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.

  • Inventory and Order Management Software for Multichannel Sellers Icon
    Inventory and Order Management Software for Multichannel Sellers

    Avoid stockouts, overselling, and losing control as your business grows.

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  • Network Management Software and Tools for Businesses and Organizations | Auvik Networks Icon
    Network Management Software and Tools for Businesses and Organizations | Auvik Networks

    Mapping, inventory, config backup, and more.

    Reduce IT headaches and save time with a proven solution for automated network discovery, documentation, and performance monitoring. Choose Auvik because you'll see value in minutes, and stay with us to improve your IT for years to come.
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  • 1
    Enums.NET

    Enums.NET

    Enums.NET is a high-performance type-safe .NET enum utility library

    Enums.NET is a high-performance type-safe .NET enum utility library that provides many operations as convenient extension methods. It is compatible with .NET Framework 4.5+ and .NET Standard 1.0+. To help you migrate your code to using the new methods I have created the C# roslyn analyzer Enums.NET.Analyzer which provides a code fix to migrate your usage of the non-generic and unsafe methods to the new methods.
    Downloads: 6 This Week
    Last Update:
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  • 2
    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: 6 This Week
    Last Update:
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  • 3
    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: 6 This Week
    Last Update:
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  • 4
    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: 6 This Week
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  • Data management solutions for confident marketing Icon
    Data management solutions for confident marketing

    For companies wanting a complete Data Management solution that is native to Salesforce

    Verify, deduplicate, manipulate, and assign records automatically to keep your CRM data accurate, complete, and ready for business.
    Learn More
  • 5
    prometheus-net

    prometheus-net

    .NET library to instrument your code with Prometheus metrics

    This is a .NET library for instrumenting your applications and exporting metrics to Prometheus.
    Downloads: 6 This Week
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  • 6
    AWS Lambda for .NET

    AWS Lambda for .NET

    Libraries, samples and tools to help .NET Core developers

    AWS Lambda for .NET is the repository that houses tools, libraries and templates to build and deploy AWS Lambda functions using the .NET ecosystem (including .NET Core and .NET 7+). It provides NuGet packages for event models (e.g., API Gateway, DynamoDB, S3), utilities such as Amazon.Lambda.Tools for CLI deployment, and Blueprints/templates to scaffold serverless .NET projects quickly. The framework supports writing functions in C# (and VB/F# where applicable), integrates with the .NET CLI and Visual Studio tooling, and allows developers to treat Lambda functions like any other managed .NET application while handling the deployment, packaging and runtime glue. Its goal is to make serverless in AWS feel natural for .NET developers—abstracting away boilerplate and letting you focus on business logic rather than deployment artifacts. It also supports advanced use cases such as .NET Core integration, source-generator annotations, and custom middleware within a function context.
    Downloads: 5 This Week
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  • 7
    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: 5 This Week
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  • 8
    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: 5 This Week
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  • 9
    Discord Rich Presence

    Discord Rich Presence

    C# custom implementation for Discord Rich Presence

    This is a C# implementation of the Discord RPC library which was originally written in C++. This avoids having to use the official C++ and instead provides a managed way of using the Rich Presence within the .NET environment. While the official C++ library has been deprecated, this library has continued support and development for all your Rich Presence needs, without requiring the Game SDK.
    Downloads: 5 This Week
    Last Update:
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  • Get full visibility and control over your tasks and projects with Wrike. Icon
    Get full visibility and control over your tasks and projects with Wrike.

    A cloud-based collaboration, work management, and project management software

    Wrike offers world-class features that empower cross-functional, distributed, or growing teams take their projects from the initial request stage all the way to tracking work progress and reporting results.
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  • 10
    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: 5 This Week
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  • 11
    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: 5 This Week
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  • 12
    SFML.Net

    SFML.Net

    Official binding of SFML for .Net languages

    SFML.Net is the official .NET binding for the Simple and Fast Multimedia Library (SFML), providing C# developers with access to a powerful multimedia and game development framework. It wraps SFML’s C++ API into a user-friendly .NET interface, making it easy to build 2D games, multimedia apps, and simulations with graphics, sound, windowing, and input support. SFML.Net keeps the design idiomatic to C#, maintaining SFML's performance and portability while providing seamless integration with .NET languages like C# and F#.
    Downloads: 5 This Week
    Last Update:
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  • 13
    MvvmCross Plugins DateTimeConverter

    MvvmCross Plugins DateTimeConverter

    A set of date and time converters

    A MvvmCross plugin that provides date and time conversion utilities for cross-platform applications, simplifying time zone and formatting tasks.
    Downloads: 4 This Week
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  • 14
    OpenAI .NET

    OpenAI .NET

    The official .NET library for the OpenAI API

    OpenAI .NET is the official client library for calling the OpenAI REST API from C# and other .NET languages, with first-class support for modern .NET patterns. It provides strongly typed clients across API areas (chat, audio, images, embeddings, moderations, batches, files, models, vector stores, responses, realtime, assistants) and works with .NET Standard 2.0 while the examples use .NET 8. You install it via NuGet and authenticate with an API key, ideally through environment variables or configuration rather than hardcoding. Every synchronous method has an async counterpart, and the library offers convenient streaming primitives for chat completions so you can process tokens as they arrive. It supports tool/function calling, structured outputs via JSON schema, audio input/output, image generation, embeddings, Whisper transcription, and assistants with retrieval augmented generation.
    Downloads: 4 This Week
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  • 15
    Veldrid

    Veldrid

    A low-level, portable graphics library for .NET

    Veldrid is a low-level, portable graphics library for .NET, providing a unified API over multiple graphics backends such as Direct3D, Vulkan, OpenGL, and Metal. It enables developers to write high-performance, cross-platform graphics applications without being tied to a specific graphics API. Veldrid is suitable for game development, simulations, and other applications requiring advanced graphics capabilities.
    Downloads: 4 This Week
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  • 16
    C# SDL
    SDL.NET is a set of object-oriented .NET bindings for the SDL gaming library and provides high-level access to audio, keyboard, mouse, joystick, TTF fonts, various image formats, sound mixing, MPEG-1, and 2D video framebuffer.
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    Downloads: 34 This Week
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  • 17
    Basic Computer Games

    Basic Computer Games

    An updated version of the classic "Basic Computer Games" book

    Basic Computer Games is a modern revitalization of the classic “Basic Computer Games” book’s collection of games, ported and expanded into various modern, memory-safe and scripting languages. It includes illustrative code examples of many classic games (e.g. Blackjack, Bowling) in multiple languages, with the goal of making the historical games accessible and educational in safe modern environments. Definitely use the most recent versions and features of the target language, but also try to keep the code samples simple and explainable – the goal is to teach programming in the target language, not necessarily demonstrate the cleverest one-line tricks, or big system "enterprise" coding techniques designed for thousands of lines of code.
    Downloads: 3 This Week
    Last Update:
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  • 18
    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: 3 This Week
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  • 19
    FakeItEasy

    FakeItEasy

    The easy mocking library for .NET

    A .Net dynamic fake framework for creating all types of fake objects, mocks, stubs etc. Easier semantics, all fake objects are just that, fakes. Usage determines whether they're mocks or stubs. Context-aware fluent interface guides the developer. Easy to use and compatible with both C# and VB.Net. Every faked instance looks and feels like an instance of the faked type. Helpful exception messages identify where a test went wrong. Raising events from faked objects. Explicit assertions, stated at the end of the test. Type-safe faking of classes that require constructor arguments. Automatic generation of dummy constructor arguments, if desired. Extensible facilities for fake and dummy creation and argument formatting. Use your fake as you would an instance of the faked type. Asserting uses the same syntax as configuring calls.
    Downloads: 3 This Week
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  • 20
    Polly

    Polly

    A .NET resilience and transient-fault-handling library for policies

    Polly is a .NET resilience and transient-fault-handling library that allows developers to express policies such as Retry, Circuit Breaker, Timeout, Bulkhead Isolation, and Fallback in a fluent and thread-safe manner. From version 6.0.1, Polly targets .NET Standard 1.1 and 2.0+. Today's cloud application, mobile, data-streaming, and IoT technologies all depend vitally on reliable connectivity. But underlying systems can fail, and networks are notoriously fickle, outages, latency, transient blips, spikes in load, all challenge 100% reliability. Polly helps you navigate the unreliable network. By providing resilience strategies in fluent-to-express policies such as Retry, WaitAndRetry, and CircuitBreaker, Polly can help you reduce fragility, and keep your systems and customers connected. Example usages are fault-tolerance for any distributed systems and inter-process calls, such as WCF, RESTful calls between microservices, calls to cloud services, Internet of Things connectivity, etc.
    Downloads: 3 This Week
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  • 21
    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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  • 22
    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: 3 This Week
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  • 23
    FastReport Open Source

    FastReport Open Source

    Free Open Source Reporting tool for .NET

    Free Open Source Reporting tool for .NET Core/.NET Framework that helps your application generate document-like reports.
    Downloads: 40 This Week
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  • 24
    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: 13 This Week
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  • 25
    Chloe

    Chloe

    A lightweight and high-performance Object/Relational Mapping(ORM)

    Chloe is a lightweight Object/Relational Mapping(ORM) library. The query interface is similar to LINQ. You can query data like LINQ and do any things(Join Query | Group Query | Aggregate Query | Insert | Batch Update | Batch Delete) by lambda with Chloe.ORM. Pay attention to splicing lambda expression trees by yourself, do not wrap your variables with ConstantExpression, otherwise, non-parameterized sql will be generated, and there is a risk of sql injection! If the entity does not explicitly specify any auto-increment columns and the primary key is of type Int16, Int32, or Int64, the default primary key is the auto-increment column. If it is not an auto-increment column, it needs to be marked with the attribute NonAutoIncrementAttribute.
    Downloads: 2 This Week
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