• Break: For forward compatibility, you should change your deployment scripts to run composer install --no-dev. The install command will install dev dependencies by default starting in the next release
• Break: The update command now has --dev enabled by default. --no-dev can be used to update without dev requirements, but it will create an incomplete lock file and is discouraged
• Break: Removed support for lock files created before 2012-09-15 due to their outdated unusable format
• Added prefer-stable flag to pick stable packages over unstable ones when possible
• Added preferred-install config option to always enable --prefer-source or --prefer-dist
• Added diagnose command to to system/network checks and find common problems
• Added wildcard support in the update whitelist, e.g. to update all packages of a vendor do composer update vendor/*
• Added archive command to archive the current directory or a given package
• Added run-script command to manually trigger scripts
• Added proprietary as valid license identifier for non-free code
• Added a php-64bit platform package that you can require to force a 64bit php
• Added a lib-ICU platform package
• Added a new official package type project for project-bootstrapping packages
• Added zip/dist local cache to speed up repetitive installations
• Added post-autoload-dump script event
• Added Event::getDevMode to let script handlers know if dev requirements are being installed
• Added discard-changes config option to control the default behavior when updating "dirty" dependencies
• Added use-include-path config option to make the autoloader look for files in the include path too
• Added cache-ttl, cache-files-ttl and cache-files-maxsize config option
• Added cache-dir, cache-files-dir, cache-repo-dir and cache-vcs-dir config option
• Added support for using http(s) authentication to non-github repos
• Added support for using multiple autoloaders at once (e.g. PHPUnit + application both using Composer autoloader)
• Added support for .inc files for classmap autoloading (legacy support, do not do this on new projects!)
• Added support for version constraints in show command, e.g. composer show monolog/monolog 1.4.*
• Added support for svn repositories containing packages in a deeper path (see package-path option)
• Added an artifact repository to scan a directory containing zipped packages
• Added --no-dev flag to install and update commands
• Added --stability (-s) flag to create-project to lower the required stability
• Added --no-progress to install and update to hide the progress indicators
• Added --available (-a) flag to the show command to display only available packages
• Added --name-only (-N) flag to the show command to show only package names (one per line, no formatting)
• Added --optimize-autoloader (-o) flag to optimize the autoloader from the install and update commands
• Added -vv and -vvv flags to get more verbose output, can be useful to debug some issues
• Added COMPOSER_NO_INTERACTION env var to do the equivalent of --no-interaction (should be set on build boxes, CI, PaaS)
• Added PHP 5.2 compatibility to the autoloader configuration files so they can be used to configure another autoloader
• Fixed handling of platform requirements of the root package when installing from lock
• Fixed handling of require-dev dependencies
• Fixed handling of unstable packages that should be downgraded to stable packages when updating to new version constraints
• Fixed parsing of the ~ operator combined with unstable versions
• Fixed the require command corrupting the json if the new requirement was invalid
• Fixed support of aliases used together with <version>#<reference> constraints
• Improved output of dependency solver problems by grouping versions of a package together
• Improved performance of classmap generation
• Improved mercurial support in various places
• Improved lock file format to minimize unnecessary diffs
• Improved the config command to support all options
• Improved the coverage of the validate command
• Tons of minor bug fixes and improvements