Most students build projects that look complete but are difficult to explain or don’t run properly when tested. The issue is not effort, it’s the lack of a clear, connected process. A good placement project should do three things well:

1. It should solve a simple, real problem.
2. It should work end-to-end without breaking.
3. You should be able to explain every part of it.

This guide is designed with that exact goal. If you follow this guide patiently, you will build a fully working backend project that you can confidently present in interviews.

Table of Contents

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Project Overview

People spend money every day but often do not track where it goes. Over time, this leads to confusion about spending habits.

Solution:
You will build a system that allows users to:

1. Record expenses
2. Store them safely
3. View all expenses
4. Filter by category
5. Analyze total and category-wise spending

What you are actually building?
You are building a backend API system. That means:

1. It receives requests (like “add expense”)
2. Processes them
3. Stores data
4. Sends back responses

How the system works?

1. User sends data → “₹200 for food”
2. Your API receives it
3. It stores the data in a database
4. When requested, it returns stored data or summaries

Software Required

Before starting, install the following tools.

1. Python: Python is the programming language used to build the project. It is easy to learn and widely used in backend development.
2. Command Prompt (CMD): CMD is where you will type all commands to create folders, run the project, and install libraries.
3. Flask: Flask is a lightweight framework that helps you create APIs and handle requests.
4. SQLite: SQLite is a simple database that stores your data in a file without needing complex setup.
5. Postman: Postman is used to test your API by sending requests and checking responses.
6. Git and GitHub: Git tracks your code changes, and GitHub stores your project online.
7. Render: Render is used to deploy your project and make it live on the internet.

Step 1: Setting Up the Environment

In this step, you are preparing your system so that your project runs smoothly without errors.
1. Open Command Prompt

Press Windows + R, type cmd, and press Enter

This opens the command line where you will type all commands.
2. Check Python Installation
Type this in CMD:

python --version

This command checks whether Python is installed.
If successful, you will see something like:

Python 3.x.x

If not, install Python and enable “Add to PATH”.
3. Create Project Folder
Now type:

mkdir expense-tracker
cd expense-tracker

This creates your project folder and moves you inside it.
4. Create Virtual Environment
Type:

python -m venv venv

This creates an isolated environment for your project.
5. Activate Virtual Environment
Type:

venv\Scripts\activate

You should now see (venv) in your terminal. This confirms activation.
6. Install Required Libraries
Type:

pip install flask gunicorn

This installs:

Flask for backend
Gunicorn for deployment

Step 2: Create Project File

You are creating the main file where your backend logic will exist.
1. Create file
Type:

notepad app.py

This opens Notepad.
Note:

1. Save file as app.py
2. Make sure it is not saved as .txt

2. Verify
Type:

dir

You should see:

app.py
venv

Step 3: Add Complete Code

You are adding the full backend logic so the application can handle requests, store data, and return results.
Paste the following code into app.py and save it:

from flask import Flask, request, jsonify
import sqlite3

app = Flask(__name__)

def get_db_connection():
    conn = sqlite3.connect("database.db")
    conn.row_factory = sqlite3.Row
    return conn

def init_db():
    conn = get_db_connection()
    cursor = conn.cursor()
    
    cursor.execute("""
    CREATE TABLE IF NOT EXISTS expenses (
        id INTEGER PRIMARY KEY AUTOINCREMENT,
        amount REAL NOT NULL,
        category TEXT NOT NULL,
        date TEXT NOT NULL,
        description TEXT
    )
    """)
    
    conn.commit()
    conn.close()

init_db()

@app.route("/")
def home():
    return "Expense Tracker API is running"

@app.route("/add", methods=["POST"])
def add_expense():
    data = request.get_json()

    if not data:
        return jsonify({"error": "No input data"}), 400

    if not data.get("amount") or not data.get("category") or not data.get("date"):
        return jsonify({"error": "Missing fields"}), 400

    conn = get_db_connection()
    cursor = conn.cursor()

    cursor.execute(
        "INSERT INTO expenses (amount, category, date, description) VALUES (?, ?, ?, ?)",
        (
            float(data["amount"]),
            data["category"],
            data["date"],
            data.get("description", "")
        )
    )

    conn.commit()
    conn.close()

    return jsonify({"message": "Expense added successfully"})

@app.route("/expenses", methods=["GET"])
def get_expenses():
    conn = get_db_connection()
    cursor = conn.cursor()

    cursor.execute("SELECT * FROM expenses")
    rows = cursor.fetchall()

    conn.close()

    return jsonify([dict(row) for row in rows])

@app.route("/expenses/category", methods=["GET"])
def filter_category(category):
    conn = get_db_connection()
    cursor = conn.cursor()

    cursor.execute("SELECT * FROM expenses WHERE category=?", (category,))
    rows = cursor.fetchall()

    conn.close()

    return jsonify([dict(row) for row in rows])

@app.route("/summary", methods=["GET"])
def summary():
    conn = get_db_connection()
    cursor = conn.cursor()

    cursor.execute("SELECT SUM(amount) as total FROM expenses")
    result = cursor.fetchone()

    conn.close()

    return jsonify({"total": result["total"] or 0})

@app.route("/category-summary", methods=["GET"])
def category_summary():
    conn = get_db_connection()
    cursor = conn.cursor()

    cursor.execute("SELECT category, SUM(amount) as total FROM expenses GROUP BY category")
    rows = cursor.fetchall()

    conn.close()

    return jsonify([dict(row) for row in rows])

if __name__ == "__main__":
    app.run(debug=True)

Step 4: Run the Project

You are starting your backend server.
1. In the command prompt, type:

python app.py

This runs your application.
You should see:

Running on http://127.0.0.1:5000/

2. Open your browser and go to:

http://127.0.0.1:5000/ 

You should see:

Expense Tracker API is running

Step 5: Test the API

You are verifying that your backend works correctly. To test API open Postman:
1. Add Expense

POST → /add
{
  "amount": 200,
  "category": "Food",
  "date": "2026-04-13",
  "description": "Lunch"
}

Expected result:

Expense added successfully

2. Get Expenses

GET → /expenses

3. Filter

GET → /expenses/Food

4. Summary

GET → /summary

5. Category Summary

GET → /category-summary

Step 6: Create requirements.txt

You are saving project dependencies for deployment. In the command prompt, type:

pip freeze requirements.txt

Step 7: Deployment

You are making your project live.
1. Initialize Git
In the command prompt, type:

git init
git add .
git commit -m "Initial commit"

2. Push to GitHub
In the command prompt, type:

git remote add origin YOUR_REPO_URL
git push -u origin main

3. On Render
Build:

pip install -r requirements.txt

Start:

gunicorn app:app

Conclusion

This project shows that you can take an idea and turn it into a working system. You set up the environment, built a backend, handled data, tested your APIs, and deployed the application.
That is exactly what recruiters look for, not just code, but the ability to build something complete and explain it clearly.

Frequently Asked Questions

1. Can beginners complete this project?

Yes, every step is explained clearly with expected outcomes.

2. Do I need frontend?

No, backend is enough for most placements.

3. What if my project does not run?

Check each step and ensure outputs match expectations.

4. Is deployment important?

Yes, it shows real-world readiness.

5. How can I improve this project?

Add login, charts, or convert it into a full-stack app.