wp-commission

This plugin is not the same as Amazon Native Ads, as the other reviewer mistakenly believes. This plugin scans your posts (including all existing posts and custom post types) to see what Amazon items you are linking to. It then automatically adds your Amazon Affiliate link to the amazon urls in your content, which saves you a lot of time (especially if you have a group blog with different contributors -- they can't always be trusted to remember to add your tag or to not add their own tags instead). You also have an option to add a carousel ad of Amazon products based on the Amazon urls on your site. This keeps the ads relevant to what your users are reading on your site.

This plugin fixed our problem with many editors' Amazon links containing no Amazon Associates tag or someone else's Amazon Associates tag. Better, it unpacks and rewrites amzn.to shortlinks and adds our Associates tag to those too, so that we get paid. Props.

They charge you $59-$479 per year to use this. Amazon has something called Native Shopping Ads that is 100% free and looks like the exact same thing as this plugin or Skimlinks has great tools as well. They also are spreading this via unsolicited spam emails so that is why I'm giving this plugin a 1 star. Stop spamming, it's a horrible first impression when you send the same email multiple times to someone who didn't ask for it.

This is working very well for us. Consistent, good support, looks like very modern code. Has certainly made it easier for us to earn commissions on links to Amazon products.