Development Certificates

This step is only required if you want to create Office.js add-ins: Create TLS certificates for localhost by downloading mkcert (pick the correct file according to your platform), rename the file to mkcert, then run the following commands from a Terminal/Command Prompt (make sure you’re in the same directory as mkcert):

./mkcert -install
./mkcert localhost 127.0.0.1 ::1

This will generate two files localhost+2.pem and localhost+2-key.pem: move them to the certs directory.