We’ve added an options page to our chrome browser extension to compare Amazon products.
The first option (enabled by default) will add a button below the price on the Amazon website. The button will work exactly as the right-click with the button (add to current comparison).
You can use the button for each product variation. See the example below for the two sizes of the Galaxy S9+, and get a comparison of Galaxy S9 VS Galaxy S9+ or any other variation.