I'm working on an app that makes use of this in a good way (to add new contacts and remove duplicates with explicit action by the user). While doing some resea

I'm working on an app that makes use of this in a good way (to add new contacts and remove duplicates with explicit action by the user). While doing some research on similar apps, I didn't find a single app that does not give the user an option to not upload the contacts to the app's servers. Basically if use doesn't give this permission, app is useless. I'm hoping the app I build will get a sustainable revenue without needing to uploading all contacts. But in the long run, for contact management apps, there's exponentially more value in handling the contacts data in the cloud, so that its users get the max benefit. But imo any app that's not for contact management (e.g., Facebook etc) should have limited read only access to the contacts data.