capnweb + Workers

WebSocket RPC from browser to worker to Durable Objects

A reference app showing how capnweb can route all communication over a single WebSocket — including TanStack Start server functions, direct RPC methods, and multiplexed Durable Object connections with hibernation support.

Dice Roller

Worker RPC + server functions

Color Palette

Color naming + analysis

ASCII Zoo

ASCII art + animal facts

DO Multiplexing

Counter + reactions with hibernation

HD-2D Scene

WebGPU diorama + LPC sprites

Architecture

Browser

React app

capnweb RPC session

wsFetch for server functions

WebSocket

↔

/api/ws

↕

Cloudflare Worker

CoreRpcRoot .fetch() .connectCounter() ...

TanStack Start handler

DO root stubs #doRoots

WebSocket

↔

hibernatable

↕

Durable Objects

SharedCounterDO

SharedReactionBoardDO

hibernation + capnweb RPC

Server functions

TanStack Start createServerFn calls are serialized as Request objects and sent over the WebSocket via CoreRpcRoot.fetch().

Direct RPC

Methods like rollDice() and banner() run directly on the worker. No HTTP round-trip, no TanStack Start overhead.

DO multiplexing

Worker opens capnweb sessions to DOs over hibernating WebSockets. Child capability stubs are proxied to the browser automatically.