Zundertrack - Zeiterfassung is a productivity application designed for iPhone users to efficiently manage projects and clients while seamlessly converting working hours into invoices. This free app offers an intuitive time tracking feature that allows users to start and stop their work hours with just a tap. It supports fixed-rate calculations, making it ideal for bookings that are not time-based.

The application also includes comprehensive customer and project management tools, enabling users to organize all relevant information in one place. Additional features include detailed descriptions for each time entry, easy export of service reports as PDFs, and flexible project management capabilities. Users can set individual hourly rates for each client or project, and mark specific entries as non-billable, ensuring precise tracking and invoicing regardless of the number of clients managed.