Drupal - Open Source CMS drupal.org

Zimbra offers Open Source email server software and shared calendar for Linux and the Mac.

Zimbra provides open source email and calendar groupware software, Zimbra is a popular choice for Linux and Mac OS X email servers and supports SaaS deployment, appliances and virtualization platforms.

PostgreSQL: The world's most advanced open source database

The official site for PostgreSQL, the world's most advanced open source database

Simple Machines Forum - Free & open source community software

Simple Machines offers free open source software such as SMF, the powerful and easy to use community forum written in PHP. Start interesting discussions on your website!

CodePlex - Open Source Project Hosting

Microsoft's open source project hosting web site. You can use CodePlex to find open source software or create new projects to share with the world.

concrete5 - Free CMS Open Source Content Management System

Many content management systems are focused on developer or site owner needs, but concrete5 is a CMS that truly delivers the best to both worlds. An in-context editing toolbar makes it easy to make changes as you navigate the live website. A truly MVC architecture and API make it easy for developers to truly use the CMS as building blocks.

CMS Support for Drupal Open Source Acquia

Drupal is the world's largest open source CMS, making it easier to streamline your company's content management system. Learn how Acquia can help you!

OpenCart - Open Source Shopping Cart Solution

A free shopping cart system. OpenCart is an open source PHP-based online e-commerce solution.

TYPO3 - The Enterprise Open Source CMS - TYPO3 - The Enterprise Open Source CMS

TYPO3 - The Enterprise Open Source CMS

Open Source - Sendmail.com

Sendmail partners include a host of leading companies who share a proven track record of developing and delivering complimentary email products to provide added-value to the installed Sendmail environment

Red Hat The World's Open Source Leader

The World#39

Open Source Web Design - Download free web design templates.

Download and upload free web designs.

osTicket:: Open Source Support Ticket System

Open source support ticket system simple, lightweight, reliable, open source, and easy to setup and use.

Open Source Web Development Tutorials - Dev Shed

Open Source Web Development Tutorials - Dev Shed Open Source Programming Resources

IBM developerWorks : Open source tutorials and projects

Find how-to information, tools, and project updates to help you develop with open source technologies and use them with IBM's products. Topic areas include Eclipse, Globus/grid, Apache, Derby/Cloudscape, Linux, scripting languages like PHP, Perl, and Python, as well as broader discussions about licensing and open source development.

The H: Open Source, Security and Development

The H brings you the in-depth coverage of the world of IT, communications, data security and the politics of technology.

Open Source Matters

Joomla! - the dynamic portal engine and content management system

Community driven open source middleware

e107 - Free CMS Open Source Content Management System

e107 is a free (open-source) content management system allowing you to easily manage and publish your content. Developers can save time in building websites and powerful online applications. Users can avoid programming completely! Its simple installation wizard will have you up and running in 5 minutes!

Pligg CMS Open Source Content Management System

Pligg CMS provides free software to create your own social networking website. Start a site in minutes using Pligg Content Management System and save time and money on your next website.