How eBay's Cassini Search Engine Ranks Listings

Cassini is eBay's search engine, and Best Match is the name of its default ordering. When a buyer searches, it first works out which listings match the search, using the title, category, item specifics and product details. It then ranks them using factors eBay lists itself: how closely the listing matches the search, how popular the item is, its price, the quality and completeness of the listing, its returns and handling terms, and the seller's track record. The results are then adjusted for each buyer, including their location and browsing history.

This article explains how that mechanism works. It does not repeat the practical fixes: how to optimise eBay listings is the how-to, and the individual parts of a listing each have their own guide, linked below.

What Cassini is, and what Best Match means

Cassini is the name of the search engine eBay rolled out in the early 2010s to replace its older system. eBay's own help pages rarely use the name. They talk about Best Match, the default sort order buyers see unless they choose another.

Two consequences follow. First, when a buyer sorts by lowest price, ending soonest or newly listed, the sort decides the order and most of the Best Match ranking is bypassed. Second, everything below is about the default view, which is where most browsing starts.

Two jobs: matching, then ranking

Like most search engines, eBay's does two separate things, and confusing them is behind a lot of wasted optimisation.

Matching decides whether your listing is in the results at all. It depends on whether the words and details in your listing correspond to the search and to any filters the buyer has applied. If a buyer filters by size, colour or brand and your listing has that item specific blank, it drops out of the filtered view entirely. Matching is close to yes or no.

Ranking decides the order among the listings that matched. That is where the Best Match factors apply.

The distinction tells you what kind of problem you have:

Seller Hub's traffic reporting shows impressions, click-through and sales conversion for your listings, which is enough to tell these apart.

What eBay says Best Match weighs

eBay's help page on optimising your listings for Best Match lists the factors at the time of writing (October 2026). Here they are, with what each most plausibly covers in practice. The right-hand column is my interpretation, not eBay's wording.

eBay's Seller Centre page on getting found in search adds that Top Rated Seller status brings improved visibility in search across all your listings, and recommends free or competitively priced postage, fast dispatch, a generous returns policy and product identifiers.

eBay does not publish the weights, and they almost certainly vary by category and change over time. Anyone presenting a precise ranking formula is guessing.

Listing signals and seller signals

The factors split into two groups that behave differently.

Listing signals belong to one listing: its match to the search, its price, its completeness, its photos, its terms. You can change them today, and they are why one listing outperforms another from the same seller. eBay item specifics and eBay product titles cover the two that decide matching.

Seller signals apply to every listing you have. A run of late dispatches or unresolved cases affects your whole catalogue, not just the order that went wrong, and these signals move slowly because they are measured over evaluation periods. eBay seller performance standards explains how they are calculated.

This is why a well-written listing from a struggling account can sit below an average listing from a healthy one.

Popularity creates a feedback loop

'How popular the item is' means a listing that sells tends to be shown more, which gives it more chances to sell. A new listing has no history to draw on, so it competes on its match to the search, its price and its terms until it builds some.

Two consequences follow, both inferences from how eBay describes Best Match rather than anything eBay has spelled out:

• Ending and relisting a listing with sales history throws that history away. It is rarely a good way to 'refresh' a listing.
• Promoted Listings can help a new listing get its first sales, which then count as sales history. The ad placements themselves are separate from the organic results; eBay Promoted Listings covers when that is worth paying for.

Personalisation and location

eBay's buyer help page on how search works says results are ranked using factors that include the buyer's browsing history and the item's location, and that filters and sort choices change the results too.

So there is no single eBay ranking for a search. A buyer in Leeds and a buyer in Kent, or one who has been browsing a brand and one who has not, can see different orders. Searching for your own listing from your own account is a poor test, because your history is nothing like your buyers'. Use the impression and click-through figures in Seller Hub instead.

What eBay has not said

Several popular beliefs about Cassini have no official basis that I can find:

• That new listings get a temporary 'honeymoon' boost. Sellers report it; eBay has not documented it.
• That revising a listing resets its ranking. Editing the title or specifics changes how it matches, but there is no documented penalty for editing.
• That a shop subscription improves ranking. It is not among the factors eBay lists.
• That the time of day you list a fixed-price item matters for a listing that stays live until it sells.

Treat these as anecdotes. Test them on your own listings if you like, but do not build a process on them.

How Cassini differs from Google

Web SEO habits, such as stuffing a title with variations, work badly on eBay, where completeness and the likelihood of a sale count for more. How Google crawls and indexes a website is the useful contrast if you also run your own shop.

Next step

Open Seller Hub's traffic report for your top twenty listings and sort them into the three symptoms in the table above: few impressions, few clicks or few sales. Each points to a different fix. If you would rather have that done across a whole catalogue, the eBay management service works through listings in that order, and the eBay listing optimisation showcase sets out the method.