Esptouch is one way to tell the connected Router's SSID, Password and etc. to make IOT devices to connect to the same Router. Esptouch is developed and maintained by Espressif Corp.
The system can only be connected successfully after the external device is started.
This build is from the official GitHub repository.
For more information please see Esptouch documentation: https://www.espressif.com/sites/default/files/documentation/esp-touch_user_guide_en.pdf
Link to GitHub repository: https://github.com/EspressifApp/EsptouchForAndroid