OpenCellID - OpenCelliD is the largest Open Database of Cell Towers & their locations. You can geolocate IoT & Mobile devices without GPS, explore Mobile Operator coverage and more!
Sortd - Rated the #1 App for Gmail
wigle.net - WiGLE (Wireless Geographic Logging Engine)
KanbanMail - A Kanban board for your emails.
Proxidize - Proxidize is the world's premier self-hosted 4G mobile proxy solution! With Proxidize at your fingertips, building a 4G mobile proxy network of any size is a breeze - absolutely no technical expertise required, we got you covered!
Trello - Infinitely flexible. Incredibly easy to use. Great mobile apps. It's free. Trello keeps track of everything, from the big picture to the minute details.