Timebox always respects your privacy:
Unlike many apps, none of the data in the Timebox app is ever retained by or visible to our company, Pepper Networks, LLC.
All of the data that's in the Timebox app is either on your own device (iPhone or iPad) or in your own personal iCloud account. In other words, it’s only ever visible to you or people that you invite to share your data (i.e., to a group gallery).
If you delete the Timebox app from your device, you’ll delete the copy of the data that’s on your device. If you delete your personal iCloud account, you’ll also delete the copy that you have in iCloud.
For privacy, security and longevity, Timebox uses your iCloud storage for all synching and sharing. Also, Timebox uses "links" to the photos & videos in your Photos so it never makes any copies nor uploads any until you explicitly chose to Share them with other people.