ConnectOnion

ConnectOnion is an open-source Python AI agent framework for developers who want to build agents with minimal boilerplate. Its core Agent API turns regular typed Python functions into tools automatically, and the documentation shows quick setup with pip install connectonion and a two-line agent pattern. The framework supports OpenAI, Anthropic, and Gemini models, and includes documentation for CLI commands, logging, debugging, TUI components, plugins such as ReAct, Eval, Shell, approvals, skills, subagents, and built-in tool integrations such as shell, file tools, browser automation, Gmail, Outlook, Calendar, memory, and todo workflows. It is best suited for engineering teams building custom LLM agents, tool-calling assistants, multi-agent workflows, and Python-based automation without adopting a heavy framework layer.