This guide explains how to use the Source2Toolkit SDK to build your own plugins.

The SDK provides everything needed to compile plugins against Source2Toolkit, including:

KHook headers (bundled as a submodule)
Build configuration and CMake helpers
HL2SDK (CS2) and Protobuf — resolved via environment variables

Getting the SDK

Clone the SDK repository:

git clone https://github.com/SlynxCZ/source2toolkit-sdk.git
cd source2toolkit-sdk

The SDK only includes KHook as a submodule (for headers). HL2SDK (CS2) and Protobuf must be available on your system and resolved through environment variables — see below.

Dependencies

The SDK uses resolve_dep to locate external dependencies at configure time:

resolve_dep(KHOOK    KHOOK      ${CMAKE_CURRENT_SOURCE_DIR}/vendor/khook)
resolve_dep(SOURCESDK HL2SDKCS2)
resolve_dep(PROTOBUFS CSGO_PROTO)

KHOOK is bundled inside the SDK. The other two must be provided via environment variables:

Variable	Description
`HL2SDKCS2`	Path to your HL2SDK CS2 checkout
`CSGO_PROTO`	Path to your CS:GO Protobuf headers

Set these before running CMake:

# Linux / macOS
export HL2SDKCS2=/path/to/hl2sdk-cs2
export CSGO_PROTO=/path/to/csgo-proto

# Windows (PowerShell)
$env:HL2SDKCS2 = "C:\path\to\hl2sdk-cs2"
$env:CSGO_PROTO = "C:\path\to\csgo-proto"

Project Setup

A typical plugin project using the SDK looks like this:

my-plugin/
├── CMakeLists.txt
├── src/
│   └── plugin.cpp
└── vendor/
    └── source2toolkit-sdk/

CMake Configuration

To use the SDK, include it as a subdirectory and use the provided helper function.

cmake_minimum_required(VERSION 3.18)
project(my-plugin CXX)

set(CMAKE_CXX_STANDARD 20)

add_subdirectory(vendor/source2toolkit-sdk)

add_s2toolkit_plugin(my_plugin
    src/plugin.cpp
)

The add_s2toolkit_plugin function automatically configures linking, include paths, and output format.

Example Plugin

Below is a minimal working plugin using the SDK:

#include "source2toolkit/IToolkitPlugin.h"
#include "source2toolkit/utils/log.h"

class Plugin final : public IToolkitPlugin
{
public:
    bool Load(PluginId id, IToolkitAPI* api, char* error, size_t maxlen, bool late) override
    {
        TOOLKIT_SAVEVARS();
        api->AddListener(this, this);
        TOOLKIT_LOG(this, "Hello World! Plugin loaded.\n");
        return true;
    }

    bool Unload(char*, size_t) override
    {
        TOOLKIT_LOG(this, "Plugin unloaded.\n");
        return true;
    }

private:
    const char* GetName() override { return "My Plugin"; }
    const char* GetVersion() override { return "1.0.0"; }
    const char* GetAuthor() override { return "You"; }
    const char* GetDescription() override { return "My first plugin"; }
};

Plugin g_Plugin;
TOOLKIT_EXPOSE(my_plugin, g_Plugin);

Building the Plugin

mkdir build && cd build
cmake ..
cmake --build . --config Release

After building, you will get:

my_plugin.stx

Output

The compiled plugin uses the .stx extension and is ready to be placed into:

/game/csgo/addons/source2toolkit/plugins/

What the SDK Handles

The SDK automatically configures:

Platform-specific compiler flags
Linking against HL2SDK and engine libraries
Protobuf integration
ABI compatibility (Linux / Windows)
Include directories for Source 2 and KHook headers
Plugin output format (.stx)

Platform Notes

Linux

Uses static linking for standard libraries
Enforces _GLIBCXX_USE_CXX11_ABI=0

Windows

Requires MSVC compiler
MinGW is not supported

Summary

Using the SDK is simple:

add_subdirectory(source2toolkit-sdk)

add_s2toolkit_plugin(my_plugin
    src/plugin.cpp
)

Make sure HL2SDKCS2 and CSGO_PROTO are set in your environment, then build — that's it.

You are now ready to start developing plugins with full access to Source 2 internals.

SDK & Building