EMF Mapper is an independent citizen science initiative that makes electromagnetic field (EMF) levels more visible through crowdsourced measurements. As mobile networks, Wi-Fi, smartphones and other connected devices have become widespread, the platform aims to give researchers, residents and policy-makers transparent, street-level information about radiation levels.

Its interactive map lets visitors explore measurements by location, compare results across cities and regions, and see how readings vary between streets or in relation to nearby antennas. Users can also browse measurements by country, city, municipality or other area, with options to examine changes over time. The data currently comes predominantly from the Netherlands.

EMF Mapper encourages volunteers to contribute their own readings using a Safe and Sound Pro II meter. Contributors are asked to follow a standardised protocol developed by Prof. Dr. Magda Havas and use the same type of calibrated meter, helping make measurements more comparable. By collecting and presenting these observations, EMF Mapper builds a growing resource for understanding electromagnetic radiation and supports informed discussion about local exposure levels.