1. Zenoss (http://www.zenoss.com/)
Zenoss is an open source IT Management suite. You can observe and monitor your entire network using Zenoss. It consists of an alert console, network discovery, performance monitoring, service monitoring and inventory modules. It is enterprise-ready, free, easy to install and maintain, and modular through ZenPacks.
2. Mono (http://www.mono-project.com/)
Mono is the open source implementation of Microsoft's .NET technologies. this technology combines two incompatible worlds (*nix and Microsoft) into a single agile, open source and stable realm. Mono allows you to develop powerful and advanced server-side applications on Linux, Mac OS X and Windows.
3. Apache (http://www.apache.org/)
The Apache Web Server is the Internet's most popular Web server.Apache is a freely available Web server that is distributed under an "open source" license. Version 2.0 runs on most UNIX-based operating systems (such as Linux, Solaris, Digital UNIX, and AIX), on other UNIX/POSIX-derived systems (such as Rhapsody, BeOS, and BS2000/OSD), on AmigaOS, and on Windows 2000. According to a Netcraft (www.netcraft.com) Web server survey 60% of all Web sites on the Internet are using Apache (62% including Apache derivatives), making Apache more widely used than all other Web servers combined.
4. SugarCRM (http://www.sugarcrm.com/)
SugarCRM produces the web application Sugar, a customer relationship management (CRM) system that is available in both open-source and commercial open-source applications.SugarCRM originated on the LAMP stack of Linux, Apache, MySQL and PHP, but also runs on other operating systems and platforms that can deliver PHP (such as Windows, Solaris and Mac OS X). SugarCRM can also use Microsoft's Internet Information Server (IIS) as a web server, and Microsoft SQL or Oracle as alternative databases.
5. Drupal (https://www.drupal.org/)
Content management systems (CMSs) provide a collaborative environment for social networking sites, corporate Web sites, intranets, community portals, e-commerce applications and discussion sites. Drupal is a CMS that allows communities to publish, share and manage a variety of content on a Web server. Communities range from a few users to tens of thousands. Drupal is modular and has dozens of add-ons that enhance its functionality and appeal, such as blogs, forums, newsletters, podcasting, photos, file uploading and downloading, collaborative authoring and e-commerce.
6. OpenSolaris (https://solaris.java.net/)
OpenSolaris is the x86 version of Sun's Solaris operating system. The two most exciting aspects of this operating system are that it runs on inexpensive x86 hardware and it contains all of the built-in enterprise components (virtualization and ZFS) as the standard Solaris offering. OpenSolaris delivers next-generation computing technology, commercial support and a worldwide development community.
7. MySQL (https://www.mysql.com/)
MySQL, now owned by Oracle, is the world's most popular open source database software. It's available for almost any operating system, and it is drag-and-drop-capable with no modifications from one platform to another. MySQL powers business applications, Internet sites and enterprise tools, such as Zenoss. It competes with the most-expensive commercial relational database systems.
8. Pentaho (http://www.pentaho.com/)
Pentaho is a commercial company that offers a community edition of its open source business intelligence product as free to use, explore and change at will. Both editions have query, reporting, interactive analysis, dashboards, data integration and data mining.
9. Magento (http://magento.com/)
Magento eCommerce suite (the Community Edition) offers a free and open source. The Magento Enterprise Edition is also open source, but it carries a commercial license for advanced support and functionality. The Community Edition offers full e-commerce capabilities, such as catalog browsing, marketing tools, analytics and reporting, search engine optimization, mobile commerce, checkout, shipping and customer service modules.
10. Java (https://www.java.com/en/)
Java technologies have powered enterprise applications since 1995. Java currently powers more than 800 million PCs, 2 billion handheld devices and 3.5 billion smart cards as well as a host of set-top boxes, Web cams, games, medical devices and much more. With uptake by major companies such as Oracle (Java's new owner) and IBM, Java is a technology to watch and embrace for all levels of enterprise use.