Product Details is a public JSON API which contains release information for Firefox (desktop and mobile) and Thunderbird. The data is managed by the Release Management team through Ship-it and exported available at this domain:
htttps://product-details.mozilla.org/
Each branch corresponds to an environment:
masterbranch -> development environment -> used locally for developmentstagingbranch -> staging environment -> https://product-details.staging.mozilla-releng.nettestingbranch -> testing environment -> https://product-details.testing.mozilla-releng.netproductionbranch -> production environment ->- https://product-details.mozilla.org
More about product details you can read on the wiki: https://wiki.mozilla.org/Release_Management/Product_details