As per Library Manager FAQ, I'm asking you to add my "Simple Web Serial" library to the Arduino library manager. Library URL: https://github.com/fmgrafikdesign/simplewebserial-arduino-library Release URL: https://github.com/fmgrafikdesign/simplewebserial-arduino-library/releases/tag/0.1.5 If there is any additional information you need, feel free to contact me. Thank you very much and have a nice day! Best Regards, Fabian