SwitchIoT is a free Android tool developed by Bluino Electronics that guides you to make a DIY Sonoff smart switch based on the ESP8266/ESP8285 chip. With this app, you can directly upload firmware to ESP8266 and set it up without the need for a computer or laptop. Making an IoT device is as easy as uploading firmware without the need for registration, login, or server configurations.

This app comes with features such as remote control, scheduling, timer, loop timer, sharing, and firmware uploading. The app is compatible with ESP-01, Wemos, NodeMCU, Bluino IoT Kit, Sonoff Basic R1/R2/R3/mini, and ESP8266/ESP8285 modules.

If you're interested in making a DIY Sonoff smart switch, follow the tutorial provided in the app. It's a straightforward guide that will help you create your smart switch in no time.