A complete guide to building modern web applications using Reflex

In the past, building a modern web application means you have to learn front-end (React/JS/HTML/CSS) + back-end (Flask/Django) + API interaction (REST/GraphQL) + deployment logic. Reflex, on the other hand, hopes to simplify these complex technology stacks into a language - Python.

In this article, we will introduce the design philosophy, technical features, project structure, core API, actual development process, and comparison and deployment suggestions with other frameworks.

What is Reflex?

Reflex is an open source framework for building complete front- and back-end web applications in Python.

Its core goals are:

• Let developers write complete web applications using only Python;
• Automatically generate React front-end and FastAPI back-end;
• Zero JavaScript/HTML code, the code is purer and the maintenance cost is lower;
• Supports static deployment, dynamic deployment and SPA construction.

GitHub： /reflex-dev/reflex

Official website:

Why choose Reflex?

Very suitable for:

• Prototyping / Data Display Panel
• Backend management system
• AI WebApp prototype (combined with LangChain and OpenAI)
• I don't want to write a front-end Python engineer!

Installation and Environment Configuration

Installation requirements:

• Python 3.8+
• (Automatic installation dependency)

pip install reflex

Create a project:

reflex init myapp
cd myapp
reflex run

This will open http://localhost:3000 in the browser, and the default homepage will run!

Build your first application

Create a file:

import reflex as rx

class State():
    count: int = 0

    def increment(self):
         += 1

app = ()
app.add_page(
    (
        ("Welcome to Reflex!"),
        ("Count value: "), 
        (),
        ("Click +1", on_click=)
    )
)

run:

reflex run

After clicking the button, the page will respond immediately, showing the new count value. This is responsive state binding.

Core concept analysis

Component system

All UIs are composed of () and are similar to React-like JSX:

(
    ("Hello"),
    ("This is a paragraph"),
    ("Click Me")
)

Common components that support include:

• Text: text, heading, code
• Layout: vstack, hstack, center, grid
• Form: input, textarea, select, checkbox
• Display: image, table, card, modal

Status Management

The core of Reflex is the state-driven UI:

class State():
    name: str = "world"

    def change_name(self, new_name: str):
         = new_name

Reference directly in the component and the system will automatically update.

Routing system

Just one function to add a page:

def index():
    return ("Homepage")

app.add_page(index, route="/")

You can also automatically scan py files in the pages/ folder to automatically generate routes.

Project structure at a glance

myapp/
│
├──           # Application portal
├──           # Status Management
├── pages/                 # Page definition
│   └──     # Automatically map to "/"
├── assets/                          # Static resources
├── .web/                    # Build products (auto-generated)
├──        # Configuration file (title, topic, route)
└──

Advanced Features

Asynchronous state and background tasks

Reflex supports async def state operations, which are very suitable for calling third-party APIs, AI models, etc.:

class State():
    result: str = ""

    async def fetch_data(self):
        import httpx
        async with () as client:
            res = await ("")
             = 

Front-end event binding

(on_change=State.set_name)
("submit", on_click=)

Combination operations are also supported:

on_click=[, ]

Integrate with database/backend frameworks

Reflex itself is based on FastAPI and can introduce ORMs, such as SQLModel and Tortoise ORM:

from sqlmodel import SQLModel, create_engine

engine = create_engine("sqlite:///")

You can call your own database logic through customization to fully control the backend.

Reflex vs Streamlit vs Dash

Summary: Reflex is more like a "real web framework" than a simple data display tool.

Reflex application deployment method

Local build (recommended production use)

reflex export

Generate .web folders for deployment to:

• Vercel/Netlify (static page)
• Docker build backend (API server)

You can also use the official build command directly:

reflex deploy

Supports binding of custom domain names and deploying using CI/CD.

Docker deployment

FROM python:3.10

WORKDIR /app
COPY . .
RUN pip install reflex
RUN reflex export

CMD ["reflex", "run", "--env", "production"]

Reflex’s limitations and future prospects

Current restrictions:

• It is not as flexible as native React for complex interaction logic;
• SEO support is weak (SPA nature);
• Internationalization (i18n) and multilingual are not supported yet;
• It integrates less with front-end libraries (such as chart libraries such as ECharts need to be manually introduced).

Development direction:

• Component customization will be supported soon (write JSX + Py bindings)
• Official plan to integrate AI components and chart libraries
• Enhanced compatibility with LangChain, Pandas, Plotly

Conclusion

Reflex is iterating at an amazing speed with the goal of becoming the "" in the Python world. if you:

Is a Python developer but don't want to write front-end;

Hope to quickly build modern web applications;

AI applications, prototypes, and background management systems are being developed...

That Reflex is one of the most worth trying new tools.

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