There are 2 repositories under source-sdk topic.
Bullet Physics Injection for Source SDK 2013
Original HL2 Source SDK from 2004
A Source Engine 2013 SP mod aimed to provide bug fixes and various development features
Team Fortress: Invasion brought over to Source 2013.
Cheat for Garry's Mod (x64)
Portal 2 assets converted to use in Source SDK 2013
BrainBread 2 Source Code
My mod that adds some new features
Half-Life 2 Deathmatch Bug fixes (HL2DM Bug fixes)
A small library that aims to help with converting Valve's KeyValue (VDF) format to JSON and vice versa
Mobile Forces Source
Grey Source 2021
Standalone ValveProjectCreator with some bugs fixing.
The SDK for Grey Source 2019, made to build on Microsoft Visual Studio 2019
A project for all my game-projects based on Mapbase
A simple Blazor powered game server browser
Untouched Alien Swarm SDK for modern systems
A tiny launcher for Team Fortress 2 Classic on Windows, written in Rust.
Single header Source SDK for CS:S
[WIP] Mc-Source is a tool capable of converting Minecraft structures to Source-compatible maps.
FGDs for u5-maps with some changes from the main repository