If that is your concern: "Save as..." works pretty well in modern browsers. I use Zotero for organizing the documents I want to keep and that works pretty well

If that is your concern: "Save as..." works pretty well in modern browsers. I use Zotero for organizing the documents I want to keep and that works pretty well too. I'm sure there are other options, offline (like Zotero) or cloud based. And there are always archive.org and archive.is...