Stario
Craft realtime hypermedia apps that are a joy to write and ship.

Documentation · Source

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Stario is a small Python framework for enjoyable realtime hypermedia apps. It helps you build web apps where HTTP, HTML, and streaming stay visible in your code. Handlers are plain async functions; routes are registered explicitly; responses go through a dedicated writer. When the UI needs live updates, you can add Datastar and Relay without throwing away the same request/response mental model. The realtime tiles tutorial walks through the full pattern end to end.

Full guides, API reference, and tutorials live at stario.dev. This page is a short orientation for people landing on the repository.

Where Stario fits

Stario is an asyncio-native HTTP stack: you write async handlers and register routes on an App, and the stario CLI runs a built-in HTTP server (TCP or a Unix domain socket). It is not an ASGI application you mount in Uvicorn or Hypercorn; wiring goes through the bootstrap hook, Context, and Writer instead.

Requirements

Python 3.14 or newer is required. The package tracks current Python and the standard library (including APIs the framework builds on) rather than supporting older runtimes.

uvloop (optional): Stario defaults to the stdlib asyncio loop. For a faster event loop on Linux/macOS, install the optional extra and set STARIO_LOOP=uvloop:

uv add "stario[uvloop]"
# or: pip install "stario[uvloop]"

Then run with STARIO_LOOP=uvloop stario serve main:bootstrap (or stario watch). uvloop is not supported on Windows.

Quick start

From an example

Clone the repo (or copy an example directory) and run:

git clone https://github.com/bobowski/stario.git
cd stario/examples/tiles
uv sync
uv run stario watch main:bootstrap

See examples/ for tiles (recommended), hello-world, and chat-room (multi-file layout).

Manual setup

uv init my-app   # creates a new uv project (pyproject, layout)
cd my-app
uv add stario

Put this in main.py:

import stario.responses as responses
from stario import App, Context, Span, UrlPath, Writer


async def home(c: Context, w: Writer) -> None:
    responses.text(w, "Hello from Stario")


HOME = UrlPath("/")

async def bootstrap(app: App, span: Span):
    span.attr("app.name", "example")
    app.get(HOME, home)
    yield

uv run stario watch main:bootstrap

Install with pip install stario if you are not using uv. During startup, bootstrap runs until its single yield: register routes and attach attributes to span before yield; put teardown after yield when needed. Use stario watch in development so the process reloads when files change; use stario serve for a normal long-running server without reload. Server runtime policy (STARIO_HOST, STARIO_PORT, STARIO_TRACER, and related vars) is configured through environment variables — see stario serve --help (Stario does not load .env files; export vars in your shell or use your own dotenv tooling). See Getting started for project layout. For containers, TLS, and production-oriented setup, see Deployment: Containers, TLS, and safe releases.

What you get

• Explicit wiring: async-generator bootstrap(app, span) with a single yield, UrlPath constants, no hidden registration.
• Sharp primitives: Context for the request, Writer for the response, HTML/SVG trees via stario.markup, telemetry via span.
• Static assets: AssetManifest for fingerprinted URLs, StaticAssets(manifest).register(app) in bootstrap.
• Hypermedia by default: HTML and SSE are first-class; realtime layers are optional when the product needs them.
• Observable runs: spans for startup and requests are part of how you structure apps, not an afterthought.

What Stario is not

No bundled ORM, admin UI, or plugin discovery system. Databases, auth, and brokers stay in your code or thin adapters; the framework stays a focused HTTP and hypermedia core.

Releases

Version history and upgrade notes live in CHANGELOG.md.

Contributing

From stario/:

uv sync
uv run ruff check .
uv run ruff format --check .
uv run pyright
uv run pytest

Before committing:

uv run ruff check . --fix
uv run ruff format .