channel-box

channel-box is a lightweight async package for Starlette and FastAPI that allows you to send messages to named WebSocket channels (groups) from any part of your backend code.

It is designed for simple real-time communication patterns without external brokers or heavy abstractions.

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Features

• Named WebSocket channels (groups)
• Broadcast messages to all connected clients
• Send messages from any part of the backend
• Optional message history per group
• Automatic cleanup of disconnected and expired connections
• Fully async, compatible with FastAPI & Starlette
• Zero external infrastructure (no Redis, no RabbitMQ)

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Typical use cases

• Group chats
• Backend notifications
• Alerts for user groups
• Real-time status updates
• Internal dashboards

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Installation

pip install channel-box

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Basic usage example

WebSocket endpoint

import json
from starlette.endpoints import WebSocketEndpoint
from channel_box import Channel, ChannelBox


class WsChatEndpoint(WebSocketEndpoint):

    async def on_connect(self, websocket):
        group_name = websocket.query_params.get("group_name")
        await websocket.accept()

        if not group_name:
            return

        channel = Channel(
            websocket=websocket,
            expires=60 * 60,
            payload_type="json",
        )

        await ChannelBox.add_channel_to_group(
            channel=channel,
            group_name=group_name,
        )

    async def on_receive(self, websocket, data):
        payload = json.loads(data)

        message = payload.get("message")
        username = payload.get("username")

        if not message:
            return

        group_name = websocket.query_params.get("group_name")

        if group_name:
            await ChannelBox.group_send(
                group_name=group_name,
                payload={
                    "username": username,
                    "message": message,
                },
                save_history=True,
            )

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Send messages from anywhere in backend

from channel_box import ChannelBox

await ChannelBox.group_send(
    group_name="MyChat",
    payload={
        "username": "System",
        "message": "Hello from backend",
    },
    save_history=True,
)

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Groups management

Get active groups

groups = await ChannelBox.get_groups()
print(groups)

Flush all groups

await ChannelBox.flush_groups()

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Message history

Get history

history = await ChannelBox.get_history()
print(history)

Flush history

await ChannelBox.flush_history()

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Cleanup expired connections

await ChannelBox.clean_expired()

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NGINX WebSocket configuration

If you use NGINX as a reverse proxy, make sure WebSocket support is enabled:

http://nginx.org/en/docs/http/websocket.html

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Uvicorn

pip install uvicorn[standard]

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Full working example

https://github.com/Sobolev5/channel-box/tree/master/example

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Tests

pytest

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Repository

https://github.com/Sobolev5/channel-box

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License

MIT