Hi,
I have experience for 15+ years in electronics/embedded development.
For your project I propose using an ESP8266-based solution (with an ESP-12 module) along with a current sensor like an ACS712 that is connected in series with the load (device you want to monitor) that you want to know if it's switched on or off. Depending on which device you want to connect, other sensor might be needed instead of this. The communication with the mobile device is through wifi.
This bid is for a device assembled in a prototype board only, no custom PCB layout, although this can be discussed and arranged later.
Along with the device itself, a prototype app is included that will show if the device is on or off, updating the information in realtime. This prototype app will be developed in a simple android app sketching environment like app inventor or similar. Other options may be discussed.
If the device itself is needed (physically), shipping and handling costs are supported by you and local pickup to my address must be arranged at the time.
Before any payment is made, I'll provide a videos demoing the final implemented project or if it's needed, intermediate project status.
If you are interested in my bid, please let me know some more details about your project and I'll be able to answer you back telling if I'm up to the task or not. Feel free to contact me.
Regards,
Carlos.