The best way of protecting users' data is to not collect it in the first place.
No data is send to wemp or mecking.net servers at any time, unless the user explicitly requests it.
Bookmarks and the history is stored in a private database in iCloud and protected by Apple's CloudKit framework. The data can only be accessed by the user who created it.
iCloud is a service by Apple Inc.
In the case of software crashes, a report of the incident (crash log) gets submitted to Fabric.io/Crashlytics. Those reports don't contain any personal data. Additionally Crashlytics counts App launches to measure the relative stability of the apps.
Fabric.io/Crashlytics is a service by Twitter Inc.