MsQuic is a free and open source implementation of the IETF QUIC protocol written in C[1] that is officially supported on the Microsoft Windows (including Server), Linux, and Xbox platforms.

[2] It is designed to be a cross-platform general purpose QUIC library optimized for client and server applications benefitting from maximal throughput and minimal latency.

[4] Among its features are, in part, support for asynchronous IO, receive-side scaling (RSS), UDP send and receive coalescing, and connection migrations that persist connections between client and server to overcome client IP or port changes,[5] such as when moving throughout mobile networks.

[6] Both the HTTP/3[7] and SMB stacks[8] of Microsoft Windows leverage MsQuic, with msquic.sys providing kernel-mode functionality.

[9] User-mode programs can implement MsQuic, with support 0-RTT, through msquic.dll, which can be built from source code or downloaded as a shared library through binary releases on the repository.