With Duets.fm, all your songs, favorite singers, downloads and other customizations, stay on your device and are never sent to a server. While this gives you great privacy, it also means that duets.fm data is not backed up. If you buy a new phone and would like to move all your customizations to the new phone, you would need a cloud backup service like iCloud or Google One. When you use a cloud backup service, the service will give you the option to copy the apps and data from one device to another. This option will move all the customizations you made in duets.fm from an old device, to the new device. The base data for the app would occupy only a few megabytes (about 10 MB for 30,000 songs) and would be a quick restore on the new device. But if you have a lot of downloaded songs, you might be using gigabytes of storage and the restore can take a long time. For Android users, please note that only songs downloaded to the internal storage would be backed up.