The only credentials saved are those created for the KPIwatchdog account itself.
Depending on the type of connector, you grant the permission in your data source to send the select reporting data to KPIwatchdog via the existing data source API (Google Analytics, Facebook, etc.). This permission can be revoked anytime.
If the data source does not have an API in place, we provide the tools to create it on your side (e.g. DB Connector for websites with MySQL database). Such tools create read-only API and are authenticated via the special API key. You are never asked to submit your database credentials or password directly on the KPIwatchdog.com website.