FastAPI for AI Engineers — Part 1: Why Every AI Backend Is Moving Toward FastAPI

You open ChatGPT. You type a prompt. Within seconds: your request reaches a backend server, the backend communicates with an LLM, retrieves memory, queries vector databases, processes context, and streams responses back to you in real time. Modern AI applications are no longer just “apps.” They are systems made up of multiple services constantly communicating with each other through APIs. And one framework has quietly become the default choice for building these modern AI backends: Fast