PHP

A standards compliant HTML filter library written in PHP. HTML Purifier will not only remove all malicious code (XSS) with a thoroughly audited, secure yet permissive whitelist, but it will also make sure your documents are standards compliant.

Composer is a tool for dependency management in PHP. It allows you to declare the libraries your project depends on and it will manage (install/update) them for you.

phpMussel is a PHP script designed to detect trojans, viruses, malware and other threats within files uploaded to your system wherever the script is hooked, based on the signatures of ClamAV and others. Works for any system with PHP+PCRE installed.

A free sitemaps generator that generates RSS-based, TXT-based and HTML-based sitemap files. It will spider your website and also your filesystem.

Silex is a PHP microframework featuring an intuitive and concise API, an extension system, a service container, a services type provider, a controller type provider, and more.

A wrapper collection for GD library in PHP. Defines a set of methods for flip, crop, resize, stamp and more, easily.

A PHP class for querying the Twitter API and rendering tweets as an HTML list.

CalendR is an object oriented Calendar management library on top of PHP5.3+ Date objects. Use it to deal with all your needs for calendars and events.

A portable public domain password hashing framework for use in PHP applications.

Admidio is a free open source user management system for websites of organizations and groups. The system has a flexible role model. The system contains several modules such as member lists, event manager, guestbook, photo album and download area.