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Msquic

Cross-platform, C implementation of the IETF QUIC protocol, exposed to C, C++, C# and Rust.

From microsoft·Updated June 16, 2026·View on GitHub·

MsQuic is a Microsoft implementation of the [IETF QUIC](https://datatracker.ietf.org/wg/quic/about/) protocol. It is cross-platform, written in C and designed to be a general purpose QUIC library. MsQuic also has C++ API wrapper classes and exposes interop layers for both [Rust](https://docs.rs/msquic/latest/msquic/) and C#. The project is written primarily in C, distributed under the MIT License license, first published in 2019. It has gained significant community traction with 4,713 stars and 674 forks on GitHub. Key topics include: c, cpp, cross-platform, csharp, network-programming.

Latest release: v2.5.9-rc
June 3, 2026View Changelog →
<h1 align="center"><img src="docs/images/readme_logo.png" width="500" alt="MsQuic logo"/></h1>

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MsQuic is a Microsoft implementation of the IETF QUIC
protocol. It is cross-platform, written in C and designed to be a general purpose QUIC library. MsQuic also has C++ API wrapper classes and exposes interop layers for both Rust and C#.

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Protocol Features














QUIC has many benefits when compared to existing "TLS over TCP" scenarios:

  • All packets are encrypted and handshake is authenticated with TLS 1.3.
  • Parallel streams of (reliable and unreliable) application data.
  • Exchange application data in the first round trip (0-RTT).
  • Improved congestion control and loss recovery.
  • Survives a change in the clients IP address or port.
  • Stateless load balancing.
  • Easily extendable for new features and extensions.

Library Features

MsQuic has several features that differentiates it from other QUIC implementations:

  • Optimized for client and server.
  • Optimized for maximal throughput and minimal latency.
  • Asynchronous IO.
  • Receive side scaling (RSS) support.
  • UDP send and receive coalescing support.
  • Kernel stack bypass via XDP.

Documentation

Contributing

For information on contributing, please see our contribution guidelines. Feel free to take a look at our Good First Issues list if you're looking for somewhere to start. If you'd just like to talk, come chat with us on Discord.

Contributors

Showing top 12 contributors by commit count.

View all contributors on GitHub →

This article is auto-generated from microsoft/msquic via the GitHub API.Last fetched: 6/17/2026