Modern C++23 LLM client built with modules — import and chat, OpenAI-compatible, template-ready

llmapi provides a typed Client<Provider> API for chat, streaming, embeddings, tool calls, and conversation persistence. The default config alias Config maps to OpenAI-style providers, so the common case does not need an explicit openai::OpenAI wrapper.

mcpp new myagent --template llmapi && cd myagent
export OPENAI_API_KEY="sk-..."
mcpp run

Templates ship with the library and version-track it automatically:

mcpp new --list-templates llmapi              # list available templates
mcpp new mybot --template llmapi:chat        # interactive streaming chat CLI
mcpp new mybot --template llmapi:anthropic   # Anthropic provider
mcpp new mybot --template llmapi:deepseek    # OpenAI-compatible endpoint (DeepSeek)

Or add it to an existing mcpp project:

mcpp add llmapi

[dependencies.mcpplibs]
llmapi = "0.2.8"

import mcpplibs.llmapi;
import std;

int main() {
    using namespace mcpplibs::llmapi;

    auto apiKey = std::getenv("OPENAI_API_KEY");
    if (!apiKey) {
        std::println(stderr, "OPENAI_API_KEY not set");
        return 1;
    }

    auto client = Client(Config{
        .apiKey = apiKey,
        .model = "gpt-4o-mini",
    });

    client.system("You are a concise assistant.");
    auto resp = client.chat("Explain why C++23 modules are useful in two sentences.");

    std::println("{}", resp.text());
    return 0;
}

• import mcpplibs.llmapi with C++23 modules
• Strongly typed messages, tools, and response structs
• Sync, async, and streaming chat APIs
• Embeddings via the OpenAI provider
• Conversation save/load helpers
• OpenAI-compatible endpoint support through openai::Config::baseUrl
• Project templates: mcpp new <name> --template llmapi[:<template>]

• openai::OpenAI for OpenAI chat, streaming, embeddings, and OpenAI-compatible endpoints
• anthropic::Anthropic for Anthropic chat and streaming
• Config as a convenient alias for openai::Config

Compatible endpoints can reuse the OpenAI provider:

auto client = Client(Config{
    .apiKey = std::getenv("DEEPSEEK_API_KEY"),
    .baseUrl = std::string(URL::DeepSeek),
    .model = "deepseek-chat",
});

git clone https://github.com/mcpplibs/llmapi.git && cd llmapi
mcpp build

• Getting Started
• Providers
• C++ API Guide
• Using llmapi with xmake
• Docs index

Apache-2.0 - see LICENSE