OpenWifiStatistics is an Android application used to scan wifi networks, gather statistics about them like BSSID, signal level, frequency, security settings and location and upload the data to a server for analysis. It is open source and you can view the code for the android app here https://github.com/uberspot/OpenWifiStatistics and the code for the web interface here https://github.com/uberspot/OpenWifiStatistics-web
This projects isn't actively developed for a long time now.
Note: No personal data (name, device info etc) are transmitted. There is no correlation between the wifi statistics and the devices that recorded them.