Developing with MEDKit

After installing MEDKit, initialize one SDK instance per extension page and wait for it to load before calling backend methods.

import Muxy from "@muxy/extensions-js";
Muxy.setup({ clientID: import.meta.env.VITE_CLIENT_ID });
const medkit = new Muxy.SDK();
await medkit.loaded();

const state = await medkit.getAllState();
console.log(state);

Choose the right API

Need	API	Guide
Persistent extension, channel, or viewer data	State methods	Extension and viewer state
Broadcaster or extension settings	Config methods	Configuration data
Live messages between open clients	send and listen	Simple extension
Large-audience counters and rankings	Aggregation methods	Data aggregation
Local Twitch identity/role simulation	DebuggingOptions	User simulation
Twitch Helix helpers	TwitchClient	Twitch API

State is durable; a live message is not. For interfaces that must recover after refresh, persist the latest value first and then send a message to active clients.

Handle failures explicitly

MEDKit methods return promises. Surface initialization and request failures in both logs and the UI, and never assume a write succeeded before its promise resolves.

try {
  await medkit.setChannelState({ round: 4 });
  status.textContent = "Saved";
} catch (error) {
  console.error(error);
  status.textContent = "Save failed";
}

See Troubleshooting for environment, role, and token checks.