- Open Source Aspect-Oriented Frameworks in C
- Open Source Bloggers in C
- Open Source Build Systems in C
- Open Source Charting Reporting Tools in C
- Open Source Chat Servers in C
- Open Source Content Management Systems CMS in C
- Open Source Code Coverage Tools in C
- Open Source Forum Software in C
- Open Source IDEs in C
- Open Source Installers Generators in C
- Open Source Inversion of Control Containers in C
- Open Source Issue Tracking Software in C
- Open Source Logging Tools in C
- Open Source Network Clients in C
- Open Source Network Servers in C
- Open Source PDF Libraries in C
- Open Source Persistence Frameworks in C
- Open Source Portals in C
- Open Source Profilers in C
- Open Source Project Management Tools in C
- Open Source RSS RDF Tools in C
- Open Source Rule Engines in C
- Open Source Search Engines in C
- Source Control Tools in C
- Open Source SQL Clients in C
- Open Source Template Engines in C
- Open Source Testing Tools in C
- Open Source Web Frameworks in C
- Open Source Web Mail Clients in C
- Open Source Web Testing Tools in C
- Open Source Wiki Engines in C
- Open Source XML Parsers in C
- AspectSharp - Aspect# (pronunced as AspectSharp) is a free AOP ( Aspect Oriented Programming ) framework for the .NET Framework, it uses Dynamic Proxies and XML configuration files as basis.
- tBlogger - tBlogger provides a complete blog site written in C# with ASP.NET that uses XML as a backend.
- NAnt - NAnt is a Ant like build tool for .NET
- NChart - NChart provides a wealth of 2D charting for use in business, in education and at home.
- ndCMS - ndCMS is a content management system written in C# that features a user manager, file manager, a WYSIWYG editor and built-in http compression (for those who are not running at least IIS 6 and/or don't have access to modify your IIS settings directly and/or those who don't want to spend a small fortune on a third party HTTP Compressor). The goal of ndCMS is to provide a quick and easy way to deploy a .net website while saving you time and money.
- NCover - A test code coverage tool for C# .NET
- YetAnotherForum - Yet Another Forum.net is a opensource discussion forum or bulletin board system for web sites running ASP.NET. It is ASP.NET based with a MS SQL backend database.
- SharpDevelop - #develop (short for SharpDevelop) is a free IDE for C# and VB.NET projects on Microsoft's .NET platform.
- NInstall - A project to produce an open source package that can compete with the commercial installer products
- StructureMap - StructureMap is a lightweight Inversion of Control (IoC) Container written in C# for .NET development. StructureMap can improve the architectural qualities of an object oriented .NET system by reducing the mechanical costs of good design techniques.
- BugBye - BugBye is a web-based bugtracking system developed using ASP.NET technology and C# as scripting language
- log4net - log4net is a tool to help the programmer output log statements to a variety of output targets. log4net is a port of the excellent log4j framework to the .NET runtime.
- OpenSmtp.net - OpenSmtp.net is an open source SMTP component written in C#
- CSharp Email Server - The C# Mail Server is a C# port of the Java Email Server (JES). JES is an established email server targeted at small centrally maintained installations.
- iTextSharp - iTextSharp is a library that allows you to generate PDF files on the fly.
- OJB.NET - OJB.NET is an object-to-relational persistence tool for the .NET platform.
- OmniPortal - OmniPortal was built on the idea of having a web-portal-kernel, that could handle security, themeing, and localization.
- User Story.NET - This project is a tool for Extreme Programming projects in their User Story tracking.
- RSS Bandit - A desktop news aggregator written in C#
- NxBRE - NxBRE is the first open-source rule engine for the .NET platform and a lightweight Business Rules Engine (aka Rule-Based Engine)
- Lucene.Net - Lucene.Net is a complete up to date .NET port of Jackarta Lucene
- NetCvsLib - NetCvsLib is a CVS client written entirely in C# for the .NET platform. It is implemented as an assembly, and thus can easily be incorporated into other projects.
- Database Commander - Database Commander is a database manager with user-friendly interface for Windows operation system.
- NVelocity - NVelocity is a .Net-based template engine. It permits anyone to use the simple yet powerful template language to reference objects defined in .Net code.
- NUnit - NUnit is a unit-testing framework for all .Net languages. Initially ported from JUnit
- Maverick.NET - Maverick.NET is a .NET port of Maverick, a Model-View-Controller (aka "Model 2") framework for web publishing. It is a minimalist framework which focuses solely on MVC logic, allowing you to generate presentation using a variety of templating and transformation technologies.
- SharpWebMail - SharpWebMail is an ASP.NET Web Mail application that is written in C#. It uses a POP3 server as the mailstore and sends mail through a SMTP. It is very simple to configure (Only a few settings in the web.config file). You can compose HTML messages, search your inbox, read complex mime messages and much more.
- NUnitAsp - NUnitAsp is a tool for automatically testing ASP.NET web pages. It's an extension to NUnit
- SushiWiki - SushiWiki is a WikiWikiWeb like Web application written in C#
- SAX.NET - SAX dot NET is a C# port of the original Java based SAX API specifications.