I am not the person you asked, but I take screenshots for archival purposes not-infrequently (as seen here: https://news.ycombinator.com/item?id=10845275 https:

I am not the person you asked, but I take screenshots for archival purposes not-infrequently (as seen here: https://news.ycombinator.com/item?id=10845275 https://news.ycombinator.com/item?id=10845275). The tool that I use is Phantomjs with a script called 'rasterize.js`. The big plus for me was the ability to render arbitrary dpi images of web pages.