ArduinoJson is available in Arduino’s Library Manager. You can automatically install it from there.
Something wrong with the Library Manager?
If ArduinoJson doesn’t appear in Library Manager, or if only old versions are listed, try to delete the local cache. For example, on Windows, you need to delete:
%LOCALAPPDATA%\Arduino15\library_index.json.tmp.gzYou don’t even need to close Arduino, just re-open the library manager.
You needed to download the zip package and extract it to:
<your Arduino Sketch folder>/libraries/ArduinoJson
Then restart the Arduino IDE.
ArduinoJson is a header-only library, so you just need to download the package and unzip it in a convenient location.
Then add the
include/ folder to your compiler’s or your IDE’s include directories.
In Arduino IDE, click