| C# / CSharp Open Source |
| Ajax |
| Google Map Net Control | jsc |
| Aspect Oriented Frameworks |
| AspectDNG | AspectSharp | DotNetAOP | Encase | NAop | NKalore Compiler |
| PostSharp | Runtime Assembly Instrumentation Library | SetPoint |
| Bloggers |
| BlogEngine.NET | dasBlog | Dot Text | SubText | tBlogger | TriptychBlog |
| Build Systems |
| BuildStudio | BusyBeeBuilder | Byldan | CruiseControl.NET | DevBuildRunner | Draco.NET |
| eAnt | NAnt | NAntContrib | NAntRunner | NET Pre Build | NETZ |
| Business Application |
| BurnOut | Chaos files extractor | DC | IsoCreator | iTunes | MonoCalendar |
| Quartz Enterprise Scheduler | Tea Timer for Windows | Timetabler |
| Charting Reporting Tools |
| DaveChart | EasyDiagram | fyiReporting | googlechartsharp | NChart | NET Charts |
| NPlot | SkyNET | XSCharting | ZedGraph |
| Chat Servers |
| Dot Net Chat server | IRCmmm | Thresher |
| Code Coverage Tools |
| NCover | NCover GotDotNet | NCoverCop | PartCover |
| Content Management Systems CMS |
| Amplefile | Cube CMS | Cuyahoga | DocLib | DotNetNuke | Go.Kryo |
| JMDCMS | Kodai CMS | mojoPortal | N2 | nkCMS | Rainbow |
| umbraco | VWD CMS | XMLNuke |
| CRM ERP |
| BlueWhaleCRM | ICPAC | Tustena CRM |
| Database |
| Berkeley DB | Data Access Objects | Data Tier Generator | DB Web Admin | MySQLDriverCS | NBearLite |
| SQL Power Injector | TDO |
| Development |
| AIMLBot | AODL | Asterisk | Be.HexEditor | Castle | Circle Dock |
| Command Line Option Parsing | devAdvantage | Dotnet IL Editor | DotNetLib | EnvMan | Exocortex |
| Foley | Gaia Ajax | HessianC | IKVM | Jayrock | JSON NET |
| LitJSON | MMC | NDoc | NExcel | Nini | Paladin RAD Framework |
| ScintillaNET | SerialPort | sfv.net | Sinergia | Spring.NET | SubSonic |
| ThreadMessaging | Thycotic.Web.RemoteScripting | TULP2G | Utilities | Vici Parser | Vici WinService |
| Wangdera |
| DotNetOpenMail | SharpWebMail |
| Forum |
| dnfBB | YetAnotherForum |
| Game |
| Axiom 3D Engine | Brume | DirectShow | DotNETris | Killer Instinct | Media File XStream |
| MeWiG | PokDTC | PurpleSharp | RealmForge | SDL | SokoSolve Sokoban |
| Space Trader |
| GIS |
| Geotools.Net | MsSqlSpatial | NetTopologySuite | Proj.NET | SharpMap |
| GUI |
| CsGL | DockPanel | FOP | Gimp | Gtk | SharpVectorGraphics |
| SourceGrid | SwfDotNet | TreeViewAdv | wx NET |
| IDEs |
| CSharp Studio | MonoDevelop | SharpDevelop | Software Studio | xacc.ide |
| Installers Generators |
| NInstall | WiX |
| Inversion of Control Dependency Injection |
| Autofac | Castle | ObjectBuilder | Spring.net | StructureMap | Winter.NET |
| Issue Tracking |
| BTsys | BugBye | Buglog | BugNet | BugTracker.NET |
| Logging Tools |
| AppLog | Common.Logging | CSharp Dot Net Logger | CSharp Logger | log4net | Logger.NET |
| LogThis | LogZipper.NET | NLog | TraceTool |
| Mobile |
| mSeller |
| Network Clients |
| Alchemi | CxBrowser | DICOM | Dot Net FTP Client | Dot Net Telnet | DotNetControlExtender |
| edtFTPnet | fileSync | Fluent.Toc | FreeMeter | FTP class | Ftp Dot Net |
| Ftp4net | GibPhone | Granados | GROF | iCalendar | IceChat |
| IZWebFileManager | Jabber Net | lphant | Metro | MonoTorrent | MSNP Helper API |
| NagMIN | NC Net | NET LOGGER | net policy | Net Statistics | NetAr |
| NetSpell | Newsreader | NGrid | nHapi | OpenPOP.NET | OpenSmtp.net |
| RemoteCalendars | SharpDownload | SharpPcap | SharpPrivacyLibrary | SharpSSH | SharpWebMail |
| SmartIrc4net | Smilla .NET | SNMP Observer | TBDEV | Telnet Class Library | VNC Client |
| Windows TFTP Utility | Woofy |
| Network Servers |
| CSharp Email Server | FTP.NET | NeatUpload | netBPM | NMail | WebDAV.NET Server |
| ASP.NET FO PDF | iTextSharp | PDF Clown | PDFjet | PDFsharp | Report.NET |
| SharpPDF |
| Persistence Frameworks |
| Advanced Data Provider | BATIS.NET | BBADataObject | csopf | D4Modelizer | Data Holder |
| FileHelpers Library | Gentle.NET | Habanero | iBATIS.NET | N ORCA | NDal |
| NEO | NHibernate | NPersist | ObjectBroker | ODX | OJB.NET |
| OPF.Net | OR.NET | ORM.NET | Ormyx | Persist.NET | Sisyphus Persistence Framework |
| Sooda | Thycotic.Data | TinyPersistence | Ubik | Vici CoolStorage | XPrevail |
| Portals |
| Media Portal | My Community Portal | OmniPortal | Personal .NET Portal |
| Profilers |
| NProf | NProfiler | Prof It |
| Project Management |
| Personal Task Manager | SharpForge | User Story.NET |
| RSS RDF |
| Aggie | Atom.NET | FeedExpress | GtkSharpRSS | iPodder | mail2rss |
| NRss | RSS Bandit | RSS Feeder | RSS.NET |
| Rule Engines |
| Drools.NET | NxBRE | SRE |
| Search Engines |
| dotLucene | Lucene.Net | NLucene | openDICOM |
| Sound Audio |
| OpenSebJ | SharpFFmpeg | Text2Speech |
| Source Control |
| DotSVN | NetCvsLib | Porc | Sharpcvslib |
| SQL Clients |
| Database Commander | SQL Buddy |
| Template Engines |
| Evolve MasterPages | iCodeGenerator | Netro | netTiers | NVelocity | StringTemplate.NET |
| Testing |
| csUnit | Dot NetUnit | dotunit | EasyMock.NET | MbUnit | MockObjects |
| Nester | NETUnit | NUnit | NUnitAsp | NUnitForms | Rhino.Mocks |
| SystiN | TestDriven | VSNUnit | XT Unit | Zanebug |
| UML |
| MonoUML |
| Web Frameworks |
| Creuna Platform | Ingenious MVC | Maverick.NET | MaverickLite | MonoRail | NStruts |
| Vici | Visual WebGui | Websharp |
| Web Service |
| MantisConnect |
| Web Testing |
| IeUnit web testing framework | NUnitAsp | WatiN | WET |
| Wiki Engines |
| DevHawk Wiki | FlexWiki | LiteWiki | Perspective | Perspective Wiki Engine | ProntoWiki |
| ScrewTurn Wiki | SushiWiki | Thufir |
| Workflows |
| NetBpm | NServiceBus |
| XML Parsers |
| DINAMIC XML Editor | MyXaml | NDigester | SAX for NET | SAX.NET |