I used to use the old Scrapbook extension for Firefox which became defunct with Firefox 57.
WebScrapBook is a perfect replacement for newer browsers.
(Web)ScrapBook is amongst the most useful browser extension out there. It allows you to save and, annotate and markup (highlight) webpages that you come across whilst browsing the internet. It is an excellent tool for research.
And on top its free. This extension deserves to be more popular.
The unique selling point of (Web)ScrapBook is, that it completely resides within your browser. It's not connected to any service that siphons off your personal and private data.