Open-source alternatives to NetStack

Agones is a Kubernetes game server orchestrator designed for deploying, scaling, and managing dedicated multiplayer game server processes across a distributed cluster. It provides the core infrastructure needed to provision individual or grouped server processes to support real-time multiplayer gaming sessions. The system includes a fleet manager to automate the lifecycle of server groups based on player demand and a health monitor to track the connectivity and operational status of active processes. It integrates with cluster autoscalers to synchronize server resource requirements with cloud

Nakama is a distributed server framework designed for real-time multiplayer games and social applications. It provides an authoritative runtime environment for executing game logic, ensuring consistent state and cheat-resistant gameplay across diverse client platforms. The system acts as a centralized backend, managing persistent player identities, social graphs, and real-time communication channels to support complex multiplayer interactions. The platform distinguishes itself through an integrated suite of LiveOps tools that allow developers to manage game economies, schedule time-bound even

A simple to use TCP and UDP networking library for .NET. Compatible with Unity.

Packet acknowledgement system for UDP

yojimbo is a network library for client/server games written in C++.

Lite reliable UDP library for Mono and .NET

Highly scalable realtime pub/sub and RPC framework

Colyseus is a real-time multiplayer game framework for Node.js that provides an authoritative server model, delta-compressed state synchronization, and room-based session orchestration. It is designed to handle the core infrastructure of multiplayer games, including matchmaking, state management, and scalable process distribution across multiple servers. The framework distinguishes itself through its schema-based state definition, which enables automatic serialization and change tracking, combined with a binary WebSocket protocol for low-latency updates. Its matchmaking pipeline routes player

MagicOnion is a .NET RPC framework used to build type-safe remote procedure call services using shared interfaces for communication between servers and clients. It functions as a binary serialization framework and a distributed service orchestrator, providing a network layer for low-latency streaming and real-time data exchange. The project distinguishes itself through an AOT-compatible network client that uses source generators to support ahead-of-time compilation in restricted runtime environments. It enables bidirectional communication and real-time data streaming, allowing servers and mul

RakNet is a cross platform, open source, C++ networking engine for game programmers.

Master Server framework for Unity

See various forks, also please join the Forge Community fork of Forge Alloy! -> https://github.com/ForgeAlloyCommunity/ForgeAlloy

The socket manager

Lidgren Network Library

Good Game, Peace Out Rollback Network SDK

KCP is a low-latency transport protocol and reliability layer designed to provide TCP-like guaranteed delivery and ordering over UDP. It implements an automatic repeat request protocol to minimize network jitter and delays, prioritizing timeliness over bandwidth efficiency. The project distinguishes itself through a pluggable congestion controller and flow control logic, allowing the transport layer to be tuned for specific network environments. It includes a NAT keep-alive system that uses periodic heartbeat packets to maintain active communication paths and prevent address translation timeo

GameNetworkingSockets is a UDP networking library providing secure transport, peer discovery, and traffic control systems. It implements a networking layer for reliable and unreliable messaging over UDP, including tools for message fragmentation and reassembly. The project features a peer-to-peer NAT traversal tool for establishing direct host-to-host connections by punching through firewalls and network address translation layers. It secures network traffic through encrypted transport and secure key exchange. The library includes a traffic manager to organize data into prioritized lanes to