Fastmcp

FastMCP is a Python framework for building applications on the Model Context Protocol, the standard that lets language models call external tools and read external data. It covers three roles through one API: servers that expose Python functions, data and instructions as MCP tools, resources and prompts; clients that connect to local or remote MCP servers; and apps that return interactive interfaces such as forms, tables and charts alongside ordinary tool results. It is aimed at developers who want the protocol handled for them rather than reimplemented in every project. Declaring a plain Python function is enough for the framework to derive its schema, validate inputs and outputs, and expose it over MCP. On the client side it handles protocol negotiation, authentication and connection lifecycle, so application code stays ordinary Python. The framework also manages transport selection and protocol compatibility, which matters when one server has to serve callers running different protocol versions. Clients can be driven from Python, from the command line, or from another MCP application. The framework is open source and free to install from the Python package index, and the documentation site publishes no price list or paid tier for it. Commercial hosting and governance for MCP servers are sold separately by the same team under a different product name, with its own pricing page. Two facts are worth knowing before choosing it. The project created the high level Python API that was incorporated into the official MCP Python SDK in 2024 and has continued as a standalone framework since, and the current major release was rebuilt around the newer version of the MCP protocol, so older code may need revision.