If you have found an interesting webpage with some sort of instructions that you want to use later, then you can either print it on a paper or save it for later. If you want to save a webpage in the Firefox web browser as an HTML file, then you can simple press Ctrl+S and choose to save that webpage as an HTML file. However, one drawback of this method is that it saved the HTML file along with a folder containing all the images, scripts and other associated files.
SingleFile extension for Firefox provides a simple solution and allows you to save any webpage in a single HTML file without needing any other files or folders. It saves all the images, scripts, CSS, fonts etc., inside the HTML file using base64 encoding so no external files are needed.
After the installation, you can simply click on the SingleFile icon in the Firefox toolbar and it will instantly save the current webpage in the default download folder. The page can also be saved using a hotkey Ctrl+Shift+Y. You can also right-click anywhere on a webpage and select SingleClick from the right-click menu to see many more options.
From the right-click menu, you can choose to save all the open tabs into HTML files, save selected tabs, save selected content, save unpinned tabs, make it auto-save a URL whenever opened and annotate a webpage before saving it.
When you choose to annotate a webpage before saving it, it will open a small editor where you will get tools like highlighter pens and sticky notes of many different colors that you can add anywhere on the webpage. You can also remove the various elements including text and images from the images before saving it.
You can get the SingleFile extension for Firefox from https://addons.mozilla.org/en-US/firefox/addon/single-file/.