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Top 23 C# Open-Source Projects
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Shout out to @MrSimmo and @Zardoz8901 from this issue on github! Do read the issue for more context.
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Project mention: My PC Cries Every Morning, But These 8 Startup Apps Are Worth It | dev.to | 2025-11-12
Files: File Explorer's Cooler, Younger Sibling
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ShareX
ShareX is a free and open-source application that enables users to capture or record any area of their screen with a single keystroke. It also supports uploading images, text, and various file types to a wide range of destinations.
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Avalonia
Develop Desktop, Embedded, Mobile and WebAssembly apps with C# and XAML. The future of .NET UI
> I like WASM and I want to like WASM but the rate of maturity within the ecosystem is incredibly abysmal.
The C# toolchain for WebAssembly is pretty good. You can do a lot with Avalonia and Uno:
https://avaloniaui.net/
https://platform.uno/
Here's a C# clone of Visual Basic compiled to WebAssembly:
https://bandysc.github.io/AvaloniaVisualBasic6/
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It's probably very hardware dependent now, just like it was back then. My calculator opens to interactive in much less than 1 second, but I've got a 9800x3d and fast memory and nvme drive. The other guy saying his start menu takes 8 seconds to open probably has a pretty shit computer.
I definitely got the stupid hourglass in win 95 when trying to open anything, but my understanding of computers at the time was that black ones were faster than beige ones, so my computer was probably shit.
I tried to look up calculator win 95 vids on YouTube, there are a couple. One gets an hourglass - but less than a second, one is instant, one shows the calculator crashing lol.
During this I also found out that Microsoft Calculator is open source: https://github.com/microsoft/calculator
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SaaSHub
SaaSHub - Software Alternatives and Reviews. SaaSHub helps you find the best software and product alternatives
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Project mention: Pulumi Has a Free API: Infrastructure as Code with Real Programming Languages | dev.to | 2026-03-28
Pulumi lets you define cloud infrastructure using real programming languages — TypeScript, Python, Go, C#, Java — instead of YAML or HCL. You get loops, conditionals, functions, type checking, and IDE autocomplete for your infrastructure.
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WaveFunctionCollapse
Bitmap & tilemap generation from a single example with the help of ideas from quantum mechanics
Project mention: Bitmap and tilemap generation from a single example | news.ycombinator.com | 2026-04-30 -
Project mention: .NET 10 Preview 6 brings JIT improvements, one-shot tool execution | news.ycombinator.com | 2025-07-30
https://github.com/quozd/awesome-dotnet
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awesome-dotnet-core
:honeybee: A collection of awesome .NET core libraries, tools, frameworks and software
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Roslyn
The Roslyn .NET compiler provides C# and Visual Basic languages with rich code analysis APIs.
Project mention: I'm writing a history of Visual Basic, Chapter 1 is up | news.ycombinator.com | 2026-05-11VB.NET is open source, supports AOT, and there is little else that VB 6 does better, other than COM integration, which .NET was always a bit lower level
https://github.com/dotnet/roslyn
Now I bet what you mean is the graphical part, and yes that is only partial open source.
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Project mention: NodeWarden: Bitwarden on Cloudflare Workers — No Server Required | dev.to | 2026-04-07
Bitwarden Official Website
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lively
Free and open-source software that allows users to set animated desktop wallpapers and screensavers powered by WinUI 3.
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ANTLR
ANTLR (ANother Tool for Language Recognition) is a powerful parser generator for reading, processing, executing, or translating structured text or binary files.
Project mention: RCParsing VS ANTLR - a user suggested alternative | libhunt.com/r/RCParsing | 2025-09-19ANTLR is a lexer-based, powerful tool for creating own DSL and analyzing them. But it's and overkill for simple languages (JSON, for example), while RCParsing is good for both complex and simple languages, allows you to choose: work with AST or immediately calculate value while parsing.
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CleanArchitecture
Clean Architecture Solution Template: A proven Clean Architecture Template for ASP.NET Core 10 (by ardalis)
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OpenRA
Open Source real-time strategy game engine for early Westwood games such as Command & Conquer: Red Alert written in C# using SDL and OpenGL. Runs on Windows, Linux, *BSD and Mac OS X.
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mcp-for-beginners
This open-source curriculum introduces the fundamentals of Model Context Protocol (MCP) through real-world, cross-language examples in .NET, Java, TypeScript, JavaScript, Rust and Python. Designed for developers, it focuses on practical techniques for building modular, scalable, and secure AI workflows from session setup to service orchestration.
Project mention: Host Your Node.js MCP Server on Azure Functions in 3 Simple Steps | dev.to | 2025-12-09🚨 Free course alert! If you're new to MCP, check out the MCP for Beginners course to get up to speed quickly.
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amplication
Amplication brings order to the chaos of large-scale software development by creating Golden Paths for developers - streamlined workflows that drive consistency, enable high-quality code practices, simplify onboarding, and accelerate standardized delivery across teams.
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guiadevbrasil
Um guia extenso de informações com um vasto conteúdo de várias áreas para ajudar, agregar conhecimento e retirar dúvidas, nesse guia você encontrará tudo que necessário para qualquer carreira relacionada a tecnologia.
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ABP
Open-source web application framework for ASP.NET Core! Offers an opinionated architecture to build enterprise software solutions with best practices on top of the .NET. Provides the fundamental infrastructure, cross-cutting-concern implementations, startup templates, application modules, UI themes, tooling and documentation.
Project mention: We migrated a .NET app from ABP Framework to Granit without downtime - here's the playbook | dev.to | 2026-05-21We just finished moving a 15-module .NET service from ABP Framework to Granit — without a maintenance window, without a code freeze, and without a parallel run-everything-twice phase. The whole thing took about ten weeks running alongside feature work.
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SaaSHub
SaaSHub - Software Alternatives and Reviews. SaaSHub helps you find the best software and product alternatives
NOTE:
The open source projects on this list are ordered by number of github stars.
The number of mentions indicates repo mentiontions in the last 12 Months or
since we started tracking (Dec 2020).
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Index
What are some of the best open-source C# projects? This list will help you:
| # | Project | Stars |
|---|---|---|
| 1 | Jellyfin | 54,098 |
| 2 | Files | 44,132 |
| 3 | ShareX | 38,410 |
| 4 | DevToys | 31,730 |
| 5 | Avalonia | 31,104 |
| 6 | calculator | 30,985 |
| 7 | SteamTools | 26,109 |
| 8 | Pulumi | 25,415 |
| 9 | WaveFunctionCollapse | 25,179 |
| 10 | awesome-dotnet | 21,463 |
| 11 | awesome-dotnet-core | 21,314 |
| 12 | Roslyn | 20,519 |
| 13 | PEASS-ng | 20,091 |
| 14 | AspNetCore-Developer-Roadmap | 19,619 |
| 15 | Bitwarden | 19,340 |
| 16 | lively | 19,164 |
| 17 | ANTLR | 18,943 |
| 18 | CleanArchitecture | 18,326 |
| 19 | OpenRA | 17,041 |
| 20 | mcp-for-beginners | 16,677 |
| 21 | amplication | 16,015 |
| 22 | guiadevbrasil | 15,732 |
| 23 | ABP | 14,348 |
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ReSharper brings a professional toolset for C# developers backed by over 20 years of experience, enterprise-grade security, SOC 2 compliance, and the trust of companies worldwide.
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