There has been a lot of confusion in the past month, and specifically the past week about changes that are taking place with Amazon's various API's. This post is intended to clarify what has happened and explain where things currently stand. A long time ago, Amazon created an API that Amazon Associates could use to advertise Amazon products on their own websites. It has gone through several names since its inception, including the Amazon Associates Web Services and the Amazon E-Commerce Services. As of about 2009, it has been named the Product Advertising API (shortened to PA-API) to clarify that it was intended for advertising Amazon products. The available functionality has changed slightly over time, but this API generally has allowed programmers to search for products in Amazon's catalog, and to find out prices of those products.
Signing up for the Product Advertising API has been a very trivial process requiring just an email address and password. In about 2008, they started requiring that you have an Amazon Associates account (Amazon's Affiliate Program) in order to access the API. However, the Associates account is very trivial to create and just requires an email address and password.
Since the API is so simple to gain access to, programmers have been using it for all kinds of things. Developers catering to Amazon's growing 3rd party seller market began using the API to create automated repricing programs and various other tools that assisted legitimate sellers on Amazon.
Unfortunately, it was difficult for Amazon to identify legitimate users of the service. Since the data is pretty useful, many programmers would create tools that had nothing to do with driving traffic to the Amazon.com websites, and the Product Advertising became a very general-purpose product catalog with many types of users.
Starting in about August 2009, Amazon started to tighten down access. At that time, they started requiring a cryptographic signature with each request. This effectively prevented access to the API from credentials that were freely published and out "in the wild". This required any users of the API to have a "Secret Key", and any programs using the API needed to be modified to work with this new requirement.
In 2010, Amazon started to restrict usage on the API. Their Efficiency guidelines limited users by default to only 2,000 requests per hour. This seems to be the point where Amazon started to really gain control over access to the API. Amazon Associates who drove sales to the Amazon.com website were supposed to have this limit increased, based on the number of sales that they helped to bring to the site (although there is some debate if that ever worked). People who needed increased limits seem to have been somewhat successful at gaining exceptions to this 2,000 requests/hour limit. Presumably, some sellers became exempt, as well as tools that catered to third party sellers.
More recently, in 2011, Amazon announced that many of the useful data points in the Product Advertising API would be removed. This became the 2011-08-01 version of the API that only provides the lowest price offer for each product. Many of the details including the Seller's Comments and quantities were also removed. This version of the API became useless for sellers who needed a wider range of data to make important pricing and sourcing decisions.
Although never really publicly announced, we can now tell from recent forum posts, that Amazon separated the Product Advertising API into two distinct versions. The Associates Version of the API became the 2011-08-01 branch that included the very limited data. They also had a separate Sellers Version of the API that they allowed sellers to access if the seller knew how to properly ask for it. The seller's version of the API remained at version 2010-11-01 and still had access to all of the pricing data that sellers were used to having available.
Several weeks after the 2011-08-01 version was announced (Although the version is dated from August 2011, it wasn't actually announced until February 2012), and observant sellers were getting really worried about what the changes meant for their business, Amazon announced the new MWS Products API. This new API finally offered a legitimate way for sellers to access pricing information necessary for them to make important business decisions.
Unfortunately, the new MWS Products API presents data in somewhat of a different format and doesn't have as much detail as the sellers version of the Product Advertising API provides. Notable omissions are any seller identifying information (no seller ID, seller names, or even identifying Amazon.com as a seller). Quantities are obviously absent, as are the condition-notes that allow sellers to describe their specific offer in detail. (More details about the changes to the data can be found in this blog post)
That brings us to where we are today. The Sellers Version of the Product Advertising API is scheduled to be shut down in less than a month on August 31st, 2012. Sellers are to migrate to the new MWS Products API by that date. Amazon has most recently been severely limiting access to the Seller Version of PA-API, responding with Blacklist errors so that sellers will pay attention to this upcoming change.
I don't know of any products that are currently using the new MWS Product API Data. That seems a little worrisome with only 4 weeks remaining until PA-API is shut down. There are some technical limitations to the new API as well that make it less convenient for programmers to use. I've created BetterMWS as a way to bridge that gap. It provides a simpler way for programmers to access the wide range of data that is available through MWS without having to jump through all of the hoops.