I need to create a low level addon for FireFox, one that is accessible from a loaded page via JS code in the page, but is a Native extension to the browser. As I understand it, NPAPI is now no longer an option, and the PPAPI (Google) will be deprecated next year in 2021. The extension I'm tasked with cannot be provided by a browser extension like the ones in the mozilla store as it needs to provide additional API's that will be called from JavaScript code running in loaded pages, not under the control of myself, but all confirming to the same standard API calls. I've been trying a few proof of concepts using CEF (Embedded chromium) and have hit too many road blocks, so now I'm exploring a solution that will use Embedded Gecko and/or extensions to a running version of firefox. I've read a lot of the MDN content, but this either discusses HTML level topics (Which are of no use) or NPAPI (Which is now deprecated) Can you provide any pointers as to which technologies I should be exploring in order to accomplish my goal. For reference, the extensions I've been tasked with are to implement the OIPF HbbTV specifications into a standard browser to aid other developers in testing and developing standard HbbTV applications. Many thanks in advance. PS: Sorry about the title, I had to find a way to shorten it due to the text box length restriction :-)