GameNetworkingSockets vs yojimbo

GameNetworkingSockets is a free BSD-3-Clause transport library for games that sends reliable and unreliable messages over UDP. It handles messages larger than the underlying MTU through fragmentation and reassembly, with retransmission for reliable messages. Packets use AES-GCM-256, while Curve25519 supports key exchange and certificate signatures. Peer-to-peer connections can use Google WebRTC ICE for NAT traversal, with an option to plug in a signaling service. Multiple message lanes can share one connection under strict priorities or weighted bandwidth rules. Included diagnostics simulate packet latency and loss and measure detailed statistics. The library is written in C++ and also exposes a plain C interface; third-party bindings are listed for C#, Go, and Rust. Build instructions cover Linux, Windows, macOS, and iOS. Steam is not required for the open-source library, but authentication, signaling, and Steam Datagram Relay remain Steam-only services. Higher-level entity serialization, delta encoding, and compression are not included.

yojimbo has no write-up on Specifiction yet; its figures are above.