Install ESP8266 core for Arduino IDE

1. Install latest Arduino IDE.

2. Download and install Blynk library (follow instructions of the latest release package).

Then, open the Arduino IDE, then select in the menu: File -> Preferences (Arduino -> Preferences for Mac).

Click on Additional Boards Manager URLs button and add this link:

http://arduino.esp8266.com/stable/package_esp8266com_index.json

In the Arduino IDE open: Tools -> Board -> Boards Manager . Search for esp8266 , and install it:

Troubleshooting

In case you see Error downloading http://downloads.arduino.cc/packages/package_index.json like this:

You need to find folder Arduino15 or .Arduino15 and remove all files inside with package word in name.