https://pinocc.io/

Mesh networked, web-connected.

Field Scouts talk to each other using a mesh network (called a Troop), using an extremely low-power radio. This makes them 14 times more efficient than standard WiFi devices. Slap a WiFi backpack on a Scout to make it the Lead Scout, and connect your entire Troop to the web!

Sending messages between Scouts (or out to the web) is super straightforward, and it all just works.