fastsyftbox

Build offline-first Python apps with FastAPI and SyftBox — FAST.

🚀 Features

• Build local admin UIs with FastAPI.
• Build delay-tolerant UIs/APIs using SyftEvents.
• Keep private data offline with SyftBox HTTP over RPC.
• Builtin JS SDK with fetch compatible syntax
• Debug APIs with a built-in Postman-style interface.

🔧 Purpose

How can you build a web app that runs on your own device, without uploading data to the cloud?

With SyftBox, you can:

• Run a webserver anywhere that can go offline and keep functioning when it comes back online.
• Access your data even when offline or when your laptop lid is closed.

⚡ Quick Start

Install with uv and create your app:

uvx fastsyftbox version
uvx fastsyftbox create app test

To start in hot-reloading more:

cd test
./run.sh

This generates a sample FastAPI app in app.py:

app = FastSyftBox(
    app_name=app_name,
    syftbox_endpoint_tags=[
        "syftbox"
    ],  # endpoints with this tag are also available via Syft RPC
    include_syft_openapi=True,  # Create OpenAPI endpoints for syft-rpc routes
)


# normal fastapi
@app.get("/", response_class=HTMLResponse)
def root():
    return HTMLResponse("<html><body><h1>Welcome to {app_name}</h1>")


# build a model with pydantic
class MessageModel(BaseModel):
    message: str
    name: str | None = None

# make syftbox rpc endpoints easily
# syft://{datasite}/app_data/{app_name}/rpc/hello
@app.post("/hello", tags=["syftbox"])
def hello_handler(request: MessageModel):
    print("got request", request)
    response = MessageModel(message=f"Hi {request.name}", name="Bob")
    return response.model_dump_json()

# Debug your RPC endpoints in the browser
app.enable_debug_tool(
    endpoint="/hello",
    example_request=str(MessageModel(message="Hello!", name="Alice").model_dump_json()),
    publish=True,
)

HTTP / JS

Vanilla JS fetch:

const url = "http://somewebsite.com/api"
const request = await fetch(url, {
    method: 'POST',
    headers,
    body
});

Becomes syftFetch:

const syftUrl = "syft://madhava@openmined.org/app_data/fastsyftbox/rpc/hello"
const request = await syftFetch(syftUrl, {
    method: 'POST',
    headers,
    body
});

Under the hood:

• Translates to the correct HTTP request
• Adds syft-x headers
• Waits for queued response
• Polls future until completed

What is SyftBox?

SyftBox is a new platform for building privacy-preserving applications and experiences that work over the internet without uploading your data. Instead of sending your data to a server, SyftBox lets you run powerful AI and analytics locally or in trusted environments, so your personal information stays private and secure.

Read more about SyftBox here

🧱 Your Dependencies

Add any Python dependencies to requirements.txt and run.sh will install them fresh every run.

🧪 RPC Debug Tool

Its like Postman but for SyftBox RPC.

A built-in HTML/JS tool helps you debug your HTTP over RPC endpoints. To enable:

app.enable_debug_tool(
    endpoint="/hello",
    example_request=str(MessageModel(message="Hello!", name="Alice").model_dump_json()),
    publish=True,
)

🧭 Construct syft:// RPC URLs

🎯 Configure custom headers

🔍 View real-time responses

Then visit either: http://localhost:${SYFTBOX_ASSIGNED_PORT}/rpc-debug or if you have publish=True https://syftbox.net/datasites/{{ email }}/public/{{ app_name }}/rpc-debug.html

📥 SyftBox App Install via GitHub

syftbox app install GITHUB_URL

This executes run.sh and binds your app to a random port: http://localhost:${SYFTBOX_ASSIGNED_PORT}

📚 Example fastsyftbox Apps

• 🎬 YouTube Wrapped