ID and Password
We don't store your Dropbox and Google Drive passwords. (We cannot access this information.)
We store your OAuth token for Dropbox and Google Drive in our server.
We store a cookie in your browser.
We store your e-mail address for Dropbox and Google Drive in our server. This is for you to identify what account you use on Writebox.
File Contents
We don't store your file contents in our server, but save in your local cache.
We don't read your file contents, we just convert file encoding to show characters correctly.
We store the filepath of the thing you last opened in Writebox in our server. This is for syncing the last edit of the file across devices.
Logging
We collect analytics data through Google Analytics when you using Writebox. This is for the purpose of service improvement.
We don't track individual users.
Dev is a Japanese fellow on Twitter @kazuhiroshibuya, I'm sure he'll appreciate new users and any kudos. It's really well-designed and like others who commented here, I'm very glad for the prominent privacy disclosures on the homepage.
Helps you to concentrate on writing
We don't store your file contents in our server, but save on your local for cash.
Need to change cash to cache maybe?... or maybe not. Nice biz model. :)
Unfortunately, it's got a serious bug, fatal for my usage, which the developer promised to fix over a month ago but which has not been fixed yet. If you edit and save a web page (i.e. an .html file) on Google Drive, Chrome OS no longer recognizes the file as a web page to be viewed in the browser, but only as a text file, to be viewed as text or edited.
Eventually, this might be a good app. In the meantime, if you need a text editor for a chromebook, put it in developer mode, install Ubuntu 'cli-extras' with the Crouton script, and 'sudo apt-get install nano'. (Vim is also automatically installed by Crouton.)
I would like to request a feature to sync with Evernote.