How to get the latest stable version of Firefox?
I pulled this from the Firefox Chef cookbook (in particular this .rb file). This an example of the request they use to get the latest version based on OS and language. 

https://download.mozilla.org/?product=firefox-latest#&amp;os=win#&amp;lang=#en-US


It adheres to the following format:

https://download.mozilla.org/?product=firefox-{VERSION_NUMBER}#&amp;os={OS_ABBREVIATION}#&amp;lang=#{LANGUAGE_ABBREVIATION}


I searched around for official api documentation, but couldn't find anything. If I do, I will post a link to it in this answer.