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

2Do does not host your task data, because of the privacy and security responsibility that would carry. The native apps sync through services you already have: your own iCloud account, Dropbox, iCloud CalDAV and other CalDAV servers, Todoist, Toodledo, and Apple Reminders. WebDAV sync is coming soon.

The iCloud method uses your own Apple-hosted storage, private to your account. On iPhone, iPad, and Mac, it uses the iCloud account already signed in on your device. On Android, you sign in with your Apple Account from 2Do. Native iCloud sync connects directly to Apple, with no separate 2Do sync account or copy of your task database stored with us. See iCloud sync on Android.

The trade-off is that sync goes through someone else's service rather than one tuned end to end for 2Do. In exchange, your data stays with the provider you chose. See Which sync method should I use? for the full list.

2Do for Web uses your iCloud account through CloudKit and keeps a local working copy in the browser. We do not host your task database. Attachment and large-note uploads pass through a transfer relay on their way to Apple, as explained in the Web Privacy Policy.