FastHTML Has a Free API: Build Web Apps in Pure Python — No JavaScript Required

#python #webdev #fasthtml #htmx

Django templates. Flask + Jinja. FastAPI + React. What if you just... wrote Python?

What Is FastHTML?

FastHTML lets you build complete web applications in pure Python. No templates. No JavaScript. No frontend build step. HTML elements are Python functions.

from fasthtml.common import *

app, rt = fast_app()

@rt("/")
def get():
    return Titled("My App",
        H1("Hello World!"),
        P("This is a complete web page."),
        Button("Click me", hx_get="/clicked", hx_target="#result"),
        Div(id="result")
    )

@rt("/clicked")
def get():
    return P("You clicked the button!")

serve()

python app.py
# Running at http://localhost:5001

That's a complete interactive web app. In Python. With htmx-powered interactivity.

HTML as Python

# Every HTML element is a Python function
page = Html(
    Head(Title("My Page")),
    Body(
        Nav(
            A("Home", href="/"),
            A("About", href="/about"),
        ),
        Main(
            H1("Welcome"),
            Ul(
                Li("Item 1"),
                Li("Item 2"),
                Li("Item 3"),
            ),
            Form(
                Input(name="email", type="email", placeholder="your@email.com"),
                Button("Subscribe", type="submit"),
                hx_post="/subscribe",
                hx_target="#message"
            ),
            Div(id="message")
        )
    )
)

Database Integration

app, rt, todos, Todo = fast_app(
    'todos.db',
    todo=str,
    done=bool,
    pk='id'
)

@rt("/")
def get():
    items = todos()
    return Titled("Todos",
        Ul(*[Li(t.todo, " ✓" if t.done else "") for t in items]),
        Form(
            Input(name="todo", placeholder="New todo..."),
            Button("Add"),
            hx_post="/add", hx_target="ul", hx_swap="beforeend"
        )
    )

@rt("/add")
def post(todo: str):
    new = todos.insert(Todo(todo=todo, done=False))
    return Li(new.todo)