Install latest Arduino IDE.
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.