The 4chan Archive Image Viewer is a Chrome add-on that allows users to quickly view images from a page without the need to open them in a new tab. This add-on provides an in-page overlay, making it easy to view thread images without the hassle of switching tabs.

One limitation of the add-on is that it cannot be used with the traditional /b/ archive due to cloudfront policy. However, any expired 4chan thread from the default archive site, archive.moe, will be rerouted to thebarchive.com, which allows for grabbing images from the source and displaying them in-page.

Overall, the 4chan Archive Image Viewer is a useful tool for 4chan users who frequently browse archived threads and want a convenient way to view images without opening multiple tabs.