Build LLM-powered agents in C++.

---

Forgeant is a C++23 agent framework that gives you tool use, structured output, and a ReAct agent loop across multiple LLM providers -- without leaving C++.

Full API reference at forgeant.dev.

#include <forgeant/forgeant.hpp>

auto agent = forgeant::Agent::create("anthropic", {
    .api_key = "sk-...",
    .model = "claude-sonnet-4-20250514",
});

auto result = agent->run("What is the capital of France?");
std::cout << result.output << std::endl;

Why Forgeant?

• Native C++ agents. No Python subprocess, no FFI bridge, no runtime overhead. Your agent runs where your application runs.
• Type-safe tools. Define tools as C++ structs. JSON Schema is generated from your types. The agent calls them automatically.
• Structured output. Get typed C++ structs back from LLMs. Not strings. Not JSON you have to parse yourself.
• Multi-provider. Anthropic, OpenAI, and Ollama from the same API. Switch with one parameter.
• Tested seriously. ASan, UBSan, Valgrind, clang-tidy, 139 tests across GCC, Clang, and macOS on every commit.

Get Started

include(FetchContent)
FetchContent_Declare(forgeant
    GIT_REPOSITORY https://github.com/Jimdrews/forgeant.git
    GIT_TAG main)
FetchContent_MakeAvailable(forgeant)
target_link_libraries(your_target PRIVATE forgeant::forgeant)

# Or build from source
git clone https://github.com/Jimdrews/forgeant.git && cd forgeant
cmake --preset dev && cmake --build --preset dev && ctest --preset dev

What You Can Build

Give your agent tools:

agent->add_tool(forgeant::make_tool<WeatherParams>(
    "get_weather", "Get current weather",
    [](WeatherParams p) { return "72F and sunny in " + p.city; }
));

auto result = agent->run("What's the weather in Denver?");

Get structured data back:

auto result = agent->run<MovieReview>("Review 'The Matrix' (1999).");
std::cout << result.output.title << ": " << result.output.rating << "/10" << std::endl;

Run multi-step reasoning:

auto agent = forgeant::Agent::create("anthropic", {
    .api_key = "sk-...",
    .model = "claude-sonnet-4-20250514",
    .max_iterations = 10,
});

agent->add_tool(search_tool);
agent->add_tool(calculator_tool);

auto result = agent->run("Find the average price of items matching 'widget'.");
// Agent reasons, calls tools, and responds — automatically

Supported Compilers

GCC 14+ • Clang 19+ • AppleClang (latest) • C++23 required

Contributing

Contributions are welcome. See CONTRIBUTING.md for guidelines.

License

MIT