The
mobile app Mozilla Stumbler for
Android could be used to contribute signals of cellular networks and Wi-Fi access points at the device's GPS position. It was available in the
Google Play store and
F-Droid from November 2014 to February 2021 after which it was officially retired. It was noted that contributions from Firefox for Android users "completely overwhelm[ed] the contributions made by the dedicated Stumbler app." Other apps, such as
Tower Collector, were also available for the same purpose, although they were limited to collecting information related to cellular networks, except for
NeoStumbler an Android application capable of collecting locations of cell towers, Wi-Fi access points and Bluetooth beacons. Firefox for Android had the option to contribute to the service in a similar manner to Stumbler up until Firefox version 68, after which Mozilla performed a major rewrite of the browser, and the option to contribute to MLS was not re-added. Mozilla does not collect the
SSID name (e.g. "Simpson-family-wifi") from WiFi networks, but does collect the
BSSID (which is often the
MAC address of the WiFi device). When the service is used to request the geolocation of a device by sending it information about nearby radio transmitters, it not only responds with a location estimate, but also uses the data to update its own database. For example, if a device requests its location by sending the service information about 7 nearby Wi-Fi networks, but MLS only knows about 5 of them, the information about the 2 previously undiscovered Wi-Fi networks will be added as a data point at the device's estimated location. These requests are also used to verify that the 5 reported Wi-Fi networks still exist, and that their characteristics, such as their location, orientation, or other factors that might alter the signal, are unchanged. If they are changed, for example, by someone moving their
Wi-Fi router to another room, then the device gets the
Blocked status, which means that it isn't taken into account for location queries for 48 hours. If the device then remains stable at its new position, it is considered usable again. If it were to keep moving, it will be considered a moving emitter, and will not be taken into account for location queries. This is used to filter out, for example, Wi-Fi access points on buses and trains, and
mobile hotspots created by phones and laptops. Mozilla publishes aggregated data set of cell locations (MLS Cell Network Export Data) under a
public domain license (
CC-0). Unlike the cell database, the raw WiFi database is not made public because the underlying data contains
personally identifiable information from both the users uploading data and from the owners of Wi-Fi devices. == Usage ==