Day One

 Day One  is a subscription-based journaling app for iOS, macOS, and Android that offers import and export of your data, albeit with very restricted format options, and a sync feature with an API and IFTTT integration, so that it can be used as PASTA strategy.

How to export
Day One offers export in PDF, HTML, JSON, Plain Text, and CSV (limited to date and text, from iOS only).
 * http://help.dayoneapp.com/tips-and-tutorials/exporting-entries

Features
Day One stores extra data for each entry, like weather information, location, music and activity data.

Developer Features
The app offers a command line tool and a URL scheme that might make it more useful in an IndieWeb context.