Free GPS Tracker by GEOLINK allows to track mobile phones in the browser. Simply open free account on https://geolink.io, install this app and start tracking.
1. Install the app, click "Start Tracking"
2. Open free account on https://geolink.io
3. Your phone's ID will be displayed in the app, just activate it on geolink.io by following this guide: https://geolink.io/guide.php