Greasy Fork - A site for user scripts.
HTTrack - HTTrack is a free (GPL, libre/free software) and easy-to-use offline browser utility.
Violentmonkey - Violentmonkey is a userscript manager to support running userscripts in web pages.
Web ScrapBook - A browser extension that captures the web page faithfully with highly customizable configurations.
Userscripts - An open-source userscript editor for Safari.
SingleFile - Save a complete page into a single HTML file