44. Joomla Replaces: Sitecore CMS, Kentico
Powering 2.7 percent of all sites on the internet, Joomla claims to be "the world’s most popular open source CMS." Many e-commerce sites use Joomla, and more than 200 e-commerce add-ons are available. Operating System: OS Independent
45. Magnolia Replaces: SharePoint, Sitecore CMS, Kentico
Used by numerous Fortune 500 companies and government entities, Magnolia is an enterprise-grade content management system that "runs thousands of mission-critical websites." In addition to the free community version, it also comes in a paid enterprise edition. Operating System: Windows, Linux
46. WebGUI Replaces: Sitecore CMS, Kentico
Unlike many of the other open-source content management systems, this "all-in-one CMS" includes a shopping cart and an integrated payment gateway as part of the core software. The website includes a tremendous amount of documentation and help for those just getting started. Operating System: Windows, Linux/Unix, OS X
47. XOOPS Replaces: Sitecore CMS, Kentico
XOOPS is a modularized, database-driven content management system and Web application development platform. It currently has 20 e-commerce modules, as well as other tools for helping you build your online store. Operating System: OS Independent
Databases
48. Firebird Replaces: Microsoft SQL Server Standard
First created in 1981, this RDBMS boasts "excellent concurrency, high performance, and powerful language support for stored procedures and triggers." Professional support is available through several of the companies that support the Firebird Foundation. Operating System: Windows, Linux, Unix, OS X, Solaris
49. MySQL Replaces: Microsoft SQL Server Standard
Many of the open source e-commerce solutions on our list require the MySQL database in order to function. It comes in both a free edition and paid editions which are supported by Oracle. Operating System: Windows, Linux, OS X
50. PostgreSQL Replaces: Microsoft SQL Server Standard
Another good option for storing your e-commerce data, PostgreSQL claims to be "the world's most advanced open source database." Commercial support and hosting are available through third-party providers. Operating System: Windows, Linux, OS X
Web Page Editors
51. Amaya Replaces: Adobe Dreamweaver, Microsoft Expression Studio Web Professional
Created by the World Wide Web Consortium (W3C), Amaya is both a browser and a Web page editor. It supports HTML, CSS, XML, XHTML, MathML and SVG. Operating System: Windows, Linux, OS X
52. BlueGriffon Replaces: Adobe Dreamweaver, Microsoft Expression Studio Web Professional
Launched in 2011, this replacement for the older NVU open source Web editor is powered by Gecko, the engine that runs Mozilla's Firefox. It offers an intuitive WYSIWYG interface that's helpful for those who are new to Web design. The basic software is free, but several add-ons do require a fee. Operating System: Windows, Linux, OS X
53. KompoZer Replaces: Adobe Dreamweaver, Microsoft Expression Studio Web Professional
Another NVU derivative, KompoZer aims to make it easy for newbies to create professional-looking websites. The interface is very similar to Dreamweaver, and it offers a tabbed display, an integrated FTP site manager, a CSS editor, easy forms and more. Operating System: Windows, Linux, OS X
54. SeaMonkey Replaces: Adobe Dreamweaver, Microsoft Expression Studio Web Professional
This all-in-one tool includes a browser, e-mail client, feedreader, HTML editor, chat client and Web development tools. It's more suitable for advanced users who are comfortable writing code. Operating System: Windows, Linux