What is the tool? https://super-productivity.com/

Just a quick note for others who might be looking for this as well. Took me some fiddling to get this to sync with Fastmail’s webdav.

  1. First setup an app account for DAV in Fastmail - https://www.fastmail.help/hc/en-us/articles/360058752854-App-passwords
  2. Probably enable Compression and E2EE
  3. Sync provider is WebDAV (duh)
  4. Base url is https://webdav.fastmail.com/
  5. Username is your normal login [email protected]
  6. Password is the app password you setup in step one.
  7. Sync folder path is JoeBlow.fastmail.com/files/super-productivity Repalce the @ in your login with a period.

If you are getting sync errors or issues make sure that both your mobile and desktop clients are on the latest version. I had the desktop version via snap package and it was on 10.xx where was the mobile was on the latest 11.0.0. I installed the deb and now they are working great!