Kaiku is an on-device text-to-speech desktop app. Its optional Twitch integration connects to a backend service that acts purely as a relay.
When you connect your Twitch account we store, on the backend, your Twitch user id and login and an OAuth access/refresh token pair (encrypted at rest). These let the service subscribe to your channel's events (chat, channel-point redemptions, cheers, subscriptions, follows) on your behalf.
Incoming Twitch events are relayed in real time to your own Kaiku desktop app, which reads selected messages aloud. Events are not persisted on the backend and are not shared with third parties.
You can export or permanently delete everything the backend stores about you at any time from within the Kaiku app (Disconnect / Delete my data), which also revokes the connection.