If you’ve ever wanted to build a modern desktop app using only Python, without writing HTML, CSS, or JavaScript, then Flet is one of the easiest ways to get started.

In this article, we’ll build a simple Notes App using Python and Flet. The application will allow users to:

• Add notes

• Delete notes

• Store notes permanently using JSON

• View notes in a clean UI

By the end, you’ll understand how Python can be used to build real GUI applications.

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What is Flet?

Flet is a Python framework that allows you to build Flutter-style UI applications using only Python.

With Flet you can create:

• Desktop apps

• Web apps

• Mobile apps

All from a single Python codebase.

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Install Requirements

First install Flet:

pip install flet

Create a new file called:

main.py

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Step 1: Import Required Libraries

import flet as ft
import json
import os

• Flet → Builds the UI

• json → Stores notes permanently

• os → Checks if the notes file exists

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Step 2: Create Data Storage

We will store notes inside a JSON file.

DATA_FILE = "notes.json"

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Step 3: Load Saved Notes

def load_notes():
    if not os.path.exists(DATA_FILE):
        return []
    with open(DATA_FILE, "r") as f:
        return json.load(f)

This function loads notes when the app starts.

If the file doesn’t exist yet, it simply returns an empty list.

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Step 4: Save Notes

def save_notes(notes):
    with open(DATA_FILE, "w") as f:
        json.dump(notes, f, indent=4)

Whenever a note is added or deleted, the updated list is saved to the JSON file.

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Step 5: Build the Main App

def main(page: ft.Page):
    page.title = "Proxlight Notes App"
    page.theme_mode = ft.ThemeMode.LIGHT
    page.padding = 20
    page.scroll = ft.ScrollMode.AUTO

Here we configure the application window.

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Step 6: Create the Notes Input

note_input = ft.TextField(
    hint_text="Write your note here...",
    multiline=True,
    expand=True,
    min_lines=3,
)

This input box allows users to type notes.

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Step 7: Display Notes

notes_column = ft.Column(spacing=10)

Each note will be displayed inside this vertical layout.

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Step 8: Add Notes Function

def add_note(e):
    text = note_input.value.strip()
    if text == "":
        return
    notes.append(text)
    save_notes(notes)
    note_input.value = ""
    refresh_notes()

This function:

1. Reads the input

2. Adds the note

3. Saves it

4. Updates the UI

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Step 9: Delete Notes

def delete_note(index):
    notes.pop(index)
    save_notes(notes)
    refresh_notes()

Each note has a delete button attached to it.

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Step 10: Launch the App

ft.app(target=main)

This starts the Flet application.

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Final Result

You now have a working Notes App built completely with Python.

Features include:

• Clean UI

• Persistent storage

• Add and delete notes

• Beginner-friendly code

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Full Source Code

You can find the complete project on GitHub:

👉 https://github.com/Proxlight/Notepad-using-flet.git

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Watch the Full Video Tutorial

I also created a step-by-step video explaining how this app is built.

📺 Watch here:

👉 https://youtu.be/ZOLWzioqr50

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Why This Project Is Useful

Building projects like this helps you learn:

• Python GUI development

• File handling with JSON

• UI design with Flet

• Real-world application structure

If you’re learning Python, small projects like this are the fastest way to improve.

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Final Thoughts

Flet is quickly becoming one of the easiest frameworks for building cross-platform applications with Python.

Instead of learning multiple languages, you can create desktop, web, and mobile apps using only Python.

If you enjoyed this project, consider exploring:

• To-Do apps

• Markdown note editors

• Task managers

• Database-powered apps

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