Streaming APIs with FastAPI and Next.js — Part 1

Streaming data in the browser is one of those things that feels magical the first time you see it: data appears live — no need to wait for the full response to load. In this two-part series, we’ll walk through building a small full-stack app that uses FastAPI to stream data and a Next.js frontend to consume and render it in real-time. There are many ways to stream data in the browser, from WebSockets to Server-Sent Events (SSE). But in this post, we’ll focus on a lesser-known method: chunked transfer encoding. This technique allows the server to send data in small, manageable chunks, which the browser can process as they arrive. This post focuses on the frontend bit. In Part 2, we’ll dive into building the FastAPI backend.

Mar 30, 2025 - 10:28

Streaming APIs with FastAPI and Next.js — Part 1

Streaming data in the browser is one of those things that feels magical the first time you see it: data appears live — no need to wait for the full response to load. In this two-part series, we’ll walk through building a small full-stack app that uses FastAPI to stream data and a Next.js frontend to consume and render it in real-time.

There are many ways to stream data in the browser, from WebSockets to Server-Sent Events (SSE). But in this post, we’ll focus on a lesser-known method: chunked transfer encoding. This technique allows the server to send data in small, manageable chunks, which the browser can process as they arrive.

This post focuses on the frontend bit. In Part 2, we’ll dive into building the FastAPI backend.