doc2git
TL;DR: When you process a doc using doc2git, the only communication is between your browser and Google. No content or information relating to that doc is stored or shared. The resulting zip file only exists in your browser until you download it, and it isn't uploaded anywhere.
Google user data
When you authenticate with Google, doc2git displays your name, email address and profile picture to allow you to identify which account you've signed in with. This data is not stored or shared.
When you enter a Google Doc URL, doc2git requests read-only access to your Google Drive.
This access isn't persisted. I.e. The access token isn't stored anywhere except your browser, or transmitted elsewhere.
doc2git uses this only to access the Google Doc you requested.
doc2git uses the Google Drive API to fetch the list of revisions to this Doc, and creates a plain text export of each revision. This export is committed to the Git repo (in your browser) with the corresponding author (name and email address) and time of revision.
The Git repo is made available to you as a download, but isn't stored anywhere or shared.
Once you close the browser tab running doc2git, all access and Google user data is gone.
Tracking / analytics
In order to protect your privacy, doc2git does not use any web analytics.