You can create as many coordinated counters as you wish. You allow others to connect to one of your counters by telling them the counter name and its password.
If you're not connected to the network, updates you make to your counter are saved until you are again connected. Then your updates are applied as well as updates others may have made while you were off line.
Works over cellular as well as Wi-Fi connections.
Optional minus button may be added to any counter.
Negative counter values are supported.