seller
- What changed
- Amazon's product search and ranking system, named after A9.com
- When
- Updated October 2026
- Who it affects
- All sellers and vendors who rely on Amazon search
- What to do
- Get indexed for the right terms, then win on conversion
Key takeaways
- A9 is named after Amazon's former search subsidiary; sellers use it to mean Amazon search ranking.
- Relevance gets a listing indexed; conversion, sales and stock decide its position.
- In 2026, titles are capped at 75 characters and Item Highlights adds 125 searchable characters.
From A9.com to Amazon Search
Amazon creates A9.com for search tech
A9.com site taken down, team becomes Amazon Search
Rufus renamed Alexa for Shopping
Amazon announces 75-character titles
Title limit enforcement begins
Where the A9 name came from
A9.com was an Amazon subsidiary focused on search and advertising technology, based in Palo Alto. The name is a numeronym for algorithms. Its technology powered product search on Amazon's sites and features such as Search Inside the Book. According to Wikipedia, Amazon took the A9.com site down after 2019 and the team became Amazon Search.
Sellers kept the name. When people say A9 today they mean Amazon's product ranking in general, and many now say A10 for the newer version. Our Amazon A10 algorithm guide explains why that label is unofficial too.
How the A9 algorithm works: indexing then ranking
Think of Amazon search as two jobs. The first is indexing and retrieval: Amazon reads your listing fields and decides which searches you are relevant for. The second is ranking: among relevant products, Amazon orders results by signals that predict a purchase and a good customer experience.
- Indexing reads: title, Item Highlights, bullets, description, backend search terms, attributes and category
- Ranking weighs: sales history, conversion, click-through, price, reviews, stock and delivery speed
- Results are personalised by location, Prime eligibility and shopper behaviour
Relevance factors you control
Relevance starts with words. Since July 27, 2026, Amazon limits titles to 75 characters, including spaces, in every category except media, and offers a separate searchable Item Highlights field of up to 125 characters. Put the primary keyword in the title, then use Item Highlights, bullets and backend search terms for synonyms and secondary phrases.
Backend search terms are hidden from shoppers but indexed. Third-party guides put the US limit at 249 bytes; keep it short, skip commas, and do not repeat words already in the title. See our Amazon backend keywords guide.
Attributes matter too. Size, colour, material and other structured fields feed filters, and a product missing from a filter is invisible to shoppers who use it.
- Primary keyword in the title
- Secondary keywords in Item Highlights and bullets
- Synonyms and spelling variants in backend terms
- Every relevant attribute filled in
- Correct category and browse node
Performance factors that decide rank
Once you are relevant, performance decides position. Amazon does not publish weights, but sellers consistently point to conversion rate and sales history as the strongest signals. A listing that wins clicks and turns them into orders tells Amazon that shoppers like it for that search.
- Sales velocity for the specific keyword
- Conversion rate from search
- Click-through rate from the results page
- Price competitiveness and Buy Box
- Ratings and reviews
- Stock levels and fulfilment speed
Does A9 still exist in 2026?
The A9 brand does not, but the system it started does, retuned many times. Two 2026 changes matter. Titles got shorter, which moves keyword work into Item Highlights and backend fields. And AI shopping grew: Amazon says Rufus was renamed Alexa for Shopping on May 13, 2026. AI answers draw on listing text and reviews, so factual, specific copy now helps in two places. Read our Rufus optimisation guide for more.
- 1Research
Find real shopper keywords
- 2Map
Assign each to a field
- 3Write
Title, highlights, bullets
- 4Convert
Images, A+ and reviews
- 5Sustain
Ads and in-stock inventory
How to optimise for the Amazon A9 algorithm, step by step
Follow this order so each improvement builds on the last.
- Find the keywords shoppers use with Brand Analytics and search term reports
- Map each keyword to a field: title, Item Highlights, bullets or backend
- Write a title of 75 characters or fewer that leads with what the product is
- Fill every attribute and confirm the category
- Improve images and A+ Content to raise conversion
- Run Sponsored Products on core terms to build sales history
- Keep inventory in stock and review search terms monthly
Mistakes that hurt A9 rankings
Common problems include stuffing the title with repeated words, which also breaks Amazon's title rules, leaving attributes blank, putting competitor brand names in backend terms, and running out of stock during peak weeks. Each one either removes you from the index for a search or lowers the signals that decide your position. A monthly listing check that covers titles, attributes, backend terms and stock cover catches most of these before they cost rank.
Where PPC Spider helps
PPC Spider's Amazon SEO services handle keyword mapping, titles under the 75-character limit, Item Highlights, backend terms and attributes, while SpiderOS tracks search terms and stock alongside ads. Start with a free Amazon audit, and see our guide to Amazon keyword research to build your keyword map.
Sources
- Wikipedia: A9.com (en.wikipedia.org/wiki/A9.com)
- PPC Land: Amazon cuts product title limit to 75 characters on July 27 (ppc.land/amazon-cuts-product-title-limit-to-75-characters-on-july-27/)
- About Amazon: Amazon Rufus (aboutamazon.com/news/retail/amazon-rufus)
- SellerSprite: Amazon backend search terms, the 2026 complete checklist (sellersprite.com/en/blog/Amazon-Backend-Search-Terms-The-2026-Complete-Checklist)
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