressions Python module tutorial.

Regular Expressions in Perl

Introduction and Reference Links.

Debuggex

Online visual Regex tester.

ExtendsClass

Online visual Regex tester.

Nodexr

Online node-based Regex editor.

Regexr

Website for interactive Regex prototyping with syntax highlighting (by @gskinner).

Regex101

Online Regex tester, debugger with highlighting.

Rubular

Ruby-based regular expression editor and tester.

Rex V

AJAX Regular EXpression eValuator.

RegViz

Tool for debugging JavaScript regular expressions in a visual way.

Regulex

JavaScript Regular Expression Visualizer.

PyRegex

Online Regex tester to check validity of Regex in the Python language Regex subset.

pythex

Quick way to test your Python regular expressions.

Regexper

Regex visualizer for JavaScript using railroad diagrams.

HiFi Regex Tester

Live JavaScript Regular Expression Tester.

Regex Hero

.NET online Regex tester.

Regex Storm

.NET Regex tester with highlighting and detailed results output.

RegEx to Strings

JavaScript library and online tool to generate strings that a regular expression would match.

RegexPal

JavaScript + PCRE online tester.

RegexTester

Regular Expression Tester with highlighting for Javascript and PCRE.

Free Formatter

Free online Regex tester.

Regex Tester - Golang

A secure regular expression tester. built using Go

PHP Live Regex

PHP specific regular expression tester with live evaluation and code generation for all PHP's regex functions.

Txt2Re

Generate Regular expressions based on a string

Regex Generator++

Automatic Generation of Text Extraction Patterns from Examples

regexgen

Generates regular expressions that match a set of strings.

RegexGenerator

A tool for generating regular expressions for text extraction (by @MaLeLabTs)

Gamon's numberic range generator

Regex Numeric Range Generator, when you need to match an integer range.

rgxg

Command line tool to generate Regex

Strings to RegEx

JavaScript library and online tool to generate a regular expression that matches strings.

Regex Guide

Plain Text to Regex Generator.

grex

A command-line tool and library for generating regular expressions from user-provided test cases.

AutoRegex

English <-> Regex from an AI.

SafeRegex

A command-line tool for testing regular expressions for ReDoS vulnerabilities.

Wikipedia

Entry on regular expressions.

Learn Regex The Hard Way

In-progress book that quickly teaches you regular expressions.

Regular Expression Matching Can Be Simple And Fast

Basic concept of how Regex parsing works.

Regular-Expressions.info

Informative website for learning regular expressions.

RexEgg

A regular expressions tutorial that goes deep into advanced features.

Try Regex

Try Regex is an interactive regular expressions tutorial.

Udemy

A Basic Introduction To Using Regular Expressions In Programming.

Codecademy

How to use of regular expression.

Regex golf

Regex golf with Peter Norvig.

Python Regular Expressions

A good introduction to Python Regular Expressions from Google.

/Reg(exp){2}lained/: Demystifying Regular Expressions

Fluent 2012 talk reviewing and visualizing basic and intermediate Regular Expressions.

Regular Expressions - Everything you should know

PDF Series.

The Java Tutorials

Regex Syntax Summary

How Regexes work

Learn Regular Expressions for Beginners

Java Regex Tutorial

Javascript.info - Regular expressions

Regular expressions section in The Modern JavaScript Tutorial

Useful Regexes

Teach Yourself Regular Expressions

Interactive Regex Tutorial

Learn Regex step by step, from zero to advanced.

Tre

Free and portable approximate Regex matching library.

Go-Restructure

Match regular expressions into struct fields in Go (by @alexflint). js C#

js-regex

Chainable API for constructing Regexes.

VerbalExpressions

VerbalExpressions is a cross-language library that helps to construct difficult regular expressions.

Super Expressive

Super Expressive is a JavaScript library that allows you to build regular expressions in natural language.

XRegExp

JavaScript Regex library.

RE2

RE2 is a fast, safe, thread-friendly alternative to backtracking regular expression engines like those used in PCRE, Perl, and Python. It is a C++ library.

Hyperscan

High-performance multiple Regex matching library.

RegexLib

Regular Expression Library (5000+ indexed expressions).

Regexhub

Useful Regex Patterns.

RGXP.RU

Regular Expression Patterns (+testing)

RegexTranslator

A web app to decode Regex into plain English. You can edit it and translate back.

Explain.pl

Explain Regular Expressions.

HackerRank Regex Challenges

Regex challenges with varying levels of difficulty.

Redoku

Little Regex Sudoku/Crossword thing (by @padolsey).

Regex Tuesday - Challenges

Challenge list about Regex.

Regex Crossword

A crossword puzzle game using regular expressions.

RegexOne

Learn regular expressions with simple, interactive examples.

Regex Exercises

Regexp exercises.

Regular Expression Crossword Puzzle

A crossword puzzle with a neat web interface.

5 Techniques to Improve Regex Performance

Craft your own powerful, yet efficient regex.

The Bad, the Better, and the Best

How a few characters can make a difference in performance.

The Greatest Regex Trick Ever

So you're doubtful at the mention of a "best Regex trick"?

Treat regular expressions as code, not magic

If you don’t write them carefully, you can end up with an unmaintainable monstrosity.

Demystifying The Regular Expression That Checks If A Number Is Prime

How a regular expression can check if a number is prime.

Regex Tree: a regular expressions processor

The thirty minute regex tutorial

Regular Expressions in 30 Minutes.

Regular Expression Matching Can Be Simple And Fast

On non-backtracking engines. A follow up includes comparisons of RE2 and PCRE performance.

Regular Expressions in a post ES6 World

Regular expression (regex) performance: The fundamental guide

The New ‘Absent Operator’ in Ruby’s Regular Expressions

Optimizing regexes in Java

Use Regex to Test Password Strength in JavaScript

Java 101

Regular Expressions in Java.

Most Crazy Regexes

Stack Overflow

Regex Humor

Regex jokes and cartoons.

The true power of regular expressions

On code, early neural networks, and once discredited AI pioneers

A short history of regexes

Patterns, Automata, and Regular Expressions

Al Aho and Jeff Ullman (1992) (chapter 10 of Foundations of Computer Science)

Beginning Regular Expressions

Andrew Watt (2005)

Mastering Regular Expressions

Jeffrey E.F. Friedl (2006)

Regular Expression Pocket Reference

Tony Stubblebine (2007)

Introducing Regular Expressions

Michael Fitzgerald (2012)

Regular Expressions Cookbook

Jan Goyvaerts & Steven Levithan (2012)

Mastering Python Regular Expressions

Felix Lopez & Victor Romero (2014)

JavaScript Regular Expressions

Loiane Groner & Gabriel Manricks (2015)

Regex - the complete tutorial

Python re(gex)?

Sundeep Agarwal (2020)

Benchmark of Regex Libraries

Java regular expression library benchmarks – 2015

Languages Regex Benchmark

It's just a simple Regex benchmark of different programming languages.

Performance comparison of regular expression engines

Regex Performance

Performance comparison of regular expression engines.

Regular Expressions Cheat Sheet

Regex Cheat Sheet

MIT Cheat Sheet

Java Cheat Sheet

JavaScript Cheat Sheet

RegexLearn Cheat Sheet