netcode.io vs reliable

netcode.io is a free, open-source client/server protocol for real-time multiplayer games. It uses UDP to exchange unreliable, unordered packets without TCP head-of-line blocking. Game backends can issue connect tokens that authorize clients, while servers assign connecting clients to configured slots and reject connections when slots are full. The protocol supports clean disconnects and timeouts for hard disconnects. Packets are encrypted and signed with libsodium, with protections described against crafted packets, replay attacks, and amplification attacks. IPv4 and IPv6 are supported, along with packet tagging intended to reduce Wi-Fi jitter. Implementations are listed for C, C#, Go, Rust, Unity, Unreal Engine 4, and TypeScript. Builds use CMake on Windows, macOS, and Linux, with CMake 3.16 or later and a vendored libsodium subset by default. The BSD 3-Clause project documents REST-based token requests and reports a nonce-reuse issue affecting versions 1.3.5 and earlier, fixed in 1.4.0.

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