Flask Tutorial

Home Next

Flask is a lightweight Python web framework built on a very different philosophy from Django: instead of shipping every piece for you, Flask gives you a small, solid core — routing, request handling, and Jinja2 templating — and lets you add exactly the pieces your project actually needs, as extensions, one at a time. This track covers 37 lessons, from your first route through templates, forms, a real database layer with SQLAlchemy, user authentication, blueprints for structuring larger apps, building a REST API, testing, and deployment. Throughout the whole track we build one running example together — Bookshelf, a personal reading tracker where users log books, organize them onto shelves, and tag them — so every concept lands in a real, connected context rather than isolated snippets.

Where this fits: This track assumes you've been through Core Python (variables, functions, classes, OOP) — if any of that feels shaky, the Core Python track is a good foundation first.

What Makes Flask Different

Compared to...	Flask's approach
Django	Flask is a "microframework" — routing and templating ship built in, but the database layer, forms, and login system are all separate packages you choose and wire in yourself
A framework with a mandatory project layout	Flask doesn't force a folder structure on you — a whole working app can be a single file, and you grow the structure as the project grows
An all-in-one ORM/admin/auth bundle	Flask's ecosystem is a collection of small, focused extensions (Flask-SQLAlchemy, Flask-Login, Flask-WTF) that you compose together instead of inheriting one fixed stack

A Quick Look Ahead

Example: A Route Rendering a Template

# app.py
from flask import Flask, render_template

app = Flask(__name__)

@app.route('/books')
def book_list():
    books = Book.query.filter_by(status='reading').all()
    return render_template('books/list.html', books=books)

Note: This is correct, real Flask code — but this website's own project doesn't run a Flask server, so you won't see it actually execute on this page. Follow along by creating your own project after the next few setup pages.

What You'll Learn In This Track

Area	Covered in
Foundations	Installation, your first app, project structure, the app factory pattern, configuration
Routing & requests	Routes, dynamic URLs, the request/response objects, error handling
Templates	Jinja2, template inheritance, custom filters, static files
Forms & state	Flask-WTF, validation & CSRF, file uploads, sessions, flash messages
The data layer	Flask-SQLAlchemy, models & relationships, migrations, CRUD, querying & pagination
Architecture	Blueprints, the application context, and Flask's globals
Users & security	Flask-Login, registration & password hashing, authorization, email, security best practices
Building APIs & shipping it	REST APIs, Marshmallow & JWT, testing, caching, background tasks, deployment

Next steps: Head to Why Flask? before we install anything — understanding the philosophy makes everything after it click faster.

Home Next