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PYTHON · FASTAPI · LEARN BY BUILDING

Build your first API.
Understand every request.

Start with a JSON response and finish with a tested, database-backed task API. Learn how Python types, validation, dependencies and HTTP work together.

Start learning →Explore the lessons
8 guided lessons8 source downloads1 practical task API

What you need

Basic Python variables, dictionaries, functions and classes. Use Python 3.12 or 3.13, a code editor and a browser. The first lesson covers virtual environments on macOS, Windows and Linux.

No Java, Maven, frontend framework or database server is required.

How to learn

Read the explanation, run the complete example, check the response and attempt the exercise. Each download is a standalone checkpoint with source files, dependencies and an offline lesson.

The early lessons teach individual concepts. From lesson 4, evolve one task API from memory to SQLite, then add protection and tests.

YOUR LEARNING PATH

From Python setup to deployment

  1. 01

    Python setup and your first API

    Create an isolated Python environment and return JSON from a running server.

  2. 02

    Paths, queries and Python types

    Read URL inputs and reject invalid values before your function runs.

  3. 03

    Request bodies and response models

    Validate JSON with Pydantic and define a predictable response.

  4. 04

    Build an in-memory task API

    Create, list, read, replace and delete tasks using HTTP methods.

  5. 05

    Persist tasks with SQLite and dependencies

    Keep tasks after restarts and manage a database connection per request.

  6. 06

    Protect the API with a dependency

    Require a secret header for every task operation.

  7. 07

    Test success, errors and access control

    Run repeatable checks without touching your development database.

  8. 08

    Run and deploy the finished API

    Package the application and understand the operational requirements of a public API.

A clear, practical scope

Build a shared-key service API with SQLite. Learn the limits of in-memory storage and shared credentials before moving to multi-user authentication or a managed database.

Keep exploring

Examples use Pydantic 2. Dependency ranges are included in each download; freeze the versions you test before deploying.

Official FastAPI documentation ↗

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