Quality management and improvement for geothermal energy projects using the platform-based tool development technology − ZWERG

•An approach for modular platform based downhole tool development for harsh conditions is presented.•Advantages in terms of development time, quality and reusability of results are demonstrated.•Engineering solutions for pressure and corrosion resistant housing, heat management and data transfer are provided.•The platform is usable as basis for a wide range of downhole tools for different applications.