Most JWT tutorials stop at "here's your token". But a token alone doesn't protect anything. The real security bugs happen one step later, when a logged-in customer can read someone else's bank account by changing an ID.

In this tutorial we build a small banking REST API with Flask, Flask-JWT-Extended and SQLite, and we test every success and failure path:

secure password hashing

login that returns a JWT access token

protected routes with a Bearer token

customer data isolation : you only see your own accounts

an admin-only endpoint

Postman tests plus 7 automated tests

Project page: https://github.com/rainyreaksmey/python-jwt-authentication-api

The code below is simplified to show each idea clearly. The video builds every line on screen.

The endpoints

GET /api/health : public

POST /api/auth/login : public

GET /api/me : JWT

GET /api/accounts : JWT

GET /api/transactions : JWT

GET /api/admin/users : admin JWT

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