Beginner Python Project: Build a Command-Line To-Do List App

ByAhmed Nabil March 7, 2026February 3, 2026

3D visualization of a holographic checklist inside a command line terminal, representing a Python To-Do List project.

This classic Python To-Do List Project is one that combines all your fundamental skills: loops, functions, lists, and file handling.

We’ll build a simple program that lets a user manage a tasks.txt file.

Step 1: The Main Loop

We need a while True loop to keep the program running until the user types “quit”.

def main():
    while True:
        print("\n--- To-Do List ---")
        print("1. View Tasks")
        print("2. Add Task")
        print("3. Remove Task")
        print("4. Quit")
        choice = input("Enter choice: ")

        if choice == '1':
            view_tasks()
        elif choice == '2':
            add_task()
        elif choice == '3':
            remove_task()
        elif choice == '4':
            break
        else:
            print("Invalid choice.")

if __name__ == "__main__":
    main()

Step 2: Add and View Tasks

We need to read from and write to our file.

# (Place this above main())
TASKS_FILE = "tasks.txt"

def view_tasks():
    try:
        with open(TASKS_FILE, "r") as f:
            tasks = f.readlines()
            if not tasks:
                print("No tasks found.")
            for i, task in enumerate(tasks):
                print(f"{i+1}. {task.strip()}")
    except FileNotFoundError:
        print("No tasks found.")

def add_task():
    task = input("Enter new task: ")
    # Use 'a' (append) mode
    with open(TASKS_FILE, "a") as f:
        f.write(task + "\n")
    print("Task added.")

Step 3: Remove Task

This is the trickiest part. We have to read all lines into a list, remove one, and then re-write the entire file.

def remove_task():
    view_tasks()
    try:
        task_num = int(input("Enter task number to remove: "))
        with open(TASKS_FILE, "r") as f:
            tasks = f.readlines()
        
        if 1 <= task_num <= len(tasks):
            # Remove the task (task_num is 1-based, list is 0-based)
            tasks.pop(task_num - 1)
            
            # Write the NEW list back to the file
            with open(TASKS_FILE, "w") as f:
                f.writelines(tasks)
            print("Task removed.")
        else:
            print("Invalid task number.")
    except (ValueError, FileNotFoundError):
        print("Invalid input.")

Ahmed Nabil

Python Engineer and the founder of Python Pro Hub. With a focus on modern data science (Polars), backend architecture (FastAPI/Django), and automation, builds production-grade tutorials designed to take developers from absolute beginners to advanced software engineers.