Tachograph File Viewer, developed by Tachosys, is a free Android application that allows you to view digital tachograph files on your Android device. The app is primarily designed for commercial drivers and fleet managers who need to view tachograph data on-the-go. Tachograph File Viewer supports various file formats, including Driver Card files (Summary, Activity, Vehicles Used, Places, Specific Conditions), Vehicle Unit files (Summary, Activity, Card Insert/Withdrawal, Faults, Events), and Workshop Card files (Summary). Moreover, the app is Smart Tachograph (1C) compatible. Tachograph File Viewer is a useful tool that helps users view and analyze tachograph data anytime, anywhere.

However, it's worth noting that the Android app is a basic version of the fuller Tachograph File Viewer available for Windows PC. The Android app lacks some of the features available in the PC version, but it still provides enough functionality to view tachograph files. Overall, Tachograph File Viewer is a helpful app for commercial drivers and fleet managers who need to access tachograph data on their Android devices.