Yes. They are.
We save your words every time you pause in your writing so you don’t need to worry – they are very safe indeed. We back them up in two additional separate places (on different continents!) too, to be sure.
You can also sync with Google Drive or Dropbox for automated daily/monthly backups of your novel. You can do this from the Export tab in your account settings (top right icon).
You can also export your words from the Export tab as .docx, .pdf or .odt at any time you like if you’d like to make your own backups (we don’t think these are necessary).