Activ is a free application developed by the Swiss Federal Customs and Border Security Office (UDSC), designed to facilitate the passage through Swiss customs. This app allows for the automatic activation of customs declarations based on the international transit documents T1/T2. It is available for download on mobile devices and can be used exclusively when the vehicle is stationary, requiring an active internet connection and mobile telephony (including roaming). Users must carry the transit document in paper form, which serves as an emergency solution in case of malfunctions of the NCTS system.