Awesome PHP

A curated list of amazingly awesome PHP libraries, resources and shiny things.

• Awesome PHP
  • Package Management
  • Package Management Extras
  • Frameworks
  • Framework Extras
  • Framework Components
  • Micro Frameworks
  • Micro Framework Extras
  • Templating
  • Static Site Generators
  • HTTP
  • URL
  • Email
  • Files
  • Streams
  • Dependency Injection
  • Imagery
  • Testing
  • Documentation
  • Security
  • Code Analysis
  • Build Tools
  • Task Runners
  • Asset Management
  • Geolocation
  • Date and Time
  • Event
  • Logging
  • E-commerce
  • PDF
  • ORM and Datamapping
  • NoSQL
  • Queue
  • Search
  • Command Line
  • Authentication
  • Markup
  • Text and Numbers
  • Filtering and Validation
  • REST and API
  • Caching
  • Data Structure and Storage
  • Notifications
  • Deployment
  • Third Party APIs
  • Miscellaneous
  • Development Software
  • Web Tools
• Resources
  • Websites
  • Books
  • Web Reading
  • PHP Reading
  • PHP Internals Reading
• Contributing

Package Management

Libraries for package and dependency management.

• Composer/Packagist - A package and dependency manager.
• Composer Installers - A multi framework Composer library installer.

Package Management Extras

Extras related to package management.

• Satis - A static Composer repository generator.
• Composition - A library to check your Composer environment at runtime.
• Poser - A Composer class aliasing library.
• Version - A parsing and comparison library for semantic versioning.
• NameSpacer - A library to convert from underscores to namespaces.
• Patch Installer - A library to install patches using Composer.
• Composer Checker - A tool to validate Composer configurations.

Frameworks

Web development frameworks.

• Symfony2 - A framework comprised of individual components.
• Zend Framework 2 - Another framework comprised of individual components.
• Laravel 4 - A simple PHP framework.
• Aura PHP - A framework of independent components.
• Phalcon - A framework implemented as a C extension.

Framework Extras

Extras related to web development frameworks.

• Symfony CMF - A Content Management Framework to create custom CMS.
• Knp RAD Bundle - A Rapid Application Development (RAD) bundle for Symfony 2.

Framework Components

Standalone component from web development frameworks.

• Symfony2 Components - The components that make Symfony2.
• Zend Framework 2 Components - The components that make ZF2.
• Aura Components - A package of PHP 5.4 components.
• Hoa Project - Another package of PHP components.

Micro Frameworks

Micro frameworks and routers.

• Silex - A micro framework built around Symfony2 components.
• Slim - Another simple micro framework.
• Bullet PHP - A micro framework for building REST APIs.
• Fast Route - A fast routing library.
• Pux - Another fast routing library.

Micro Framework Extras

Extras related to micro frameworks and routers.

• Silex Skeleton - A project skeleton for Silex.
• Silex Web Profiler - A web debug toolbar for Silex.
• Stack - A library of stackable middleware for Silex/Symfony.
• Slim Skeleton - A skeleton for Slim.
• Slim View - A collection of custom views for Slim.
• Slim Middleware - A collection of custom middleware for Slim.

Templating

Libraries and tools for templating and lexing.

• Twig - A comprehensive templating language.
• Twig Cache Extension - A template fragment cache library for Twig.
• Mustache - A PHP implementation of the Mustache template language.
• Phly Mustache - Another PHP implementation of the Mustache template language.
• MtHaml - A PHP implementation of the HAML template language.
• Plates - A native PHP templating library.
• Lex - A lightweight template parser.

Static Site Generators

Tools for pre-processing content to generate web pages.

• Sculpin - A tool that converts Markdown and Twig into static HTML.
• Phrozn - Another tool that converts Textile, Markdown and Twig into HTML.

HTTP

Libraries for working with HTTP and scraping websites.

• Guzzle - A HTTP client.
• Buzz - Another HTTP client.
• Requests - A simple HTTP library.
• Goutte - A simple web scraper.
• PHP VCR - A library for recording and replaying HTTP requests.

URL

Libraries for parsing URLs.

• Purl - A URL manipulation library.
• PHP Domain Parser - A domain suffix parser library.

Email

Libraries for sending and parsing email.

• SwiftMailer - A mailer solution.
• PHPMailer - Another mailer solution.
• Fetch - An IMAP library.
• Email Reply Parser - An email reply parser library.
• Stampie - A library for email services such as SendGrid, PostMark, MailGun and Mandrill.

Files

Libraries for file manipulation and MIME type detection.

• Gaufrette - A filesystem abstraction layer.
• Flysystem - Another filesystem abstraction layer.
• Canal - A library to determine internet media types.
• Apache MIME Types - A library that parses Apache MIME types.
• Ferret - A MIME detection library.
• Hoa Mime - Another MIME detection library.
• Lurker - A resource tracking library.
• PHP File Locator - A library for locating files in large projects.
• PHP FFmpeg - A wrapper for the FFmpeg video library.
• CSV - A CSV data manipulation library.
• Cartographer - A sitemap generation library.

Streams

Libraries for working with streams.

• Streamer - A simple object-orientated stream wrapper library.

Dependency Injection

Libraries that implement the dependency injection design pattern.

• Pimple - A tiny dependency injection container.
• Auryn - Another dependency injection container.
• Orno Di - Another flexible dependency injection container.
• PHP DI - A dependency injection implementation using annotations.
• Acclimate - A common interface to dependency injection containers and service locators.

Imagery

Libraries for manipulating images.

• Imagine - An image manipulation library.
• PHP Image Workshop - Another image manipulation library.
• Intervention Image - Another image manipulation library.
• GIF Frame Extractor - A library to extract GIF animation frame information.
• GIF Creator - A library to create GIF animations from multiple images.
• Image With Text - A library for embedding text into images.
• Color Extractor - A library for extracting colours from images.

Testing

Libraries for testing codebases and generating test data.

• PHPUnit - A unit testing framework.
• DBUnit - A database testing library for PHPUnit.
• ParaTest - A parallel testing library for PHPUnit.
• PHPSpec - A design by specification unit testing library.
• Codeception - A full stack testing framework.
• Atoum - A simple testing library.
• Mockery - A mock object library for testing.
• Phake - Another mock object library for testing.
• Parody - Yet another mock object library for testing.
• Sismo - A continuous testing server library.
• Faker - A fake data generator library.
• Samsui - Another fake data generator library.
• Alice - An expressive fixture generation library.
• Behat - A behaviour driven development (BDD) testing framework.
• Pho - Another behaviour driven development testing framework.
• Mink - Web acceptance testing.
• HTTP Mock - A library for mocking HTTP requests in unit tests.
• VFS Stream - A virtual filesystem stream wrapper for testing.
• VFS - Another virtual filesystem for testing.
• Locust - A modern load test library written in Python.
• Travis CI - A continuous integration platform.
• PHPCI - An open source continuous integration platform for PHP.

Documentation

Libraries for generating project documentation.

• Sami - An API documentation generator.
• APIGen - Another API documentation generator.
• PHP Documentor 2 - A documentation generator.

Security

Libraries for generating secure random numbers, encrypting data and scanning for vulnerabilities.

• HTML Purifier - A standards compliant HTML filter.
• RandomLib - A library for generating random numbers and strings.
• True Random - A library that generates random numbers using www.random.org.
• SecurityMultiTool - A PHP security library.
• Password Compat - A compatibility library for the new PHP 5.5 password functions.
• PHPAss - A portable password hashing framework.
• PHP Password Lib - A library for generating and validating passwords.
• Password Policy - A password policy library for PHP and JavaScript.
• Password Validator - A library for validating and upgrading password hashes.
• PHPSecLib - A pure PHP secure communications library.
• TCrypto - A simple encrypted key-value storage library.
• PHP IDS - A structured PHP security layer.
• PHP SSH - An experimental object orientated SSH wrapper library.
• IniScan - A tool that scans PHP INI files for security.
• SensioLabs Security Check - A web tool to check your Composer dependecies for security advisories.
• Zed - An integrated penetration testing tool for web applications.

Code Analysis

Libraries and tools for analysing, parsing and manipulation codebases.

• PHP Parser - A PHP parser written in PHP.
• PHPPHP - A PHP VM implementation in PHP.
• PHPSandbox - A PHP sandbox environment.
• Dissect - A set of tools for lexical and syntactical analysis.
• PHP Mess Detector - A library that scans code for bugs, sub-optimal code, unused parameters and more.
• PHP Code Sniffer - A library that detects PHP, CSS and JS coding standard violations.
• PHPCPD - A library that detects copied and pasted code.
• PHP Analyser - A library for analysing PHP code to find bugs and errors.
• PHP CS Fixer - A coding standard fixer library.
• PHP Manipulator - A library for analysing and modifying PHP Source Code.
• PHP Metrics - A static metric library.
• PHP Refactoring Browser - A command line utility for refactoring PHP code.
• UBench - A simple micro benchmark library.
• Athletic - An annotation based benchmark framework.
• Mondrian - A code analysis tool using Graph Theory.
• PHP Debug Bar - A debugging toolbar.
• PHP Console - A web debugging console.
• Barbushin PHP Console - Another web debugging console using Google Chrome.
• PHPDBG - An interactive PHP debugger.
• Scrutinizer - A web tool to scrutinise PHP code.
• PHPLOC - A tool for quickly measuring the size of a PHP project.
• xDebug - A debug and profile tool for PHP.
• xHprof - Another profiling tool for PHP.

Build Tools

Project build and automation tools.

• Go - A simple PHP build tool.
• Bob - A simple project automation tool.
• Phake - A rake PHP clone library.
• Box - A utility to build PHAR files.
• Phing - A PHP project build system inspired by Apache Ant.

Task Runners

Libraries for automating and running tasks.

• Task - A pure PHP task runner inspired by Grunt and Gulp.
• Robo - A PHP Task runner with object-orientated configurations.
• Bldr - A PHP Task runner built on Symfony components.

Asset Management

Tools for managing, compressing and minifying website assets.

• Assetic - An asset manager pipeline library.
• Pipe - Another asset manager pipeline library.
• Munee - An asset optimiser library.
• JShrink - A JavaScript minifier library.
• Puli - A library for determining assets absolute paths.

Geolocation

Libraries for geocoding addresses and working with latitudes and longitudes.

• GeoCoder - A geocoding library.
• GeoTools - A library of geo-related tools.
• PHPGeo - A simple geo library.
• GeoJSON - A GeoJSON implementation.

Date and Time

Libraries for working with dates and times.

• Carbon - A simple DateTime API extension.
• ExpressiveDate - Another DateTime API extension.
• CalendR - A calendar management library.

Event

Libraries that are event-driven or implement non-blocking event loops.

• React - An event driven non-blocking I/O library.
• Rx.PHP - A reactive extension library.
• Ratchet - A web socket library.
• Hoa WebSocket - Another web socket library.
• Hoa EventSource - An event source library.
• Evenement - An event dispatcher library.
• FuelPHP Event - Another event dispatcher library.

Logging

Libraries for generating and working with log files.

• Monolog - A comprehensive logger.
• KLogger - An easy-to-use PSR-3 compliant logging class.

E-commerce

Libraries and applications for taking payments and building online e-commerce stores.

• OmniPay - A framework agnostic multi-gateway payment processing library.
• Payum - A payment abstraction library.
• Sylius - An open source e-commerce solution.
• Thelia - Another open source e-commerce solution.
• Money - A PHP implementation of Fowler's money pattern.
• Sebastian Money - Another library for working with monetary values.
• Swap - An exchange rates library.

PDF

Libraries and software for working with PDF files.

• Snappy - A PDF and image generation library.
• WKHTMLToPDF - A tool to convert HTML to PDF.

ORM and Datamapping

Libraries that implement object-relational mapping or datamapping techniques.

• Doctrine - A comprehensive DBAL and ORM.
• Doctrine Migrations - A migration library for Doctrine.
• Doctrine Extensions - A collection of Doctrine behavioural extensions.
• Propel - A fast ORM.
• Eloquent - The Laravel 4 ORM.
• Baum - A nested set implementation for Eloquent.
• Spot - A MySQL datamapper ORM.
• RedBean - A lightweight, configuration-less ORM.
• PHP ActiveRecord - A PHP Active Record implementation.
• Paris and Idiorm - A minimalist database library.
• Pomm - An Object Model Manager for PostgreSQL.
• Migrations - A migration management library.
• PHPMig - Another migration management library.
• Phinx - Another database migration library.

NoSQL

Libraries for working with "NoSQL" backends.

• MongoQB - A MongoDB query builder library.
• Monga - A MongoDB abstraction library.
• Predis - A feature complete Redis library.

Queue

Libraries for working with event and task queues.

• Pheanstalk - A Beanstalkd client library.
• PHP AMQP - A pure PHP AMQP library.
• Thumper - A RabbitMQ pattern library.
• Bernard - A multibackend abstraction library.

Search

Libraries and software for indexing and performing search queries on data.

• ElasticSearch PHP - The official client library for ElasticSearch.
• Elastica - A client library for ElasticSearch.
• Solarium - A client library for Solr.

Command Line

Libraries for building command line utilities.

• Boris - A tiny PHP REPL.
• PsySH - Another PHP REPL.
• Pecan - An event-driven, non-blocking shell.
• GetOpt - A command line opt parser.
• OptParse - Another command line opt parser.
• Commando - Another simple command line opt parser.
• GetOptionKit - Another command line opt parser.
• Cron Expression - A library to calculate cron run dates.
• ShellWrap - A simple command line wrapper library.
• Hoa Console - Another command line library.
• Shunt - A library for running commands in parallel on multiple remote machines.

Authentication

Libraries for implementing authentications schemes.

• Sentry - A framework agnostic authentication & authorisation library.
• Sentry Social - A library for social network authentication.
• OPAuth - A multi-provider authentication framework.
• OAuth2 - An OAuth2 authentication server, resource server and client library.
• PHP oAuthLib - Another OAuth library.
• TwitterOAuth - A Twitter OAuth library.
• TwitterSDK - A fully tested Twitter SDK.
• Hawk - A Hawk HTTP authentication library.

Markup

Libraries for working with markup.

• Decoda - A lightweight markup parser library.
• PHP Markdown - A Markdown parser.
• Dflydev Markdown - Another Markdown parser.
• Parsedown - Another Markdown parser.
• Ciconia - Another Markdown parser that supports Github flavoured Markdown.
• Markdown - An extensible Markdown parser.
• HTML5 PHP - An HTML5 parser and serializer library.

Text and Numbers

Libraries for parsing and manipulating text and numbers.

• ANSI to HTML5 - An ANSI to HTML5 convertor library.
• Patchwork UTF-8 - A portable library for working with UTF-8 strings.
• Hoa String - Another UTF-8 string library.
• Stringy - A string manipulation library with multibyte support.
• Numbers PHP - A library for working with numbers.
• Math - A library for working with large numbers.
• Color Jizz - A library for manipulating and converting colours.
• UUID - A library for generating UUIDs.
• Slugify - A library to convert strings to slugs.
• Urlify - A PHP port of Django's URLify.js.
• Text - A text manipulation library.
• PHP Units of Measure - A library for converting between units of measure.
• PHP Conversion - Another library for converting between units of measure.
• SQL Formatter - A library for formatting SQL statements.
• ByteUnits - A library to parse, format and convert byte units in binary and metric systems.
• UA Parser - A library for parsing user agent strings.
• LibPhoneNumber for PHP - A PHP implementation of Google's phone number handling library.

Filtering and Validation

Libraries for filtering and validating data.

• Filterus - A simple PHP filtering library.
• Respect Validate - A simple validation library.
• Valitron - Another validation library.
• Upload - A library for handling file uploads and validation.
• DMS Filter - An annotation filtering library.
• MetaYaml - A schema validation library that supports YAML, JSON and XML.
• ISO-codes - A library for validating various ISO and ZIP codes (IBAN, SWIFT/BIC, BBAN, VAT, SSN, UKNIN).

REST and API

Libraries and web tools for developing REST-ful APIs.

• Apigility - An API builder built with Zend Framework 2.
• Hateoas - A HATEOAS REST web service library.
• HAL - A Hypertext Application Language (HAL) builder library.
• Negotiation - A content negotiation library.

Caching

Libraries for caching data.

• Alternative PHP Cache (APC) - Open opcode cache for PHP.
• Cache - A caching library (part of Doctrine).
• Stash - Another library for caching.

Data Structure and Storage

Libraries that implement data structure or storage techniques.

• Ardent - A library of data structures.
• PHP Collections - A simple collections library.
• Serializer - A library for serialising and de-serialising data.
• PHP Object Storage - A library for object storage.
• Fractal - A library for converting complex data structures to JSON output.
• Pinq - PHP Integrated query, a real Linq library for PHP.

Notifications

Libraries for working with notification software.

• Nod - A notification library (e.g., Growl).
• Notificato - A library for handling push notifications.
• Notification Pusher - A standalone library for device push notifications.
• Notificator - A lightweight notification library.

Deployment

• Pomander - A deployment tool for PHP applications.
• Rocketeer - A fast and easy deployer for the PHP world.

Third Party APIs

Libraries for accessing third party APIs.

• Amazon Web Service SDK - The official PHP AWS SDK library.
• S3 Stream Wrapper - A stream wrapper library for Amazon S3.
• Stripe - The official Stripe PHP library.
• Campaign Monitor - The official Campaign Monitor PHP library.
• Digital Ocean - A library to interface with the Digital Ocean API.
• Github - A library to interface with the Github API.
• PHP Github API - Another library to interface with the Github API.
• Twitter OAuth - A library to interface with Twitter's OAuth workflow.
• Twitter REST - A library to interact with Twitter's REST API.
• Dropbox SDK - The official PHP Dropbox SDK library.
• Twilio - The official Twilio PHP REST API.
• HybridAuth - An open source social sign on library.

Miscellaneous

Useful libraries or tools that don't fit in the categories above.

• Spork - A process forking library.
• JSON Lint - A JSON lint utility.
• JSONPCallbackValidator - A library for validating JSONP callbacks.
• KnpMenu - A menu library.
• Pagerfanta - A pagination library.
• Ruler - A simple stateless production rules engine.
• LiteCQRS - A CQRS (Command Query Responsibility Separation) library.
• Sslurp - A library that makes dealing with SSL suck less.
• PHP Option An option type library.
• Metrics - A simple metrics API library.
• Sabre VObject - A library for parsing VCard and iCalendar objects.
• Annotations - An annotations library (part of Doctrine).
• Whoops - A pretty error handling library.
• Finite - A simple PHP finite state machine.
• LadyBug - A dumper library.
• Plum - A deployer library.
• Procrastinator - A library for running time consuming tasks.
• Compose - A function composition library.
• SuperClosure - A library that allows Closures to be serialized.
• Jumper - A remote service executor library.
• Underscore - A PHP port of the Underscore JS library.
• PHP PassBook - A PHP library for iOS PassBook.
• PHP Expression - A PHP expression language.
• RMT - A library for versioning and releasing software.
• Wise - A configuration manager.
• Opengraph - An opengraph library.
• Essence - A library for extracting web media.
• Embera - An Oembed consumer library.
• Graphviz - A Graphviz library.
• Monad PHP - A simple Monad library.
• Flux - A regular expression building library.
• Patchwork - A library for redefining userland functions.
• Galapagos - Evolutionary language transformation.
• Design Patterns PHP - A repository of software patterns implemented in PHP.
• PHPCR - A PHP port of the Java Content Repository (JCR).
• Functional PHP - A functional programming library.
• ClassPreloader - A library for optimising autoloading.
• Lib Country - A library for country and subdivision data.
• Lib Accessor - A library for simplifying accessors.
• PHPStack - A TCP/IP stack proof of concept written in PHP.
• Nmap - A PHP wrapper around Nmap.
• Code Mover - A library for moving code.
• Iter - A library that provides iteration primatives using generators.
• Lambda PHP - A Lambda calculus interpreter in PHP.
• Country List - A list of all countries with names and ISO 3166-1 codes.
• PHP-GPIO - A library for playing with the Raspberry PI's GPIO pins.

Development Software

Software for creating a development environment.

• HomeBrew - A package manager for OSX.
• HomeBrew PHP - A PHP tap for HomeBrew.
• PHP OSX - A PHP installer for OSX.
• HipHop PHP - A Virtual Machine, Runtime and JIT for PHP by Facebook.
• Vagrant - A portable development environment utility.
• Ansible - A radically simple orchestration framework.
• Puppet - A server automation framework and application.
• Chef - A systems integration framework.
• SaltStack - An infrastructure management tool.
• PHP Brew - A PHP version manager and installer.
• PHP Env - Another PHP version manager.
• PHP Switch - Another version manager.
• PHP Build - Another PHP version installer.
• CodeKit - A general web development tool.
• HTTPie - A command line alternative to cURL written in Python.
• Backup - A server backup tool written in Ruby.

Web Tools

Web-based tools.

• PuPHPet - A web tool for building PHP development virtual machines.
• Protobox - Another web tool for building PHP development virtual machines.
• Phansible - A web tool for building PHP development virtual machines with Ansible.
• 3V4L - An online PHP shell.
• DBV - A database version control application.
• PHP Queue - An application for managing queueing backends.
• Composer as a Service - A tool for downloading Composer packages as a zip file.
• MailCatcher - A web tool for capturing and viewing emails.

Resources

Various resources, such as books, websites and articles, for improving your PHP development skills and knowledge.

Websites

Useful web and PHP-related websites and newsletters.

• PHP The Right Way - A PHP best practice quick reference guide.
• PHP Best Practices - A PHP best practice guide.
• PHP Weekly - A weekly PHP newsletter.
• PHP Security - A guide to PHP security.
• PHP Internals - A book about the PHP internals.
• PHP FIG - The PHP Framework Interoperability Group.
• The Open Web Application Security Project (OWASP) - An open software security community.
• WebSec IO - A web security community resource.
• Web Advent - An advent calendar for web developers.
• Mozilla Developer Network - A website of shared knowledge for the open web.
• HTML5Rocks - A resource for open web HTML5 developers.
• Programming with Anthony - A video series by Anthony Ferrara.
• Seven PHP - A website that interviews members of the PHP community.

Books

Fantastic books and e-books.

• Scaling PHP Applications - An ebook about scaling PHP applications by Steve Corona.
• Grumpy PHPUnit - A book about unit testing with PHPUnit by Chris Hartjes.
• Mastering Object-Orientated PHP - A book about object-orientated PHP by Brandon Savage.
• Signaling PHP - A book about catching PCNTL signals in CLI scripts by Cal Evans.
• Understanding Computation - A book about computation theory by Tom Stuart.
• The Linux Command Line - A book about the Linux command line by William Shotts.
• Securing PHP: Core Concepts - An ebook about common security terms and practices for PHP by Chris Cornutt.

Web Reading

General web-development-related reading materials.

• OWASP PHP Security Cheat Sheet - A PHP security cheatsheet.
• C is for Cookie, H is for Hacker - An article about cookies and security.
• You Blew It Loading Your Login Form Over HTTP - An article about using HTTPS correctly with login forms.
• How HTTPS Secures Your Connection - An article explaining how TLS/SSL secures your connection.
• How to Build a Secure Remember Me Feature - An article on how to build a secure remember me feature.
• A Beginners Guide to HTTP Cache Headers - An article about HTTP cache headers.
• Beyond Series 1 2 3 4 - A series of articles about programming by Anthony Ferrara.
• Semantic Versioning - A website explaining semantic versioning.
• Atlassian Git Tutorials - A series of Git tutorials.
• Hg Init - A series of Mercurial tutorials.

PHP Reading

PHP-releated reading materials.

• Create Your Own PHP Framework - A series of articles on how to make your own PHP framework by Fabien Potencier.
• Seven Ways to Screw Up BCrypt - An article about correct BCrypt implementation.
• Preventing CSRF Attacks - An article on preventing CSRF attacks.
• Don't Worry About BREACH - An article about the BREACH hack and CSRF tokens.
• On PHP 5.3, Lamda Functions and Closures - An article about lambda functions and closures.
• Use Env - An article about using the unix environment helper.
• Composer Primer - A Composer primer.
• Composer Versioning - An article about Composer versioning.
• Composer Stability Flags - An article about Composer stability flags.
• Innocent Villagefolk or a Pillagin’ Pirate? - An article about PHP taking ideas from other language.
• Predicting Random Numbers in PHP - An article about generating random numbers.
• A 20 Point List for Preventing XSS in PHP - An article about preventing XSS.
• PHP Sucks! But I Like It! - An article about the pros and cons of PHP.
• PHP Is Much Better Than You Think - An article about the PHP language and ecosystem.

PHP Internals Reading

Reading materials related to the PHP internals or performance.

• PHP RFCs - The home of PHP RFCs (Request for Comments).
• Print vs Echo, Which One is Faster? - An article about print and echo performance.
• The PHP Ternary Operator. Fast or Not? - An article ternary performance.
• Disproving the Single Quotes Myth - An article about performance of single and double quoted strings.
• You're Being Lied To - An article about internal ZVALs.
• How Long is a Piece of String - An article about string internals.
• Understanding OpCodes - An article about opcodes.
• How Foreach Works - A detailed StackOverflow answer about foreach.
• When Does Foreach Copy? - An article about the internals of foreach.
• How Big Are PHP Arrays (And Values) Really? - An article about array internals.
• PHP Evaluation Order - An article about evaluation order in PHP.
• PHP Source Code for Developers: 1 2 3 4 - A series about the PHP source code.
• Collecting Garbage: 1 2 3 - A series about the PHP garbage collection internals.

Contributing

Please see CONTRIBUTING for details.