a.co Links, Explained — and Shorter Amazon Links That Keep Your Tag

a.co is Amazon's own URL shortener. Tap Share on any product in the Amazon mobile app and Amazon hands you something like https://a.co/d/1a2b3c4 instead of the full /dp/ URL, which can easily run past 150 characters.

a.co is a legitimate Amazon-owned domain, not a phishing attempt — a reasonable question, since a bare two-letter domain looks suspicious and scammers do imitate it. A real a.co link always redirects to an amazon domain, and you can confirm this by long-pressing the link to preview it, or by opening it and checking that the address bar reads amazon.com (or your regional store) once it lands.

For sharing a product with a friend, a.co is perfectly good. For an affiliate, it has three problems.

They usually carry no affiliate tag. The app's Share button produces a consumer share link, not an affiliate link. Purchases made through it typically earn you nothing, and because the destination is hidden behind a redirect you cannot inspect the URL to check whether your tag survived.

They're locked to one marketplace. An a.co link created on amazon.com always resolves to amazon.com. Every reader in the UK, Germany, France, Canada, or Australia who clicks it lands on the US store, where they frequently hit higher prices, import duties, or a "we cannot ship this item to your address" notice — and leave without buying.

They give you no data. There is no click count, no country breakdown, and no way to change the destination later. If the product goes out of stock or Amazon changes the ASIN, every a.co link you have ever published is dead and you have no list of where they are.

Start by stripping the Amazon URL back to its essentials. A product URL copied from a browser is mostly tracking parameters — ref, pd_rd_*, psc, qid — none of which you need. Every Amazon product reduces to its ten-character ASIN:

That already cuts the link by roughly two thirds and — critically — the ?tag= parameter is now explicit and verifiable. You can see your tag, so you know you will be paid.

Then shorten it with a service you control. A Geo-Smart-Links Smart Link produces a gsl.li URL of about 20 characters — comparable to a.co in length, but yours: you can see the clicks, change the destination after publishing, and attach a different marketplace and tag for each visitor country.

Yes. Amazon's Associates Operating Agreement permits URL shorteners. What it requires is that you make the affiliate disclosure Amazon mandates, and that you do not misrepresent where a link goes. Shortening a correctly tagged link and disclosing it as an affiliate link is ordinary, accepted practice across the industry.

Two things to keep in mind. Amazon restricts affiliate links in email and certain offline contexts regardless of whether they are shortened, so check the current agreement before using them in a newsletter. And "cloaking" in the sense of deliberately concealing that a link leads to Amazon is not allowed — a short link that redirects transparently to a disclosed Amazon product is fine; one presented as something it is not is not.