The draw.io for Confluence/JIRA Cloud plugins are both static plugins. That means they are delivered as complete web applications to the users' browser and work without an additional server of ours being used.
Diagram data is only stored as attachments on your Confluence/JIRA Cloud instance and nowhere else. Save and load operations are direct between Atlassian's servers and the users' browser, they do not even transit through another server during these operations.
There are cases where data is sent to draw.io servers to perform operations where the client browser is not capable of the operation. In these cases the operation is performed, the result returned and both the input and output are not persisted in any way.
These functions are:
- Export to PDF
- Export to PNG for IE 11 and Safari
- Importing a .vsdx, .vssx or .gliffy file