Why don't you offer your own cloud sync solution?

Mac app first

Some sync capabilities mentioned here, such as Merge sync and Todoist, are currently available in 2Do for Mac and are coming to the iOS app in an upcoming update.

2Do has chosen not to host your task data because of the privacy and security responsibility that would entail. Instead, 2Do supports services you already trust — Dropbox, WebDAV, iCloud / CalDAV, Todoist, Toodledo, and Apple Reminders. The trade-off: sync is slightly slower than a dedicated solution would be, but your data stays with the provider you choose. See Which sync method should I use? for the full list.