FreeCodingCourses
Intermediate
Python

Build it free

Build a REST API for Free

A working REST API with routes, a database, and JSON responses you can call from any client.
About 120 hours2 stages, 2 free courses

The short version

A REST API is the backend that mobile apps and web front ends talk to. You can build a real one for free in about 120 hours, first learning Python well, then learning web programming with Flask and a database. By the end you have an API with real routes that reads and writes data and returns JSON, the exact shape of code backend teams ship every day.

What you will build

  • 01A set of REST endpoints (GET, POST, PUT, DELETE) that follow HTTP conventions
  • 02A database layer so your data survives a restart
  • 03JSON responses and proper status codes any front end can consume
  • 04Request validation and error handling instead of crashing on bad input

The path, stage by stage

Work through these free courses in order. Each stage links to the full course details, its platform, and what you walk away able to do.

StageCoursePlatformHoursWhat you gain
1. Learn Python properlyCS50's Introduction to Programming with PythonHarvard CS5036CS50P teaches you Python the way a backend job needs it: functions, error handling, tests, and reading other people's code. You finish able to write and debug real Python, not just tutorials.
2. Build web apps and APIs with PythonCS50's Web Programming with Python and JavaScriptHarvard CS5084CS50's Web Programming course teaches Flask, routes, request handling, and connecting to a database. This is the core of any REST API: you learn to take an HTTP request in and send JSON back out.

Why these courses, not the alternatives

We send you to CS50P before any framework because the most common reason a beginner API breaks is shaky Python, not shaky Flask. CS50P from Harvard is the strongest free Python course for exactly the skills an API needs: functions, tests, and error handling. Then CS50's Web Programming course is our pick over a random Flask video because it teaches routing and databases as one connected thing, with real assignments graded against real requirements. We use a framework (Flask) on purpose per our tutorial code standard: a real job pulls in Flask or FastAPI, so hand-rolling a server would teach a pattern nobody ships.

Before you start

Comfort using a terminal and installing software. You do not need prior Python; the first stage covers it.

What you walk away with

A working REST API with routes, a database, and JSON responses you can call from any client.

Start with the first course

CS50's Introduction to Programming with PythonCS50's Web Programming with Python and JavaScript

Apply it with a code-along tutorial

Frequently asked questions

Which framework should I use to build a REST API in Python?

Flask and FastAPI are the two mainstream choices. CS50's Web Programming course teaches Flask, which is the gentler starting point. FastAPI is worth learning next for typed, async APIs.

Do I need to know SQL to build an API?

For anything that stores data, yes, at a basic level. The web programming stage introduces enough SQL to get started. Our SQL courses go deeper when you are ready.

Can I build an API without a database?

You can start with in-memory data to learn routing, but any real API needs persistence. That is why a database is part of this path rather than an afterthought.

Is Python a good language for a first API?

Yes. Python with Flask has one of the shortest paths from zero to a working endpoint, which is why it is the language we picked for this build.

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Where this build leads