Last Adjustments in the Amazon A9 Algorithm

Amazon is continually adjusting its A9 algorithm. Therefore, it is necessary to be very attentive and take it into account and thus optimize in the correct way in order to obtain the desired results.

The difference between Byte and Character

Before mentioning the latest modifications in the A9 algorithm, it is necessary to indicate the difference between Byte and Character. This refers, in computer and telecommunications terminology, to the unit that corresponds to each symbol, like those in an alphabet. An example of a character is a letter, number, or punctuation mark.

It is very important to differentiate them to improve the indexing of products by Amazon. Typical characters (for example, those from A to Z) occupy 1 byte each while those that are special (letters with accents, umlauts, &, %…) count as 2 bytes. It seems silly but it is not when optimizing because if you do not take it into account, some keyword may not be indexed properly.

We will briefly and easily detail the latest changes in the algorithm. The changes apply whether you are selling in Vendor mode or if you are doing it in Seller mode and affect two aspects: Keywords and Product Listing.

Changes regarding the use of Keywords (keywords)

Until this new change, it was important to include Keywords in four sections of the product listing: in the title, in the “backend keywords”, in the bullet points or product characteristics and in the description (in this last section they were not always indexed). By working these sections correctly we could achieve a positive effect on the ranking of our products, for example, by including a highly searched keyword in the title.

Well, from now on the placement of the keyword no longer plays any role in the organic ranking. Now Amazon relies more strongly on the performance of the keyword of a specific product (its number of clicks, its conversion rate, its sales …). What is Amazon looking for with this change? Well, manufacturers focus on the content of their product sheets and that this content is focused on the conversion of said product.  

Changes in the most relevant sections of the product listing for the algorithm.

There are 5 relevant sections for the new algorithm that we have to take into account when optimizing our products.


The title is indexed in its entirety and although there is some change to mention, what is still mandatory is the specific taxonomy of vendor and seller.

Amazon can remove products with very long titles so that no matter how hard you try, you won’t find them. Therefore, they cannot exceed 200 characters including spaces.

Backend Keywords.

The backend keywords or also called search words are those that are “behind” the product sheet – those that are not seen – and are essential for the organic positioning of the product. Now, if they exceed 249 bytes (including both spaces and accents or punctuation marks) none of them will be indexed. When this feature is fully implemented, an alert will appear indicating that you cannot save them and until you meet the requirement it will not let you save and activate the changes.

Here the question or doubt comes from those products that currently exceed this figure. No problem, they will remain indexed for now. We remind you that it was a maximum of 250 bytes without including spaces. But let’s take it into account when optimizing them – from top amazon ungated categories services we recommend to all our clients a minimum monthly optimization and, thus, we can check if they disappear in a short period of time if the algorithm makes our product disappear.

Bullet Points or Product Features.

Only the first 1000 bytes – including spaces – of the 5 bullets in total are indexed for search. From 1001 they will not be considered. This does not mean that you cannot continue using the 500 characters per bullet, but if you want to avoid a negative effect on your conversion rate, you should shorten the text of each bullet. Taking into account that we have 5 bullets, from Amazing we recommend trying to use a maximum of 200 bytes in each of them to achieve maximum indexing.


The product category is still the deciding factor when indexing the product description. This is still 2000 characters including spaces. It is the perfect section to include longtail keywords in the context of Amazon SEO. Even so, this section has many indexing limitations, so we recommend that it continue to be the space to make our client fall in love, with persuasive content to help the final conversion.

A + Content and Rich Content

Neither A + Content for Vendors nor Rich Content for Sellers are indexed; In other words, the products will not appear due to the keywords included in this section, including the image tags. Here comes the question of whether to embark on creating it or not. Well, from Amazing we believe that if the keywords, if you include them in the backend there is no problem and this area is very visual and offers information that helps increase the conversion.

As we have said before, the changes will not take effect at once. Many of them, although they are already in force at, have not yet reached the European market but they will arrive and Amazon does not warn. Therefore, being aware and already taking these aspects into account when optimizing your catalog is essential to achieve success. We will be happy to help you with this matter and with any other aspect related to both your Vendor Central account and your Seller Central account. We are a consulting agency that only works on Amazon and we help increase our clients’ sales in the short term.