The Once-Only Technical System (OOTS) aims to let EU public authorities securely exchange official documents and data at the request of citizens and businesses as part of cross-border administrative procedures, e.g. when registering an address or vehicle when moving abroad. It eliminates the complicated manual search, mapping, and fetching of data between Member States authorities, improving efficiency, making people's lives easier, and reducing mobility costs within the EU.

The Once-Only Technical System creates an interoperability layer between EU Member States. It uses the eID and eDelivery building blocks for authentication and data exchange. It uses Once-Only Common Services (the Evidence Broker (EB), the Data Service Directory (DSD), and Semantic Repository (SR)) for the exchange of evidences between the Data Services and Online Procedure portals connected by the Once-Only Technical System.

The Commission also provides the Once-Only Hub, compiling all relevant information regarding the Once-Only project, a service desk and organises various events.

This monitoring dashboard records statistics related to all these elements of the Once-Only Technical System.