I downloaded Postman for Linux (from https://www.getpostman.com/apps), unpacked .tar.gz file into ~/bin/postman and then tried to execute ~/bin/postman/Postma
~/bin/postman
~/bin/postman/Postma
Was having an issue getting the "Run in Postman" links to work with the browsers until I added this to the .desktop file
MimeType=application/postman;x-scheme-handler/postman;