Wundere mich, weil ich nach Eingabe der URL nur Error: Server Error
The server encountered a temporary error and could not complete your request.
Please try again in 30 seconds, angezeigt bekomme. Jetzt lese ich in einer Antwort auf eine Bewertung, dass es nur mit URL von Elektroartikel funktioniert. In keinem Artikel über ReviewIndex wurde darauf hingewiesen.

Looking foward to other domains. Still, it is useful.
Maybe the following is easier than supporting new domains: Add the reviews from the supported domains into the according product sites of the unsupported domains.

Also, you should definitely include in the description its other limits, for example that it currently "works only for electronics products".

Great Idea. Saves a lot of time while reading reviews.

Such a good idea!

(Please add other Amazon domains (fr...).

I've tested the extension with this page: https://www.amazon.com/Ecology-Planted-Aquarium-Practical-Scientific-ebook/dp/B00DB94K5I
I've got: "Sorry! We were unable to summarize reviews for this product. This could happen if the product is a non-electronic product, or it has too few reviews or something went wrong with out backend servers. "