Doppi and its creator deeply respect user privacy. Doppi does not collect any personal information, ever.
Doppi operates locally on the user's device, and doesn't access the network unless the user explicitly requests a lyrics fetch, or connects their Last.fm account. Apple may make network connections to App Store services on behalf of Doppi in the context of in-app purchases and subscriptions.
At no point is user data captured or transmitted by Doppi or its bundled systems. Telemetry (analytics) are never collected on general release versions of the app, but they are in beta versions, which the user can manually opt into using.