Browse free open source C# Libraries and projects below. Use the toggles on the left to filter open source C# Libraries by OS, license, language, programming language, and project status.

  • Papirfly: Best user-friendly DAM and Content Creation Software Icon
    Papirfly: Best user-friendly DAM and Content Creation Software

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  • 1
    Spectre.Console

    Spectre.Console

    Library that makes it easier to create beautiful console applications

    Spectre.Console is a .NET library that enables the creation of rich, cross‑platform console applications. Heavily inspired by Python’s Rich library, it provides advanced styling, layout, and input capabilities for modern terminal UIs. Supports tables, grids, panels, and a Rich inspired markup language. Supports the most common SRG parameters when it comes to text styling such as bold, dim, italic, underline, strikethrough, and blinking text. Supports 3/4/8/24-bit colors in the terminal. The library will detect the capabilities of the current terminal and downgrade colors as needed. Written with unit testing in mind.
    Downloads: 3 This Week
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  • 2
    This project consists of a linux kernel driver and some user-mode libraries. They allow a process to create a virtual usb host controller. Real or virtual usb devices can be "plugged" into this controller.
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    Downloads: 70 This Week
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  • 3
    C# Algorithms

    C# Algorithms

    Plug-and-play class-library project of standard data structures

    A plug-and-play class-library project of standard Data Structures and Algorithms, written in C#. It contains 75+ Data Structures and Algorithms, designed as Object-Oriented isolated components. Even though this project started for educational purposes, the implemented Data Structures and Algorithms are standard, efficient, stable and tested. This is a C#.NET solution-project, and it contains three subprojects. Algorithms, a class library project which contains the Algorithms implementations. Data Structures, a class library project which contains the Data Structures implementations. Also, UnitTest, a unit-testing project for the Algorithms and Data Structures.
    Downloads: 2 This Week
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  • 4
    ClashN

    ClashN

    A clash client for Windows, support Mihomo

    clashN is a Windows desktop client for the Clash networking engine, providing a graphical interface to manage proxies, rules, and profiles. It wraps the Clash core in a familiar, configurable UI so users can import subscriptions, switch nodes, and observe connections without editing YAML by hand. The app emphasizes rule-based routing, letting you combine rule providers and policy groups to steer traffic by domain, process, or destination category. System-wide proxy control, including PAC and TUN/TAP options, helps route applications that don’t natively support proxies. Logs, traffic charts, and connection inspectors make troubleshooting and optimization straightforward. For power users, granular profile editing and hot-reloading reduce the friction of iterating on configurations.
    Downloads: 2 This Week
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  • EasySend is a no-code platform that transforms customer journeys Icon
    EasySend is a no-code platform that transforms customer journeys

    Defy form limits. 
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  • 5
    CppSharp

    CppSharp

    Tools and libraries to glue C/C++ APIs to high-level languages

    CppSharp is a tool and set of libraries that facilitates the usage of native C/C++ code with the .NET ecosystem. It consumes C/C++ header and library files and generates the necessary glue code to surface the native API as a managed API. Such an API can be used to consume an existing native library in your managed code or add managed scripting support to a native codebase. The supported target languages at present are C# and C++/CLI. It can also be used as a library to parse native code into a syntax tree with a rich declaration and type information model. Generates the glue binding code from a syntax tree of the native code. Provides APIs for parsing of C/C++ source code into a syntax tree. Mirrors the Clang's C/C++ AST and type system classes in C# APIs.
    Downloads: 2 This Week
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  • 6
    DockPanel Suite

    DockPanel Suite

    The Visual Studio inspired docking library for .NET WinForms

    Microsoft first introduced the docking panel layout in Visual Studio .NET (2002), and soon it became popular in application design. Many commercial .NET component vendors started to provide docking libraries initially, but there was no good free and open source alternative until WeiFen Luo released DockPanel Suite (DPS for short) on SourceForge.net in 2006. After an 18 month hiatus, the project has been resurrected and is now being actively developed on GitHub.
    Downloads: 2 This Week
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  • 7
    Librelancer

    Librelancer

    A re-implementation of Freelancer

    Librelancer is an open-source reimplementation of the engine behind Freelancer, the iconic 2003 space trading and combat simulation game by Microsoft. Written in C# and powered by OpenGL and modern game development practices, Librelancer faithfully replicates the original gameplay while providing a flexible codebase for modding, analysis, and future enhancements. It supports original assets and is designed to be both a preservation project and a foundation for new space simulation games inspired by Freelancer’s legacy.
    Downloads: 2 This Week
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  • 8
    LiteNetLib 1.0 indev

    LiteNetLib 1.0 indev

    Lite reliable UDP library for Mono and .NET

    Lite reliable UDP library for .NET Framework 3.5, Mono, .NET Core 2.0, .NET Standard 2.0. Small packet size overhead (1 byte for unreliable, 3 bytes for reliable packets). Helper classes for sending and reading messages. Always use library sources instead of precompiled DLL files (because there are platform-specific #ifdefs and workarounds for unity bugs). Fast packet serializer (Usage manual). Automatic small packets merging. Automatic fragmentation of reliable packets. Automatic MTU detection. UDP NAT hole punching. NTP time requests. Packet loss and latency simulation. IPv6 support (dual mode). Connection statisitcs (need DEBUG or STATS_ENABLED flag). Multicasting (for discovering hosts in local network). Unity support.
    Downloads: 2 This Week
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  • 9
    MudBlazor

    MudBlazor

    Do more with Blazor, utilizing CSS and keeping Javascript to a minimum

    Trusted by thousands of users, from hobby developers to large enterprises. Use MudBlazor to rapidly build amazing web applications without leaving your loved C# language and toolchain. We bring together everything that's required to build amazing Blazor applications that scale from desktop to mobile. Apart from the library itself we also provide templates, a learning platform, theme manager, demo and example projects as well as an online code editor integrated with our documentation and issue tracking. With more to come. We help companies build amazing apps in record time and let them focus on their business instead of buttons, MudBlazor is battle-tested and one of the fastest-improving platforms, and much more. We started MudBlazor with a simple promise, to empower the developer and fully take advantage of what Blazor offers. With MudBlazor you can create exceptional apps without the burden of mastering HTML, CSS and JS and focus your skillset on C#.
    Downloads: 2 This Week
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  • Software for managing apps and accounts | WebCatalog Icon
    Software for managing apps and accounts | WebCatalog

    Tired of juggling countless browser tabs? WebCatalog Desktop turns your favorite web apps into dedicated desktop apps

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  • 10
    OpenMCDF

    OpenMCDF

    Structured Storage .net component - pure C#

    OpenMCDF is a 100% .net / C# component that allows developers to manipulate Microsoft Compound Document File Format for OLE structured storage. It supports read/write operations on streams and storages and traversal of structures tree. Development and issue tracking has moved to github platform at https://github.com/ironfede/openmcdf
    Downloads: 10 This Week
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  • 11
    Fast Artificial Neural Network Library is a free open source neural network library, which implements multilayer artificial neural networks in C with support for both fully connected and sparsely connected networks. Cross-platform execution in both fixed and floating point are supported. It includes a framework for easy handling of training data sets. It is easy to use, versatile, well documented, and fast. Bindings to more than 15 programming languages are available. An easy to read introduction article and a reference manual accompanies the library with examples and recommendations on how to use the library. Several graphical user interfaces are also available for the library.
    Downloads: 11 This Week
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  • 12
    AngleSharp

    AngleSharp

    The ultimate angle brackets parser library parsing HTML5, MathML, SVG

    AngleSharp follows the W3C specifications and gives you the same results as state of the art browsers. Besides the official API AngleSharp adds some useful extension methods on top. This makes working with the DOM convenient. AngleSharp integrates everything you need to explore and mutate the DOM tree. Node retrieval is straight forward by using powerful CSS query selectors. The CSS queries in AngleSharp are super fast and very simple to use. AngleSharp respects the relationship of HTML with CSS. Therefore CSS is a first class citizen in the AngleSharp eco-system. Nevertheless, it is your choice if you want to use CSS with HTML, CSS alone or if you provide your own CSS solution. AngleSharp offers a lot of extension points. One of the best possibilities is providing scripting engines. This gives you a very elegant way of using JavaScript with C# on webpages. You can even script in other languages if you want to.
    Downloads: 1 This Week
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  • 13
    Async MySQL Connector .NET and .NET Core

    Async MySQL Connector .NET and .NET Core

    Async MySQL Connector for .NET and .NET Core

    This is an ADO.NET data provider for MySQL. It provides implementations of DbConnection, DbCommand, DbDataReader, DbTransaction, the classes needed to query and update databases from managed code. This library implements true asynchronous I/O for database operations, without blocking (or using Task.Run to run synchronous methods on a background thread). This greatly improves the throughput of a web server that performs database operations. This library outperforms MySQL Connector/NET (MySql.Data) on benchmarks. This library is MIT-licensed and may be freely distributed with commercial software. Commercial software that uses Connector/NET may have to purchase a commercial license from Oracle. Fixes dozens of open bugs in Oracle’s Connector/NET; passes all ADO.NET Specification Tests. First MySQL library to support .NET Core; uses the latest .NET features.
    Downloads: 1 This Week
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  • 14
    CameraVoyeur

    CameraVoyeur

    Windows-oriented utility to log frames from a connected camera devices

    CameraVoyeur is a small Windows-oriented utility that demonstrates how to capture, preview, and possibly log frames from a connected camera device in a lightweight way. It’s set up more like an experiment or proof-of-concept than a polished end-user app, focusing on the plumbing for grabbing images from the webcam. The project shows how to access the camera stream, keep it running, and expose the captured output for later use or display. Because it’s in a regular GitHub repo and not a closed binary, you can inspect the code to see how device selection, frame acquisition, and UI/display are wired. This makes it useful for developers who want to add camera capture to a Windows tool or who need a barebones sample to build surveillance, monitoring, or computer vision toys on top of. Its value is really in being a simple, readable reference rather than a big camera suite.
    Downloads: 1 This Week
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  • 15
    ClearScript

    ClearScript

    A library for adding scripting to .NET applications

    ClearScript is a library that makes it easy to add scripting to your .NET applications. It currently supports JavaScript (via V8 and JScript) and VBScript. Simple usage; create a script engine, add your objects and/or types, run scripts. Support for several script engines: Google's V8, Microsoft's JScript and VBScript. Exposed resources require no modification, decoration, or special coding of any kind. Scripts get simple access to most of the features of exposed objects and types. Full support for generic types and methods, including C#-like type inference and explicit type arguments. Exposed .NET collections support native script iteration mechanisms. Scripts can invoke methods with output parameters, optional parameters, and parameter arrays. Support for exposing all the types defined in one or more assemblies in one step. Optional support for importing types and assemblies from script code.
    Downloads: 1 This Week
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  • 16
    CodeQL

    CodeQL

    Libraries and queries that power security researchers

    CodeQL is a semantic code analysis engine that treats programs as queryable databases, enabling users to write expressive queries that identify security vulnerabilities, logic bugs, and code quality issues across large codebases. Instead of just pattern matching text, CodeQL ingests source code, builds rich representations of structure and data flow, and allows queries that reason about control flow, type systems, and interprocedural relationships. This makes it powerful not just for basic linting but for deep detection of complex security flaws like SQL injection, cross-site scripting, and taint propagation that traditional static analyzers can miss. CodeQL is used by security teams, developers, and open-source tooling to create reusable query libraries, enforce policy across repositories, and automate findings in CI/CD pipelines.
    Downloads: 1 This Week
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  • 17
    Dynamic Data

    Dynamic Data

    Reactive collections based on Rx.Net

    Rx is extremely powerful but out of the box provides nothing to assist with managing collections. In most applications, there is a need to update the collections dynamically. Typically a collection is loaded and after the initial load, asynchronous updates are received. The original collection will need to reflect these changes. In simple scenarios the code is simple. However, typical applications are much more complicated and may apply a filter, transform the original dto and apply a sort. Even with these simple everyday operations, the complexity of the code is quickly magnified. Dynamic data has been developed to remove the tedious code of dynamically maintaining collections. It has grown to become functionally very rich with at least 60 collection-based operations which amongst other things enable filtering, sorting, grouping, joining different sources, transforms, binding, pagination, data virtualization, expiration, disposal management plus more.
    Downloads: 1 This Week
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  • 18
    Elsa Workflows

    Elsa Workflows

    A .NET Standard 2.0 Workflows Library

    Build workflows in code using the Workflow Builder API or as data using JSON syntax. Or use the workflow designer to design executable workflows visually. Elsa comes with a reusable dashboard component to manage workflows and activities. Run workflows from within your application using simple to use APIs. Start or resume workflows manually, or automatically by invoking triggers. Make it your own by extending the set of activities with your own. Implementing custom activities allows for powerful workflows that can be implemented with ease. Workflows can be defined using plain C# code. In addition to an increasing number of activities that you can choose from, Elsa is designed to be extensible with your own custom activities. Short-running Workflows can be useful to implement a business rules engine, while long-running workflows greatly simplify the implementation of complex processes that involve coordinating between multiple agents (users & machines).
    Downloads: 1 This Week
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  • 19
    MQTTnet

    MQTTnet

    High performance .NET library for MQTT based communication

    MQTTnet is a high-performance .NET library for MQTT-based communication. It provides an MQTT client and an MQTT server (broker) and supports the MQTT protocol up to version 5. TLS support for client and server (but not UWP servers). Extensible communication channels (e.g. In-Memory, TCP, TCP+TLS, WS). Lightweight (only the low-level implementation of MQTT, no overhead). Performance optimized (processing ~150.000 messages/second). Uniform API across all supported versions of the MQTT protocol. Tested on the local machine (Intel i7 8700K) with MQTTnet client and server running in the same process using the TCP channel. The app for verification is part of this repository and stored in /Tests/MQTTnet.TestApp.NetCore. List of connected clients available. Supports connected clients with different protocol versions at the same time. Able to publish its own messages (no loopback client required). Able to receive every message (no loopback client required).
    Downloads: 1 This Week
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  • 20
    NSubstitute

    NSubstitute

    A friendly substitute for .NET mocking libraries

    NSubstitute is designed for Arrange-Act-Assert (AAA) testing, so you just need to arrange how it should work, then assert it received the calls you expected once you're done. Because you've got more important code to write than whether you need a mock or a stub. It is an attempt to satisfy our craving for a mocking library with a succinct syntax that helps us keep the focus on the intention of our tests, rather than on the configuration of our test doubles. We've tried to make the most frequently required operations obvious and easy to use, keeping less usual scenarios discoverable and accessible, and all the while maintaining as much natural language as possible. There are already some great mocking libraries around for .NET, so why create another? We found that for all their great features, none of the existing libraries had the succinct syntax we were craving — the code required to configure test doubles quickly obscured the intention behind our tests.
    Downloads: 1 This Week
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  • 21
    NetTopologySuite

    NetTopologySuite

    A .NET GIS solution that is fast and reliable for the .NET platform.

    A .NET GIS solution that is fast and reliable for the .NET platform. NetTopologySuite is a direct port of all the functionalities offered by JTS Topology Suite: NTS exposes JTS in a '.NET way', for example using Properties, Indexers, etc. The JTS Topology Suite is an API for modeling and manipulating 2-dimensional linear geometry. It provides numerous geometric predicates and functions. JTS conforms to the Simple Features Specification for SQL published by the Open GIS Consortium.
    Downloads: 1 This Week
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  • 22
    Pidgin

    Pidgin

    A lightweight and fast parsing library for C#

    Pidgin is a lightweight and fast parser combinator library for C#. It allows developers to construct parsers using a declarative approach, facilitating the creation of complex parsers without external tools.​
    Downloads: 1 This Week
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  • 23
    Stripe.net

    Stripe.net

    Stripe.net is a sync/async .NET 4.6.1+ client

    A .NET library to facilitate Stripe payment integration, supporting a full range of payment and subscription features for .NET applications.
    Downloads: 1 This Week
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  • 24
    Windows UI Library

    Windows UI Library

    Windows 10 native controls and Fluent styles for your applications

    WinUI is a user interface layer that contains modern controls and styles for building Windows apps. As the native UI layer in Windows it embodies Fluent Design, giving each Windows app the polished feel that customers expect. WinUI 2 is a library of controls that provides official native Microsoft UI controls and features for Windows UWP apps. WinUI 2 can be used in any Windows 10 UWP XAML app, or in a Xamarin.Forms app running on Windows 10 using native view embedding. WinUI 3 is the next generation of the WinUI framework. It dramatically expands WinUI into a full UX framework, making WinUI available for all types of Windows apps, from Win32 to UWP, for use as the UI layer. You can build new Windows apps using WinUI 3, which ships as a part of the Windows App SDK. The latest available stable release is the Windows App SDK 0.8 (previously called Project Reunion). With this release, you can ship production Desktop apps to the Microsoft Store.
    Downloads: 1 This Week
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  • 25
    YoutubeExplode

    YoutubeExplode

    Abstraction layer over YouTube's internal API

    YoutubeExplode is a .NET library that provides a high-level abstraction for interacting with YouTube data, enabling developers to retrieve metadata and download media streams programmatically. The project exposes a clean API that allows applications to query videos, playlists, channels, and search results without relying on the official YouTube Data API. Under the hood, the library parses raw page data and leverages reverse-engineered internal endpoints to obtain structured information and stream manifests. Developers can use it to access details such as titles, authors, durations, captions, and available media formats, as well as to download audio or video streams for further processing. The library is designed to be intuitive and cross-platform through .NET Standard compatibility, making it suitable for desktop tools, automation pipelines, and media utilities.
    Downloads: 1 This Week
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