Amazon to eBay Firefox Automatic Link Generator Add-on/Extension

The following extension adds a link to the eBay search page on the Amazon product page for the product being viewed for comparison. Clicking on the link opens a new tab with eBay search results for the Amazon product. 

Create a folder named amazon_ebay and add the following manifest.json and amazon_ebay.js files to this folder.

Go to about:debugging in Firefox and click Load Temporary Add-on and load the manifest.json file.

Then visit a product page on Amazon (amazon.com) and there will be a link 'eBay', just below the product title, pointing to the corresponding search results in eBay (ebay.com). By making appropriate changes to the manifest.json and amazon_ebay.js files you can get this extension to work on Amazon/eBay of different countries.