XSD Viewer Cloud is hosted on Heroku, which runs on Amazon Web Services (AWS) in the United States.
Heroku has published a security statement which you can find here: Heroku security statement.
XSD Viewer processes your appointed XSD attachments in order to display it within Confluence. This data is stored within Confluence.
Your XSD attachments is transferred but not stored, cached or otherwise retained outside of Confluence.
We make sure that our products are as secure as possible by attending to the following things:
TLS 1.2+ encrypted connections to and from our service.
HSTS to prevent downgrade attacks and cookie hijacking.