Easy, actually.
Details of the Cloudflare outage on July 2, 2019
Why are regular expressions difficult?
terkelg/globrex: Glob to regular expression with support for extended globs.


Regular expression pattern ICD-10 & ICD-10 diagnosis codes


Microsoft/BlingFire: A lightning fast Finite State machine and REgular expression manipulation library.
Applicative Regular Expressions using the Free Alternative · in Code
jkutner/saferegex: A tool for testing regular expressions for ReDoS vulnerabilities.


Chromium Blog: Irregexp, Google Chrome's New Regexp Implementation
Exploiting Regular Expressions – Somdev Sangwan – Medium


Home Page - Hyperscan.io
intel/hyperscan: High-performance regular expression matching library
Hyperscan: A Fast Multi-pattern Regex Matcher for Modern CPUs (PDF)
Paper: Hyperscan: A Fast Multi-pattern Regex Matcher for Modern CPUs – Branch Free
Don’t fear the regex - All this
Daring Fireball: On Getting Started With Regular Expressions
JavaScript Regular Expressions for Regular People ← Alligator.io
Regular expressions (`RegExp`) • JavaScript for impatient programmers (beta)
New JavaScript Features That Will Change How You Write Regex — Smashing Magazine
Nevod - pattern-based text search


4.7. Validate ISO 8601 Dates and Times - Regular Expressions Cookbook, 2nd Edition [Book]
^(-?(?:[1-9][0-9]*)?[0-9]{4})-(1[0-2]|0[1-9])-(3[01]|0[1-9]|[12][0-9])↵ T(2[0-3]|[01][0-9]):([0-5][0-9]):([0-5][0-9])(\.[0-9]+)?↵ (Z|[+-](?:2[0-3]|[01][0-9]):[0-5][0-9])?$
segmentio/glob: Glob matcher based on Go's path.Match()
BurntSushi/regex-automata: A low level regular expression library that uses deterministic finite automata.


pampy/README.md at master · santinic/pampy
Gregable.com: Regular Expression Crossword Puzzle
Catastrophic Backtracking—Exponential Matches—ReDos


Derivatives of Regular Expressions (2007) | Hacker News
Derivatives of Regular Expressions | Lambda the Ultimate
TRE: A Regex Engine with Approximate Matching - Ducktape’s blog
Easy Dynamic Regular Expressions with Tagged Template Literals and Proxies | Lea Verou
Regex that only matches itself - Programming Puzzles & Code Golf Stack Exchange
Dr. Regex: How to match "A B C" where A+B=C: The Beast Reborn


CppCon 2018: Hana Dusíková “Compile Time Regular Expressions” - programming
Rosie Pattern Language / Rosie · GitLab
govalidator/patterns.go at master · asaskevich/govalidator
mathiasbynens/emoji-regex: A regular expression to match all Emoji-only symbols as per the Unicode Standard.
No Magic: Regular Expressions, Part 3
No Magic: Regular Expressions
No Magic: Regular Expressions, Part 2


HTML5Pattern is a source of common regexes for <input pattern="">
shinnn/github-username-regex: A regular expression that only matches a currently valid Github username
The Best of Fluent: /Reg(exp){2}lained/: Demystifying Regular Expressions - O'Reilly Media Free, Live Events
Chomsky hierarchy - Wikipedia
The Perl Journal One Liners - The Perl Journal, Spring 1999
"Regular expressions are to strings what math is to numbers." --Andrew Clinick, discussing what Microsoft thinks of Perl in http://www.microsoft.com/sitebuilder/magazine/clinick_perl.asp.
substack/safe-regex: detect possibly catastrophic, exponential-time regular expressions
Using Regex for Text Manipulation in Python


build-your-own-x/README.md at master · danistefanovic/build-your-own-x
Regex Dictionary by Lou Hevly


arnoldrobbins/mcilroy-regex: Doug McIlroy's C++ regular expression matching library
Beyond Regular Expressions: An Introduction to Parsing Context Free Grammars
Regular Expression Matching with a Trigram Index
Regular Expression Matching in the Wild
Regular Expression Matching: the Virtual Machine Approach
The GNU Awk User’s Guide: Ranges and Locales
micromatch/micromatch: Highly optimized wildcard and glob matching library. Faster, drop-in replacement to minimatch and multimatch. Used by babel core, yarn, jest, browser-sync, documentation.js, stylelint, nyc, and many others!


rust-lang/regex: An implementation of regular expressions for Rust. This implementation uses finite automata and guarantees linear time matching on all inputs.
Regex Cheatsheet
Regular expressions: how do they work?
kevva/url-regex: Regular expression for matching URLs
Using Regular Expressions to Find Cthulhu 🐙


UTS #18: Unicode Regular Expressions
No Magic: Regular Expressions, Part 3
No Magic: Regular Expressions, Part 2
No Magic: Regular Expressions
How Regexes Work
Build a Regex Engine in Less than 40 Lines of Code › Nick Drane
Regular Expression Matching Can Be Simple And Fast
DasSur.ma – My most useful RegExp trick


dhellmann/presentation-regexes-fear: Presentation: Regular Expressions Are Nothing to Fear
So you think you can validate email addresses A journey down RFC5321 - YouTube
Parsing: a timeline -- V3.0
Exploring the Linguistics Behind Regular Expressions
Python Regular Expressions Cheat Sheet


lookaheads (and lookbehinds) in JavaScript regular expressions
Regexp Syntax Summary
Lookahead and Lookbehind Tutorial—Tips &Tricks
Exploring the Linguistics Behind Regular Expressions


Regular Expression Matching Can Be Simple And Fast
ECMAScript regular expressions are getting better! · Mathias Bynens
ES2018: RegExp named capture groups
ES2018: RegExp Unicode property escapes
ES2018: RegExp lookbehind assertions
ES2018: `s` (`dotAll`) flag for regular expressions


free-programming-books/free-programming-books.md at master · EbookFoundation/free-programming-books
hosseinmousavi/Regex.Persian.Language: Collection of Regex for validating, filtering, sanitizing and finding Persian strings
Ftfy – fix Unicode that's broken in various ways | Hacker News
[^ -~]
chalk/ansi-regex: Regular expression for matching ANSI escape codes


Python – Regular Expressions Practical Guide – Developers Area
Python – Regular Expressions Practical Guide – Developers Area
Comparison of regular expression engines - Wikipedia
An introduction to regular expressions - O'Reilly Media
Dr. Regex: Match Nested Brackets with Regex: A new approach
GitHub - mndrix/regex: Regular expressions for Prolog
Regex was taking 5 days to run. So I built a tool that did it in 15 minutes.
Build a Regex Engine in Less than 40 Lines of Code › Nick Drane
Regular Expressions for Data Scientists


Introduction to Regular Expressions in Python
Structural Regular Expressions


AWS WAF Now Supports Regular Expressions (Regex)
code golf - Regex that only matches itself - Programming Puzzles & Code Golf Stack Exchange
sindresorhus/matcher: Simple wildcard matching
sindresorhus/globby: User-friendly glob matching
eriknyquist/librxvm: non-backtracking NFA-based regular expression library, for C and Python


opennota/re2dfa: Transform regular expressions into finite state machines and output Go source code
dveselov/python-pire: Python interface to PIRE


Regular Expressions and Grouping Sets
V8 JavaScript Engine: Upcoming RegExp Features
Language Tags: Addison Phillips Java regexp for language tags


GitHub - zeeshanu/learn-regex: Learn regex the easy way
Regular Expressions Primer and Resource - Advanced Text Searching
GitHub - iogf/crocs: Write regex using pure python class/function syntax and test it better. (Regex for humans).
MIT Mystery Hunt Puzzle Index: Puzzle Data
BBC Radio 4 - Today - Puzzle for Today
Replacing a Complex Regular Expression with a Simple Parser
FuzzyFinder - in 10 lines of Python - Brain Spill


re — Regular Expressions — PyMOTW 3
OWASP Validation Regex Repository - OWASP
Regex Set Scanning with Hyperscan and RE2::Set | 01.org
Java 101: Regular expressions in Java, Part 1 | JavaWorld
Reparse — Reparse 3.0 documentation
I Knew How To Validate An Email Address Until I Read The RFC | You’ve Been Haacked
wregex - How Regular Expression Engines Work


Update: re_search.py Version 0.0.7 | Didier Stevens
The New ‘Absent Operator’ in Ruby’s Regular Expressions – Ruby Inside – Medium
Converting glob patterns to efficient regexes in Perl and JavaScript | mauke [blogs.perl.org]


Java Standard Library — Scala Native 0.1 documentation
research!rsc: Glob Matching Can Be Simple And Fast Too
Beyond Regular Expressions - Lex and Yacc
Fuzzing is magic - Or how I found a panic in Rust's regex library
A comparison of regex engines – Rust Leipzig


#12818 (regex: badly needs fuzzing) – Boost C++ Libraries


V8 JavaScript Engine: Speeding up V8 Regular Expressions
Let’s Stop Ascribing Meaning to Code Points | Hacker News
GitHub - laurikari/tre: The approximate regex matching library and agrep command line tool.


RegEx Face Off
lk-geimfari/expynent: A library that provides regex patterns. If you hate to write regular expressions, then expynent can help you.
RunKit + npm: regexgen
Yesterdays Regex — Geek&Poke
Regular Expressions for Google Analytics - Regular-Expressions-Google-Analytics.pdf
Runaway Regular Expressions: Catastrophic Backtracking
ripgrep code review
Adventures in the land of substrings and RegExps.


Regex Hub - Useful Regex Patterns
RegexOne - Learn Regular Expressions - Lesson 1: An Introduction, and the ABCs
Visualizing Regular Expressions: regexper.com – Medium
Regex 101 | Hacker News
Big Performance Improvement for std.regex – The D Blog
Regex that only matches itself - Programming Puzzles & Code Golf Stack Exchange


Unicode property escapes in JavaScript regular expressions · Mathias Bynens
jamiejennings/rosie-pattern-language: Rosie Pattern Language (RPL) and the Rosie Pattern Engine
Recursive Regular Expression


rust-lang-nursery/regex: An implementation of regular expressions for Rust. This implementation uses finite automata and guarantees linear time matching on all inputs.
ripgrep is faster than {grep, ag, git grep, ucg, pt, sift} - Andrew Gallant's Blog
Demystifying The Regular Expression That Checks If A Number Is Prime – G'd Up Code
The 100% correct way to validate email addresses


SRL - Simple Regex Language
Google Code Archive - Long-term storage for Google Code Project Hosting.
why GNU grep is fast
s4ke/moar: Deterministic Regular Expressions with Backreferences
Maniagnosis - A deep dive into regular expression derivatives for lexical analysis
Ann: Typed regular expressions | Drup's thingies
Regular expression to match line that doesn't contain a word? - Stack Overflow
Validating Email Addresses with a Regex? Do yourself a favor and don’t – /dev/random
Apocalypse 5: Pattern Matching
kkos/oniguruma: regular expression library
Boost.Regex 5.1.1 - 1.61.0
A Regular Expression Matcher (2007) | Hacker News


moovweb/rubex: Super Fast Regex in Go
Stack Overflow Outage Postmortem | Hacker News
Stack Exchange Network Status — Outage Postmortem - July 20, 2016


Fast, Elegant Regexes in Haskell
Making sense of regular expressions


Eigenstate :: Implementing A Simple Regex Debugger
languagengine - Blog - Regex Edit Distance
Regular expressions you can read: A new visual syntax (and UI) — Medium
BurntSushi/rure-go: Go bindings to Rust's regex engine.


Debuggex: Online visual regex tester. JavaScript, Python, and PCRE.
regex - How to make perl regexes matches ASCII and Unicode - Stack Overflow
EReg - Haxe API
Practice Makes Regexp - New regexp book from Reuven Lerner
Elliot Chance - It's Impossible to Validate an Email Address
Best Practices for Regular Expressions - Codacy | Blog


mathiasbynens/regex-trie-cli - Create regular expression patterns based on a list of strings to be matched
Puzzle | LinkedIn Engineering
Hard code golf: Regex for divisibility by 7 - Programming Puzzles & Code Golf Stack Exchange
V8 JavaScript Engine: RegExp lookbehind assertions


Understanding the basics of Regular Expression
[no title]
kirbyfan64/rejit: A work-in-progress JIT-powered regex engine
CaptainCrowbar/unicorn-lib: Unicode library for C++
String Parsing in SQL
GitHub - akoumjian/datefinder: Find dates inside text using Python and get back datetime objects


How I fixed Atom - davidvgalbraith
alexflint/go-restructure: Match regular expressions into struct fields
regex cheat sheet at DuckDuckGo
Javarevisited: 10 examples of grep command in UNIX and Linux
d10/regjsgen · GitHub
jviereck/regjsparser · GitHub
mathiasbynens/regenerate · GitHub
mathiasbynens/regexpu-core · GitHub


Regex Crossword
Gregable: Regular Expression Crossword Puzzle
Email address validation and encodings
Shell scripting notes – searching matching filenames and matching content | Kev's Development Toolbox
Regular Expression Basics | BoTree Technologies
RegExp class - dart:core library - Dart API


Python's Hidden Regular Expression Gems | Armin Ronacher's Thoughts and Writings
Abandon - Validate Facebook URLs & Twitter Usernames with PHP Regular Expression


Siderite's Blog: Super Fast and Accurate string distance algorithm: Sift4
the-emacs-problem - steveyegge2
How We Match Regular Expressions | 01.org
LightboxTech/liblightgrep · GitHub
Hyperscan | 01.org
Exact String Matching Algorithms | HackerEarth
Introduction to regular expressions
Working with Email Addresses in SQL - Mode Blog


The Best Regex Trick
Fast String Matching | JW Player
Perl Regular Expression Matching is NP-Hard
Converting regular expressions into nondeterministic finite automata (NFAs): An implementation in Java
Pattern-matching regular expressions in Scheme using derivatives
yandex/pire · GitHub
Perl Incompatible Regular Expressions library
A regular expression converter - hokein/Automata.js · GitHub


fent/randexp.js @ GitHub
Create random strings that match a given regular expression.
Snobol Pattern Matching in Python
Character Model for the World Wide Web: String Matching and Searching
PCRE - Perl Compatible Regular Expressions
Syntax extensions and regular expressions for Rust - Andrew Gallant's Blog
regex - Regular expression for unicode in java 7 - Stack Overflow


New regular expression features in ECMAScript 6
Using wildcard matching in any programming language | RLV Blog
Dennis Yurichev: 23-Jul-2015: Fuzzy string matching + simplest possible spellchecking + hunting for typos and misspellings in Wikipedia.
Automatic Generation of Text Extraction Patterns from Examples
swift - NSRegularExpression regex replace Greek Unicode text - Stack Overflow
This Week in D: June 28, 2015
Ragel State Machine Compiler | Colm Networks
Five Invaluable Techniques to Improve Regex Performance : programming
Five Invaluable Techniques to Improve Regex Performance


RohitK89/LogScraper · GitHub
Xeger - More expressive regular expressions for JavaScript. Pronounced "zeeger"
Regexes: The Bad, the Better, and the Best : programming
Regexes: the Bad, the Better, and the Best
Alternatives To Regular Expressions
jonathantneal/regexp-escape · GitHub
Implementing Regular Expressions


Emojineering Part 2: Implementing Hashtag Emoji - Instagram Engineering
PatternMatcher | Android Developers


Python regex tokenization of Unicode string not working as expected - Stack Overflow
Unicode and Boost.Regex - 1.58.0
In search of the perfect URL validation regex
Is there a regular expression to detect a valid regular expression? - Stack Overflow


google/re2j · GitHub
neuront/python-reloon · GitHub
is.js - micro check library
Wrestling PCRE
Understanding Regular Expressions 2: Groups and Captures


Email Regex that works 99.99% | Hacker News
Email Regex - Everything About Email Regular Expression!
RegExp.prototype.unicode - JavaScript | MDN
Regular Expressions in T-SQL - SQLTeam.com
Regular Expressions in T-SQL - Ken Henderson's WebLog - Site Home - MSDN Blogs
SQL Server: Regular Expressions for Efficient SQL Querying


mathiasbynens/regexpu · GitHub
A source code transpiler that enables the use of ES6 Unicode regular expressions in ES5.
Unicode Regular Expression Engines // Speaker Deck
A JIT for grepping: jrep and rejit [LWN.net]
“grep was a private command of mine for quite a while before i made it public.” -Ken Thompson — Medium
Liniarc/regexProgram · GitHub


Automatic Generation of Text Extraction Patterns from Examples
'regex' tag wiki - Stack Overflow
Regular expression cheat sheet
cheatsheet - regex-cheatsheet.pdf
Regular Expression Cheat Sheet
[.NET Core] System.Text.RegularExpressions Source Code : programming


regex - Unicode expression failing in preg_match after php and apache update - Stack Overflow


Maybe regexp is the wrong tool for this job. I'm just saying. : programming
Full email validation regex (RFC 2822) | Hacker News
Mathias Bynens on Twitter: "Support for the ES6 `y` flag for sticky regular expressions just landed in V8: https://t.co/XVx6JMlLwT Coming soon to Chrome, Opera & Node!"
sunlightlabs/jellyfish · GitHub
a python library for doing approximate and phonetic matching of strings.


Unicode-aware regular expressions in ES6 · Mathias Bynens
What you should know about JavaScript regular expressions


sindresorhus/mapcode-regex · GitHub
Regular expression for matching mapcodes
charles leifer | Playing with Python Magic Methods to make a nicer Regex API
regex /(?x: (w+) s (w+) )/ hacker news at DuckDuckGo
Understanding and Using Regular Expressions


In search of the perfect URL validation regex
TCL Regular Expression Examples
hrothgar/lexitron · GitHub
regex on a english dictionary
TRE — The free and portable approximate regex matching library.
Comparison of regular expression engines - Wikipedia, the free encyclopedia
List of regular expression software - Wikipedia, the free encyclopedia
regex 2014.05.23 : Python Package Index


Andrew Gallant's Blog :: Syntax extensions and regular expressions for Rust
Regular Expressions without Fear - The Changelog
VerbalExpressions ♥ Open Source


How to correctly detect credit card type
gskinner.com: gBlog: RegExr v2: Build, Test, & Learn RegEx
Regex Tutorial—From Regex 101 to Advanced Regex
Rx - a backend for writing regex debuggers for Perl
Learn regular expressions in about 55 minutes - Sam Hughes
Mastering Python Regular Expressions by Félix López and Víctor Romero


Try Regex—an interactive regex tutorial
The regex that broke a server | Vlad Mihalcea's Blog
xkcd 1313: Regex Golf (Part 2: Infinite Problems)
The Regexinator: a Google Analytics Regex Filter Compiler - LunaMetrics
Solving a Regular Expression Crossword with Haskell, Part 1
Regular Expressions in ANS Forth


The Developer’s RegEx Survival Guide: 15 Rules for Making Sense of Regular Expressions
Windows with C++ - Using Regular Expressions with Modern C++
command center: Regular expressions in lexing and parsing
HTML5 Input Patterns and Invalid Regex
Regex Golf, xkcd, and Peter Norvig - Slashdot
xkcd: Regex Golf
Solution to xkcd 1313
thebinarysearchtree/regexpbuilderjs · GitHub
igrigorik/textquery · GitHub


Regex Golf - discussion on Hacker News
Regex Golf - discussion on Reddit
Regex Golf
Hexpress by krainboltgreene
andrewberls/regularity · GitHub
CommonRegex - A collection of common regular expressions bundled with an easy to use interface.


Rex @ rise4fun from Microsoft
../re/testregex.mm mm document
man/man1/testregex.html man page
The best online regular expression / RegEx testers and builder-tools as of 2013 | Technical Programming and Design
SLRE: Super Light Regular Expression library


Of running multiple regexp at once
JSON parser as a single Perl Regex
Parsing JSON with a single regex | brian d foy [blogs.perl.org]
Matt Swanson - How not to validate email addresses


Meet RegExpBuilder: Verbal Expressions' rich, older cousin - The Changelog
Official IETF regex for URLs
RFC 3986 - Uniform Resource Identifier (URI): Generic Syntax
thebinarysearchtree/RegExpBuilder - GitHub


A Recursive Regular Expression for Matching Regular Expressions - Abrazolica
Bitsets match regular expressions, compactly - Paul Khuong mostly on Lisp
12 Resources For Mastering Regular Expressions
Using Python's AST parser to create regular expressions from English
noprompt/frak · GitHub
Transform collections of strings into regular expressions
Build Regex - A Simple RegEx GUI


jehna/VerbalExpressions · GitHub
Just released a major update for my site. What do you guys think? | Hacker News
Love Rubular? Here are a few open source copycats to checkout. - The Changelog
Regex Crossword
046 Regex on Vimeo
Parsley: A Pattern-Matching Language Based on OMeta and Python - github


Finite State Machines and Regular Expressions - General Programming - Articles - Articles - GameDev.net
GROK regex test page
Standard GROK regex patterns


Learn Regular Expressions - Pony Foo
The true power of regular expressions
Counting with Regular Expressions - Abrazolica
Stop Validating Email Addresses With Your Complex Regex - davidcel.is
JavaScript Regular Expression Enlightenment - Tech.Pro
Stop Avoiding Regular Expressions Damn It - bradt.ca


Brain Dump (english): Arithmetic with Regexps
Why the hell am I building a product with a tiny market? - Debuggex
Best of Fluent 2012: /Reg(exp){2}lained/: Demystifying Regular Expressions - YouTube
An example driven guide to regular expressions | JoeJag :: Tech
Python, Catastrophic Regular Expressions and the GIL


Nested Regular Expressions explained | Linguistic forms
Details of Regular Expression Behavior
Bastards Book of Regular Expressions by Dan Nguyen [PDF/iPad/Kindle]
HTML5 Pattern
regexs for HTML5 input validation
REBEL - Kendall Frey's Website
Regular Expression Based Esoteric Language - a declarative programming language that works by iteratively replacing substrings
petere/pgpcre · GitHub


java - Cancelling a long running regex match? - Stack Overflow
Comparison of regular expression engines - Wikipedia, the free encyclopedia
Parsing Techniques - A Practical Guide | Hacker News
print "Me" -- portable perspectives
k-takata/Onigmo · GitHub
Ruby 2.0
Debuggex: A visual regular expression debugger
Can You Do the Regular Expression Crossword? - Slashdot
Security Briefs - Regular Expression Denial of Service Attacks and Defenses
Collaborative Manuscript Transcription: Bending Regular Expressions to Express Uncertainty
Regex Challenge - Week Twenty
chess move notation using the algebraic notation
A regular expression crossword puzzle [pdf]
Regex Challenge - Week Nineteen
all the valid HTML tag names in as few characters as possible


RegexOne - Learn regular expressions with interactive examples
Regular expressions - Rosetta Code
The 30 Minute Regex Tutorial - CodeProject
I don't like Regex... - CodeProject
Regex Challenge - Week Eighteen
check if a string is a valid IRC message sent to a user or channel
harthur/replace · GitHub
Command line search and replace utility (with js regex)
AT&T Research regex(3) regression tests
logentries/re2-java · GitHub
Vim Regular Expressions 101
Printable Regular Expressions Cheatsheet
Validate an E-Mail Address with PHP, the Right Way | Linux Journal

Number of links: 400

Also see links to other regex testing websites/programs on the Similiar Tools page.