← Back to DevBytes
Go July 09, 2026 14 min read

Flet vs Django vs FastAPI: Framework Comparison

Introduction: Understanding the Landscape

Modern Python web development presents developers with a fascinating dilemma: choose a framework that aligns perfectly with your project's unique requirements. Flet, Django, and FastAPI represent three fundamentally different philosophies in the Python ecosystem. Flet brings Flutter's UI capabilities to Python for desktop and web apps. Django offers a batteries-included, full-stack web framework with decades of maturity. FastAPI delivers high-performance APIs with automatic OpenAPI documentation. This tutorial dissects each framework, provides hands-on code examples, and guides you toward making an informed architectural decision.

What is Flet?

🚀 Deploy your AI agent in 10 minutes

Managed Hermes hosting. Zero DevOps. 100M tokens/mo included.

Try it free →

Flet is a relatively new Python framework that enables developers to build interactive, multi-platform applications—including web, desktop, and mobile—using a Flutter-inspired widget model. You write Python code, and Flet compiles it into Flutter widgets rendered in the browser or as a native desktop app. There's no need to write a single line of JavaScript, HTML, or CSS. Flet excels at data-heavy internal tools, dashboards, and real-time collaborative applications where the UI is generated server-side and streamed to the client over WebSockets.

Core Concepts

Flet Code Example: Interactive Counter App

import flet as ft

def main(page: ft.Page):
    page.title = "Flet Counter Demo"
    page.vertical_alignment = ft.MainAxisAlignment.CENTER
    page.horizontal_alignment = ft.CrossAxisAlignment.CENTER
    
    # Counter state
    counter = ft.Text("0", size=50, weight=ft.FontWeight.BOLD)
    
    def increment_click(e):
        current = int(counter.value)
        counter.value = str(current + 1)
        page.update()
    
    def decrement_click(e):
        current = int(counter.value)
        counter.value = str(current - 1)
        page.update()
    
    def reset_click(e):
        counter.value = "0"
        page.update()
    
    # UI Layout
    page.add(
        ft.Row(
            [
                ft.IconButton(ft.icons.REMOVE, on_click=decrement_click),
                counter,
                ft.IconButton(ft.icons.ADD, on_click=increment_click),
            ],
            alignment=ft.MainAxisAlignment.CENTER,
        ),
        ft.ElevatedButton("Reset", on_click=reset_click),
    )

ft.app(target=main)

This complete example demonstrates Flet's core workflow: define controls, attach event handlers, mutate state, and call page.update() to push changes to the UI. The same code runs as a web app, desktop window, or PWA with zero modifications.

What is Django?

Django is a high-level, full-stack Python web framework that follows the "batteries-included" philosophy. It provides an ORM, authentication system, admin interface, form handling, template engine, and more—all out of the box. Django powers some of the largest websites on the internet, including Instagram, Pinterest, and Mozilla. It's built around the MVT (Model-View-Template) architectural pattern and emphasizes rapid development, clean design, and security by default.

Core Concepts

Django Code Example: Complete Task Manager API

# models.py
from django.db import models

class Task(models.Model):
    title = models.CharField(max_length=200)
    description = models.TextField(blank=True)
    completed = models.BooleanField(default=False)
    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)
    
    def __str__(self):
        return self.title

# admin.py
from django.contrib import admin
from .models import Task

@admin.register(Task)
class TaskAdmin(admin.ModelAdmin):
    list_display = ['title', 'completed', 'created_at']
    list_filter = ['completed']

# views.py
from django.shortcuts import render, redirect, get_object_or_404
from django.views.decorators.http import require_http_methods
from .models import Task

@require_http_methods(["GET", "POST"])
def task_list(request):
    if request.method == "POST":
        title = request.POST.get("title")
        if title:
            Task.objects.create(title=title)
        return redirect('task_list')
    tasks = Task.objects.all().order_by('-created_at')
    return render(request, 'tasks/task_list.html', {'tasks': tasks})

@require_http_methods(["POST"])
def toggle_task(request, pk):
    task = get_object_or_404(Task, pk=pk)
    task.completed = not task.completed
    task.save()
    return redirect('task_list')

@require_http_methods(["POST"])
def delete_task(request, pk):
    task = get_object_or_404(Task, pk=pk)
    task.delete()
    return redirect('task_list')

# urls.py
from django.urls import path
from . import views

urlpatterns = [
    path('', views.task_list, name='task_list'),
    path('toggle//', views.toggle_task, name='toggle_task'),
    path('delete//', views.delete_task, name='delete_task'),
]

And the accompanying template file:

<!-- templates/tasks/task_list.html -->
<!DOCTYPE html>
<html>
<head>
    <title>Task Manager</title>
    <style>
        .completed { text-decoration: line-through; color: #888; }
    </style>
</head>
<body>
    <h1>Task Manager</h1>
    <form method="post">
        {% csrf_token %}
        <input type="text" name="title" placeholder="New task...">
        <button type="submit">Add</button>
    </form>
    <ul>
        {% for task in tasks %}
            <li class="{% if task.completed %}completed{% endif %}">
                {{ task.title }}
                <form method="post" action="{% url 'toggle_task' task.pk %}" style="display:inline">
                    {% csrf_token %}
                    <button>Toggle</button>
                </form>
                <form method="post" action="{% url 'delete_task' task.pk %}" style="display:inline">
                    {% csrf_token %}
                    <button>Delete</button>
                </form>
            </li>
        {% empty %}
            <li>No tasks yet!</li>
        {% endfor %}
    </ul>
</body>
</html>

This example showcases Django's integrated stack: models define the schema, views handle business logic, the admin provides instant CRUD management, and templates render HTML with CSRF protection built-in. The entire application works with just a few files and zero external dependencies beyond Django itself.

What is FastAPI?

FastAPI is a modern, high-performance web framework for building REST APIs and microservices with Python 3.7+. It leverages Python's type hints to provide automatic request validation, serialization, and interactive OpenAPI documentation. Built on Starlette (for web handling) and Pydantic (for data validation), FastAPI achieves near-Node.js performance levels while maintaining Python's developer-friendly syntax. It's ideal for backend APIs consumed by React/Vue frontends, mobile apps, or third-party integrations.

Core Concepts

FastAPI Code Example: Full REST API with Database

# main.py
from fastapi import FastAPI, HTTPException, Depends, status
from sqlalchemy import create_engine, Column, Integer, String, Boolean, DateTime
from sqlalchemy.orm import sessionmaker, declarative_base, Session
from pydantic import BaseModel, Field
from datetime import datetime
from typing import Optional, List

# Database setup
DATABASE_URL = "sqlite:///./tasks.db"
engine = create_engine(DATABASE_URL, connect_args={"check_same_thread": False})
SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
Base = declarative_base()

# SQLAlchemy Model
class TaskModel(Base):
    __tablename__ = "tasks"
    id = Column(Integer, primary_key=True, index=True)
    title = Column(String(200), nullable=False)
    description = Column(String, default="")
    completed = Column(Boolean, default=False)
    created_at = Column(DateTime, default=datetime.utcnow)
    updated_at = Column(DateTime, default=datetime.utcnow, onupdate=datetime.utcnow)

Base.metadata.create_all(bind=engine)

# Pydantic Schemas
class TaskCreate(BaseModel):
    title: str = Field(..., min_length=1, max_length=200)
    description: Optional[str] = Field("", max_length=1000)
    completed: bool = False

class TaskResponse(BaseModel):
    id: int
    title: str
    description: str
    completed: bool
    created_at: datetime
    updated_at: datetime
    
    class Config:
        orm_mode = True  # Enable ORM-to-Pydantic conversion

class TaskUpdate(BaseModel):
    title: Optional[str] = Field(None, min_length=1, max_length=200)
    description: Optional[str] = None
    completed: Optional[bool] = None

# FastAPI App
app = FastAPI(title="Task Manager API", version="1.0.0")

# Dependency: get a database session per request
def get_db():
    db = SessionLocal()
    try:
        yield db
    finally:
        db.close()

@app.post("/tasks", response_model=TaskResponse, status_code=status.HTTP_201_CREATED)
async def create_task(task: TaskCreate, db: Session = Depends(get_db)):
    """Create a new task with title and optional description."""
    db_task = TaskModel(**task.dict())
    db.add(db_task)
    db.commit()
    db.refresh(db_task)
    return db_task

@app.get("/tasks", response_model=List[TaskResponse])
async def list_tasks(
    completed: Optional[bool] = None,
    skip: int = 0,
    limit: int = 100,
    db: Session = Depends(get_db)
):
    """Retrieve tasks with optional filtering and pagination."""
    query = db.query(TaskModel)
    if completed is not None:
        query = query.filter(TaskModel.completed == completed)
    tasks = query.order_by(TaskModel.created_at.desc()).offset(skip).limit(limit).all()
    return tasks

@app.get("/tasks/{task_id}", response_model=TaskResponse)
async def get_task(task_id: int, db: Session = Depends(get_db)):
    """Fetch a single task by its ID."""
    task = db.query(TaskModel).filter(TaskModel.id == task_id).first()
    if task is None:
        raise HTTPException(status_code=404, detail="Task not found")
    return task

@app.patch("/tasks/{task_id}", response_model=TaskResponse)
async def update_task(task_id: int, updates: TaskUpdate, db: Session = Depends(get_db)):
    """Partially update a task's fields."""
    task = db.query(TaskModel).filter(TaskModel.id == task_id).first()
    if task is None:
        raise HTTPException(status_code=404, detail="Task not found")
    update_data = updates.dict(exclude_unset=True)
    for key, value in update_data.items():
        setattr(task, key, value)
    task.updated_at = datetime.utcnow()
    db.commit()
    db.refresh(task)
    return task

@app.delete("/tasks/{task_id}", status_code=status.HTTP_204_NO_CONTENT)
async def delete_task(task_id: int, db: Session = Depends(get_db)):
    """Permanently remove a task."""
    task = db.query(TaskModel).filter(TaskModel.id == task_id).first()
    if task is None:
        raise HTTPException(status_code=404, detail="Task not found")
    db.delete(task)
    db.commit()
    return None

This comprehensive FastAPI example demonstrates automatic request validation via Pydantic, dependency injection for database sessions, async path operations, and full CRUD functionality. Visiting /docs after running this code reveals an interactive Swagger UI where every endpoint can be tested directly in the browser—no Postman required.

Why the Comparison Matters

Choosing the wrong framework for your project can multiply development time, cripple performance, or force painful architectural rewrites mid-project. Each framework in this comparison targets a fundamentally different use case:

Understanding these distinctions prevents the common mistake of forcing a framework into a role it wasn't designed for—like using Django for a real-time WebSocket dashboard (possible but cumbersome) or FastAPI for a content-heavy CMS with admin panels (possible but requires extensive custom tooling).

Detailed Comparison: Side by Side

Architecture & Paradigm

Learning Curve

Performance & Concurrency

Database & ORM

Authentication & Security

Frontend Integration

When to Use Each Framework

Choose Flet When:

Choose Django When:

Choose FastAPI When:

Best Practices

Flet Best Practices

Django Best Practices

FastAPI Best Practices

Conclusion

Flet, Django, and FastAPI occupy distinct niches in the Python web ecosystem, and the "best" framework depends entirely on what you're building. Flet revolutionizes internal tool and dashboard development by collapsing the frontend-backend boundary into a single Python codebase with Flutter-quality rendering. Django remains the gold standard for full-stack web applications where server-rendered HTML, content management, authentication, and an admin interface are non-negotiable requirements. FastAPI dominates the API-first landscape with its type-driven development model, exceptional async performance, and automatic documentation that doubles as a live API playground.

The practical code examples in this tutorial—from Flet's reactive counter to Django's task manager with admin, to FastAPI's fully documented REST API—demonstrate that each framework excels in its intended domain. Your decision should flow from your project's core requirements: UI generation model, rendering strategy, performance profile, and team composition. There is no universal winner, only the right tool for the job at hand. Understanding all three frameworks expands your architectural vocabulary and equips you to choose confidently when the next project begins.

🚀 Need a reliable AI agent for your project?

Deploy Hermes Agent in 10 minutes. Managed hosting, zero DevOps.

Get Started — $23.99/mo
← Back to all articles