Decide between Twitch EventSub webhook and WebSocket transport based on an app's subscription volume and hosting model

Steps

1. Choose webhook transport when you need to scale to many subscriptions across many channels/users: webhooks use app access tokens and support a much higher max_total_cost ceiling than WebSocket.
2. Choose WebSocket transport for single-session, per-user integrations (like a local overlay or extension) where you don't want to run a public HTTPS endpoint: WebSocket subscriptions are tied to a user access token.
3. Note the WebSocket constraints: a small number of WebSocket connections with enabled subscriptions per client/user token pair, a per-connection subscription count cap, and a low max_total_cost per connection.
4. For webhook transport, stand up a publicly reachable HTTPS callback endpoint, verify the Twitch-Eventsub-Message-Signature header on every notification, and respond within Twitch's timeout window.
5. For WebSocket transport, maintain the persistent connection, respond to keepalive/reconnect messages, and re-subscribe via the API after a reconnect_url-driven reconnection.