Habit Tracker API

A backend API for tracking personal habits. Users register and log in with JWT-based authentication, then create, list, view, complete, and delete their own habits — each user can only see and manage habits they own. Completing a habit tracks a streak, based on the habit's frequency (daily, weekly, monthly, or yearly).

Live API: https://habit-tracker-api-8zgs.onrender.com/ — interactive docs at /docs

Frontend: habit-tracker-web, a companion app that consumes this API.

Tech Stack

• FastAPI — web framework and routing
• SQLAlchemy — ORM / database models
• SQLite — database
• JWT auth — via python-jose and passlib (bcrypt password hashing)
• pytest — testing

Setup

From a fresh clone:

# 1. Create and activate a virtual environment
python -m venv venv
source venv/bin/activate       # Windows: venv\Scripts\activate

# 2. Install dependencies
pip install -r requirements.txt

# 3. Set up environment variables
cp .env.example .env
# then open .env and set SECRET_KEY to a real secret value

# 4. Run the server
uvicorn main:app --reload

The API will be available at http://127.0.0.1:8000.

Running Tests

pytest -v

Endpoints

Full interactive docs (Swagger UI) are available at /docs once the server is running.

Method	Path	Description
GET	/	API info
POST	/users/register	Register a new user
POST	/users/login	Log in and receive a JWT access token
POST	/habits	Create a new habit
GET	/habits	List your habits
GET	/habits/{habit_id}	Get a single habit
PATCH	/habits/{habit_id}/complete	Toggle completion for the current period, updates streak
DELETE	/habits/{habit_id}	Delete a habit

All /habits endpoints require a valid JWT access token (obtained via /users/login) sent as a Bearer token.

A habit's frequency is one of daily, weekly, monthly, or yearly. This determines what counts as the "current period" for PATCH /habits/{habit_id}/complete: e.g. for a weekly habit, completing it once anywhere in the ISO week satisfies that week, and the streak only continues if the previous completion fell in the immediately preceding period (day/week/month/year).

Notes on Persistence

This project uses SQLite (habits.db) for simplicity. If deployed on a host with an ephemeral filesystem (e.g. Render's free tier), the database file can be wiped on redeploy or restart, losing all data. For production use, migrate to a persistent database like PostgreSQL.

Known Limitations

• Streak day boundaries use server time. Completion periods are computed from date.today() on the server, which runs in UTC on Render. A user's "day" therefore rolls over at UTC midnight rather than their own local midnight, so a completion made late at night in some timezones could land in the "wrong" day or week. Fine for now; a proper fix would take the user's timezone into account.