Well that's still will be something using NPAPI https://en.wikipedia.org/wiki/NPAPI https://en.wikipedia.org/wiki/NPAPI which means old. Back in the days browse

Well that's still will be something using NPAPI https://en.wikipedia.org/wiki/NPAPI https://en.wikipedia.org/wiki/NPAPI which means old. Back in the days browsers didn't have build in flash, java, divx player etc. so they was done by extensions aka plugins back in the days, so no, toolbars was not the only extensions in 90s. I guess there have to be some kind of extension that went from Netscape to Firefox etc. In there late 90s there was extension pack giving a lot of functionality to IE called MyIE (today known as Maxthon). You have to define what "modern extension" means to you because I have a feeling that you are looking just for oldest Firefox/Chrome extension.