Game Network Protocols & APIs (Game Decompilations & Reimplementations): open-source projects that exist because someone reverse engineered a closed product, sorted by GitHub stars.
High-level JavaScript API for creating Minecraft bots
Proxy translating Minecraft Bedrock clients to Java Edition servers
Deck tracker for Hearthstone on Windows that reads game logs and memory
Open-source client for Xbox Cloud Gaming (xCloud) and Xbox home streaming
High-performance Minecraft Java proxy server
Lightweight console Minecraft client for chat and automated scripts
XMPP proxy that lets you appear offline in League of Legends, VALORANT and LoR
Lets newer Minecraft clients connect to older server versions by translating packets
Open-source custom client and automation tool for Ragnarok Online
Parse and serialize Minecraft Java packets, with auth and encryption
Pokemon Go API
Interface directly with Steam CM servers from Node.js (archived)
Collection of Go libraries for the Minecraft Java protocol and data formats
Automated tracking of Counter-Strike 2 game file, string and protobuf changes
Language-independent Minecraft protocol and game data for clients, servers and libraries
Java library for Minecraft Java client/server protocol communication
Browser and companion tool for Kantai Collection that reads game API traffic
Minecraft Java client networking library in Python
Unofficial Pokemon GO API in Python (archived)
Python package to communicate with Switch, Wii U and 3DS servers
Python Steam trading library using Steam's internal web endpoints
Standalone proxy translating between Minecraft protocol versions, including Bedrock and classic
Reverse engineered REST API of the Nintendo Switch iOS app
Nintendo Switch Online/Parental Controls app APIs. Show your Nintendo Switch presence in Discord, get friend...
Node.js Steam trade offer management library
Documentation for internal VALORANT client API endpoints
Auto-tracked protobuf definitions extracted from Steam, CS2, Dota 2, Deadlock and TF2
Go library for Minecraft Bedrock Edition networking, clients and proxies
Node.js module to interact with Steam Community web interfaces
Unofficial VALORANT API built on the in-game API endpoints
Unofficial documentation of Fortnite and Epic Games API endpoints
Minecraft Bedrock protocol library with authentication and encryption
Successor to splatnet2statink. Takes battle data from the SplatNet 3 app and uploads it to stat.ink!
Steam's network protocol implemented in Go for automation without a Steam client
JavaScript library to get trophy, user and game data from the PlayStation Network
Research and documentation of Epic Games' undocumented APIs
Java protocol library for Minecraft Bedrock Edition
Web-based 3D viewer for Minecraft servers and bots
Shows Nintendo Switch playing status in Discord using the Nintendo Switch Online app API
PHP wrapper for the PlayStation Network API
Node.js client for the CS2 game coordinator protocol
PlayStation Network API written in Node.js
Kantai Collection helper tool that parses game API traffic
Fetches Splatoon 2 battle data from the SplatNet 2 app API and uploads to stat.ink
Unofficial Node.js library for the Rust+ companion protocol
Automated dumps of Valve game files and protos to track changes
Patches Wii channels to use RiiConnect24's revived WiiConnect24 services
Community API for Helldivers 2 game data
Hearthstone Python library: card defs, DBF, enums and log parser
Node.js generator for Steam Guard mobile TOTP codes and confirmation keys
Async Python wrapper for the Steam API and Steam CM protocol
Wii U Aroma plugin that patches the console to use Pretendo Network servers
Browser extension with notifications and small-window play for Kantai Collection
Unofficial Rust+ desktop app
A python library to authenticate with Xbox Live via your Microsoft Account and provides Xbox related Web-API.
Node.js module implementing Steam's auth server login to obtain refresh and web tokens
[Mirror] PlayStation Network API Python
Go client for the Dota 2 game coordinator protocol
PHP implementation of the Minecraft Bedrock network protocol
JavaScript parser for Super Smash Bros. Melee Slippi replay files
Website and scraper collecting GOG game data from GOG's internal APIs
Documentation of League of Legends LCU and Riot Client local API endpoints
PlayStation Network API client in Python
Unofficial desktop client for Nintendo SplatNet 2
Pipes Steam PICS changelist events to websockets using SteamKit
Python module to interact with the CS:GO game coordinator
Kantai Collection browser for iPhone, iPad and Android
Python interface for the League of Legends client local API
Open-source SA:MP mobile multiplayer client
Xbox Cloud Gaming client for PlayStation Vita
Unofficial native GeForce NOW and Xbox Cloud Gaming client for the New Nintendo 3DS
Node.js connector for the League of Legends client (LCU) local API
Third-party client app for Star Citizen
TERA DPS meter based on decoded game packets
Xbox Live authentication library for Node.js
Unofficial Node.js library for the VALORANT client API
Captures and decodes Umamusume Pretty Derby (DMM) packets on Windows
Python implementation of the Xbox One NANO game-streaming protocol
Go implementation of Nintendo's PRUDP/NEX game server protocol for Pretendo
Patch for old PC games replacing defunct GameSpy services with OpenSpy
Unofficial documentation of Axie Infinity's GraphQL endpoint
Agar.io protocol reverse engineering
PictoChat protocol adapter implementing the Nintendo DS PictoChat wireless protocol
Python client for the unofficial Screeps API
Unofficial Aternos API in Python
Makes almost all of the data exposed by Mario Maker 2 servers public through an API
Node.js library for RuneScape and Old School unofficial API endpoints
Kantai Collection external log and analysis tool
Tentacli is a framework for building extensible network protocol clients via modular plugins
Node.js agar.io client implementation
.NET Hearthstone card database extracted from game data
Home Assistant integration for the PlayStation Network via its unofficial API
Microsoft/Xbox Live authentication flow for Minecraft clients
Python implementation of the Xbox One SmartGlass core protocol
Automated Final Fantasy XIV network opcode discovery
Reverse engineering Blue Archive
Unofficial API proxy for Project Sekai game data
Unofficial Fortnite client in JavaScript built on the Epic Games launcher protocol
API to build Haxball clients and bots via its reversed protocol
Reverse engineered Rocket League internal HTTP and WebSocket API
Python library implementing the PlayStation Remote Play protocol
FastAPI proxy exposing Helldivers 2 API data for community developers
Reverse engineered packet documentation for Final Fantasy XI
Unofficial FIFA Ultimate Team API client
Python client library for Club Penguin private servers
Cleaned-up GameSpy SDK used to build GameSpy replacement servers
Multiplatform unofficial client for the Fox Go server
World of Tanks unofficial API description
Simple Xbox Live API wrapper for Node.js
Trackmania 2020 unofficial API documentation
Resources and code for Valorant's unofficial API
Reverse-engineered client/server protocol of the browser game Agar.io
Documentation website for Blizzard's Battle.net classic protocols
.NET libraries for the Phantasy Star Online: Blue Burst protocol
Protocol bridge that lets Minecraft 1.21 clients join Hytale servers (PC)
Go implementations of common Nintendo NEX methods shared by Pretendo game servers
PlayStation trophy tracking site with leaderboards built on the PSN API
Unofficial documentation of the Steam client
Unofficial Python client for the EA Sports FC 27 Pro Clubs API
Protocol documentation of GameSpy services for replacement servers
Wrapper for the unofficial Steam Market pricing API
Python library to control a PS4 via the PS4 Second Screen protocol
Plugin and injection framework for the Star Wars Galaxies client
Desktop app to track Halo Infinite stats and progression via the unofficial Halo API
Unofficial API for the krunker.io game social page
Unofficial Node.js library for Mojang's HTTP APIs (auth, profiles, skins)
Documentation of Hytale's QUIC/UDP network protocol, extracted from the game
Server that mimics the Minecraft 1.8.9 network protocol
Reverse-engineered network protocol of the browser game splix.io
Battle.net v1.0 password hash algorithm in several languages
C# library to read and verify PSN authentication tickets for custom servers
Passive protocol decoder and analysis toolkit for AION 2
Passive network sniffer and protobuf decoder for the Dofus 3 game protocol
CheckRevision implementation for Classic Battle.net game version checks
Unofficial Growtopia API for item data and sprites
Extracts NEX server access keys from Wii U and 3DS game dumps
Unofficial read-only API client for Xbox LIVE
Crypto library for the PlanetSide 1 client protocol
Unofficial Final Fantasy XIV toolkit for Ruby with a Lodestone scraper
PlanetSide 1 event logger GUI for protocol analysis
Wireshark dissector for Sony's Medius online protocol
Connects to and logs VALORANT XMPP presence and roster events
Technical specification of the Battlefield Heroes master server protocol
Parses NEX DDL protocol definitions out of Wii U and 3DS game dumps
JSON captures of Endless Online protocol packets for server emulator work
Unofficial Halo Infinite REST API client for Rust: service record and match history
Builds docs for NEX protocols from DDL parse trees in Wii U and 3DS game dumps
Packet parser for WildStar, from the NexusForever emulator project
Unofficial API wrapper and documentation for the Halo Infinite web services