About

Past sponsors

• <img src="https://github.com/antfu.png" width="40" height="40">
• <img src="https://github.com/brc-dd.png" width="40" height="40">
• sponsoring

Regex processors, utilities, and more

• Steven Levithan - regex/graphs/contributors).

Sponsors and backers

• <img src="https://github.com/roboflow.png" width="40" height="40">

Articles

Regex processors, utilities, and more

• *The World's Shortest Regex Compiler?* - dfa) on optimization - Introduction to writing a non-backtracking regex engine (in JavaScript).
• *Regex Legends: The People Behind the Magic* - Influential people behind the technology.

Books

Regex processors, utilities, and more

• *Regular Expressions Cookbook, 2nd Edition* - Regex tutorial with code samples for eight programming languages, 100+ regex recipes for practical problems, and a deep focus on cross-flavor differences.
• *Mastering Regular Expressions, 3rd Edition* - A computer science classic, best for people who already know the basics. Includes good coverage of crafting efficient regexes.
• *Introducing Regular Expressions* - An intro for programmers new to regular expressions that sticks to the basics.

Collections of patterns

ReDoS checkers

• Book: Regular Expressions Cookbook, 2nd Edition - High-quality solutions with detailed explanations.
• Regex DB - Solutions include basic descriptions and examples of matching and non-matching text.

Communities

Regex processors, utilities, and more

• Reddit: r/regex
• Stack Overflow: &lsqb;regex&rsqb;

Grep-like tools

Command line

• Feature comparison of grep-like tools
• ripgrep - Better and faster grep. Recursively searches directories while respecting gitignore rules and skipping hidden/binary files.
• nomino - Rename files uses regexes.

GUI

• Aba Search and Replace - Displays matches as you type.
• PowerGREP - Can search through archives, binary files, PDFs, docs/sheets, emails, etc., via its GUI or the command line.
• PowerRename - Rename files using regexes.

JavaScript regex evolution

Regex processors, utilities, and more

• [*explainer*
• [*explainer*
• [*explainer* - folding for flag i, and code point matching (with impact on quantifiers, character classes, ranges, and built-in sets).
• [*explainer* - tos/run-chromium-with-flags/)].
• Can I use - Up-to-date browser support tables for individual features.
• flag `s` - regexp-lookbehind), named capture, and Unicode properties (via \p{…} and \P{…} which require flag u; see list).
• `matchAll`
• `replaceAll`
• flag `d`
• flag `v` - v-flag)] as an upgrade to flag u, which adds a set of multicharacter "properties of strings" to \p{…}, multicharacter elements within character classes via \p{…} and \q{…|…}, nested character classes, set operators […--…] and […&&…], and different escaping rules within character classes. It also fixes case-insensitive matching for \p and \P within negated [^…].
• regexpu - unicode-properties)).
• Extended mode and comments - Flag x (extended) with insignificant whitespace and line comments (#…), plus inline comments via (?#…).
• modifiers - duplicate-named-capturing-groups) in separate alternation paths, and RegExp.escape.
• Atomic operators - Atomic groups via (?>…) and possessive quantifiers (ex: *+, ++).
• Buffer boundaries - Anchors \A and \z, not affected by flag m.
• \R escape - Outside character classes, \R matches any line terminator.
• Restrict subclassing support in built-ins - Scaled back RegExp subclassing.
• Legacy RegExp features - Standardization of legacy features.
• standard
• *Regexes Got Good: The History And Future Of Regular Expressions In JavaScript*

JavaScript regex libraries

Abstracted regex syntax

• Rexx - A template tag that uses structured syntax with variables and comments.
• Melody - lavi.github.io/melody/book/)] - A language that compiles to regexes.
• compose-regexp.js - regexp](https://github.com/unjs/magic-regexp) [home], Super Expressive [playground].

Alternative regex builders and engines

• Regex+ - A template tag for extended, readable, high-performance JavaScript regexes.
• node-re2 - oniguruma](https://github.com/microsoft/vscode-oniguruma) (Oniguruma).
• Oniguruma-To-ES - Convert Oniguruma patterns to native JavaScript regexes.

Regex processors, utilities, and more

• AST Explorer: RegExp - regexp-ast-viewer/).
• regexp-ast-analysis - ast-analysis/docs/latest/)] - Analyze AST nodes produced by regexpp.
• Regex Colorizer - colorizer/demo/)] - Highlight regex syntax.
• eslint-plugin-regexp - meshi.github.io/eslint-plugin-regexp/)] - ESLint plugin for finding regex mistakes, etc.
• randexp.js - to-strings](https://github.com/wimpyprogrammer/regex-to-strings).
• regexgen - Generate a regex that matches a set of strings.
• regexpp - tree](https://github.com/DmitrySoshnikov/regexp-tree), regjsparser/regjsgen, regexp-simple-parser.
• regex-utils - Check regex equivalence, build regex intersections, and other utilities.
• regex-to-mermaid - Generate Mermaid diagrams to visualize regexes.
• arkregex - RegExp-equivalent constructor with TS types.
• super-regex - Add an execution timeout to regexes.
• regex-partial-match - regex-package](https://github.com/nurulc/incr-regex-package).

Miscellaneous

Regex processors, utilities, and more

• regex101 Regex Quiz - Requires sign-in.
• Regex Crossword - machina/) ($).
• xkcd

Performance

Benchmarking

• rebar - benchmark](https://github.com/mariomka/regex-benchmark).

Crafting efficient regexes

• Runaway Regular Expressions: Catastrophic Backtracking - Exploration and solutions for superlinear backtracking.
• Book: High Performance JavaScript - Chapter 5: Strings and Regular Expressions.
• Book: Mastering Regular Expressions, 3rd Edition - Chapter 6: Crafting an Efficient Expression.
• Performance of Greedy vs. Lazy Regex Quantifiers - Illustrates the mechanics of backtracking.
• Performance of Regular Expressions - On backtracking performance, with detailed examples.

Flavor differences

• ReDoS

ReDoS checkers

• regex.rip - Test a regex for ReDoS vulnerability.
• recheck - labs.github.io/recheck/)] - JavaScript and Scala library for detecting ReDoS vulnerability. Can be used as an ESLint plugin.
• vuln-regex-detector - Perl library for detecting ReDoS vulnerability.

Regex engine optimization

• Regular Expression Matching Can Be Simple And Fast - On non-backtracking engines. A follow up includes comparisons of RE2 and PCRE performance.
• Regular Expression Improvements in .NET 7 - performance-improvements-in-net-5/) - Includes detailed explanations of performance optimizations.

Regex engines

Documentation

• RegExp - US/docs/Web/JavaScript/Reference/Regular_expressions), Guide, Cheatsheet.
• Regular Expressions
• Pattern - summary.html).
• Overview - us/dotnet/standard/base-types/regular-expression-language-quick-reference), API.
• RE
• Syntax
• Syntax
• Grammars - best-practices)).
• Regular Expressions - Flavor: PCRE.
• Regexp - Flavor: Onigmo.
• regexp - Flavor: RE2.
• RE
• Pattern
• Regular Expressions - Flavor: ICU.
• Introduction

Flavor differences

• Tools & Languages
• Named capture
• Comparison of regular expression engines
• Regular Expression Feature Comparisons - features)].

Source code

• V8: Irregexp - Regex engine used by Chrome, Edge, Firefox, etc.
• Java: java.util.regex - JDK standard regexes.
• .NET: System.Text.RegularExpressions - Shared by all .NET languages (C#, VB, etc.).
• Perl - See perlreguts.
• Python: re - regex) - Standard and extended regex libraries.
• JavaScriptCore: RegExp - Regex engine used by Safari.
• ICU - Unicode org's package with full Unicode support.
• Boost.Regex - C++ regex library.
• Hyperscan - Intel's high-performance library, used for DPI.
• Onigmo - Forked from Oniguruma. Used by Ruby 2.0+.
• Oniguruma - C regex library used by Ruby 1.9, TextMate grammars, etc.
• PCRE2 - Popular C regex library used by PHP, R, etc.
• RE2 - Popular C++ regex library used by Go, etc. Non-backtracking engine.
• Rust: regex - Non-backtracking engine.

Syntax-free regex builders

• ChatGPT - Ex: "create a regex that matches X and explain it step by step".
• RegexMagic - Generate regexes using samples and rules.
• Regex Generator - generator)] - Generate simple regexes from a sample text.
• Regex.ai - Mark samples in a text and use AI to generate potential regexes.

Testers

• regex101 - Best free and best web-based tester.
• RegexBuddy - Best tester.
• RegExr - Best open source tester.
• fork
• RegexLearn - Best multilingual tester (JavaScript).
• regexplained - Best tester for presentations (JavaScript).
• PHP Live Regex
• Pythex
• Rubular
• CyrilEx - Java, JavaScript, MySQL, PHP, Python, Ruby.
• Patterns - Bash, Emacs, grep, Java, Oniguruma, PCRE, POSIX BRE, POSIX ERE, Ruby, sed.
• RegexPlanet - Go, Java, JavaScript (Bun, Deno, Node.js), .NET, Perl, PHP, PostgreSQL, Python, Ruby, Rust, Swift, Tcl, XRegExp.
• GNU sed REPL
• pcre2test - Includes regex debugger. Flavor: PCRE.
• rxrx - Includes regex debugger (video intro). Flavor: Perl.
• fancy-regex playground - regex/fancy-regex/tree/main/playground)].
• RegViz
• Regex Storm - storm)].
• Swift Regex - Includes regex debugger, DSL builder.
• RegexPilot - Best Mac-native tester.

Tutorials

Traditional

• Regular-Expressions.info - Covers numerous regex flavors.
• The Modern JavaScript Tutorial: Regular expressions - tutorial/en.javascript.info)] - Guide to using regexes in JavaScript.
• others
• RexEgg - Detailed tutorial with advanced topics.
• learnbyexample - Ebooks on regexes (JavaScript, Python, Ruby) and command line text processing.
• Regular Expressions for Regular Folk - for-regular-folk)] - Visual, example-based ebook for beginners.

Videos

• *Demystifying Regular Expressions* - Great presentation for beginners, by Lea Verou at HolyJS 2017 (1hr 12m).
• *Learn Regular Expressions In 20 Minutes* - Live syntax walkthrough in a regex tester, by Kyle Cook.
• Udemy

With interactive exercises

• RegexLearn - Interactive tutorial and practice problems.
• RegexOne - Interactive tutorial and practice problems.

Visualizers

• Regex Vis - vis)] - Create railroad diagrams, with visual editor. Flavor: JavaScript.
• Regulex - Create railroad diagrams. Flavor: JavaScript.
• Nodexr - Graphical editor with visual hierarchy. Flavor: .NET.
• Regex Nodes - nodes)] - Graphical editor with visual hierarchy. Flavor: JavaScript.
• Debuggex - Create railroad diagrams. Flavors: JavaScript, PCRE, Python.
• Regexper - static)] - Create railroad diagrams. Flavor: JavaScript.