The eBay Cassini search engine decides which listings buyers see when they search — and most sellers treat it like a black box. It isn't. The algorithm has been documented in patents, eBay seller-hub guidance, and a decade of community testing, and the inputs that move rank are knowable. This guide breaks down how Cassini ranks listings in 2026, which signals matter most, and the operational levers you can actually pull to climb in Best Match.
What Cassini Actually Is
Cassini is the search and ranking engine that powers eBay's Best Match sort — the default order buyers see for nearly every query. It replaced the older Voyager engine in 2013 and has been rewritten several times since (see eBay's own seller-hub listing guidance for the official surface-level documentation). Unlike Google, which ranks documents from across the open web, Cassini ranks listings from a closed catalog where every seller follows the same template (title, item specifics, images, price, shipping, returns). That constraint changes the optimization game: Cassini can compare listings on hard structured data, not just unstructured text.
The engine sits between two populations. On one side: roughly 1.7 billion live listings. On the other: every search query a buyer types. Cassini's job is to score each candidate listing against the query, then present the ones most likely to convert at the top.
The single most important sentence to internalise: Cassini optimises for buyer outcomes, not seller preferences. Every ranking factor folds back into one question — "if we show this listing to this buyer, will they click, buy, and stay happy?"
The Three Pillars of Cassini Ranking
Every signal Cassini uses fits into one of three buckets. Understanding the bucket structure stops the endless game of chasing rumours about individual tweaks.
1. Relevance
Does the listing match what the buyer typed? Cassini checks the query against the title (heaviest weight), item specifics (rapidly growing weight), category, brand, MPN, and to a lesser extent the description. Item-specific matching is what lets eBay show the right listing when a buyer adds a filter on the left rail — and missing item specifics quietly removes you from those filtered result sets entirely.
2. Performance
Has this listing — or this seller — converted well historically? Cassini tracks click-through rate (CTR) on the listing impression, sell-through rate (sales ÷ impressions), watch and save rates, and seller-level metrics like defect rate, late-shipment rate, and feedback score. A listing that gets 4% CTR will outrank a listing with the same title at 1% CTR. Sellers with Top Rated status get an additional ranking boost. For dropshippers, this is exactly where Ecomli's automated reprice engine and 15-minute stock monitor pay off — they hold sell-through and defect rates inside Cassini's reward band without manual babysitting.
3. Buyer Experience
Will the buyer have a smooth post-purchase experience? Cassini rewards free or fast shipping, generous return windows (30 days or longer), accurate handling time, complete and high-quality photos, and listings priced competitively against the rest of the search result page. Listings that miss the mark on these signals get suppressed even when they would otherwise be a perfect relevance match.
The Ranking Factors That Move the Needle in 2026
Not every signal is equal. Based on patent filings, eBay's own seller education, and the operational data we see across Ecomli accounts, here are the levers ranked by impact.
Title — Still the Heaviest Weight
The first 60–70 characters of your title carry the most ranking power. Cassini tokenises the title, matches tokens against the query, and weights early tokens higher. The structural pattern that wins: Brand → Model → Key Spec → Condition → Size/Variant. Drop the filler words (Wow, L@@K, Rare, Must Have) — they consume token slots without contributing relevance and tank CTR. Use all 80 characters, but use them on facts buyers actually search for. For a deep dive on how to research and place these tokens, see our guide to keywords for eBay listings.
Item Specifics — The Most Underrated Signal
Every category on eBay has a list of recommended item specifics. Filling them all is the single highest-ROI change most dropshippers can make. Two reasons: first, item specifics are how Cassini matches structured filter searches ("Men's Running Shoes → Brand: Nike → Size: 10 → Color: Black"). A listing missing the Color field is invisible to anyone who filters by color. Second, complete item specifics are now a required input for eBay's product-based catalog matching, which feeds the related-items carousel on competitor listings.
Audit your top 20 listings: how many have every recommended specific filled? If the answer is below 90%, that's your fastest win. Inside Ecomli, the listing builder pre-fills item specifics from the supplier feed and flags missing required fields before publish, so this stops being a manual chore.
Sell-Through Rate
STR (sales ÷ impressions over a rolling window) is the cleanest signal Cassini has that a listing is worth promoting. The system rewards listings that are already converting. This creates a virtuous cycle for proven products and a cold-start problem for new ones — which is why product research matters so much. Picking proven sellers from the start beats trying to optimize a poorly-chosen product later. Our eBay product research workflow walks through how to find products with proven demand before you list.
Click-Through Rate
CTR on the search results page tells Cassini your listing earned the click. The two highest-impact CTR drivers are the gallery image and the price. A clean white-background main image consistently outperforms a styled-scene image in eBay's grid view. Price needs to be inside the cluster of competing listings on page one — Cassini compares your price to the prices of the other listings shown for the same query, not to a category average. This is where dynamic repricing matters: a $34.99 listing in a search result page where the other 11 listings sit between $24.99 and $28.99 will get suppressed.
Shipping Speed and Cost
Free shipping gets a ranking boost. Same-day or 1-day handling time gets a ranking boost. Listings with eBay's "Fast 'N Free" badge convert better, which feeds back into the STR signal. For cross-border dropshippers this is the hardest signal to optimize, because supplier handling time often runs 2–5 days and ground shipping from China runs 7–14. The fix is supplier selection — choose suppliers with US warehouses or pre-vetted fast-handling SKUs. Our supplier vetting framework covers what to test for.
Returns Policy
30-day free returns is the threshold for the highest tier of Cassini's returns boost. Restocking fees and seller-pays-return shipping reduce the boost. Yes, this means absorbing more return costs — but the offset comes through ranking and CTR, both of which compound.
Seller Performance Metrics
Cassini applies a seller-level multiplier on top of listing-level signals. Top Rated Plus sellers get the largest boost, then Top Rated, then Above Standard. The metrics that matter: defect rate (target under 0.5%), late-shipment rate (target under 3%), cases closed without seller resolution (target under 0.3%), and tracking upload rate (target above 95%). This is why Ecomli's automated supplier order placement and stock-sync prevent the late-shipment and out-of-stock defects that otherwise drag account-level metrics below Top Rated thresholds.
Listing Recency and Velocity
New listings get a small "freshness boost" for the first 24–48 hours after publish. This is why successful sellers stagger their bulk uploads across the week instead of dumping 200 listings on a Sunday night. Velocity — the rate at which a listing accumulates views and sales after publish — also signals quality. A listing that gets 50 views and 3 sales in its first 24 hours will outpace one that needed two weeks to hit the same totals.
Description Quality
Descriptions carry far less weight than titles or item specifics, but they still matter for two reasons: Cassini does parse them for keywords (lower weight), and buyers who scroll into the description and stay longer signal engagement. Mobile-first descriptions matter — over 60% of eBay traffic is on mobile, and tables, iframes, or anything that breaks the mobile renderer hurts engagement metrics.
What Cassini Punishes
Some signals actively suppress rank, even when relevance is strong.
- Keyword stuffing in titles. Repeating the same brand or category word multiple times triggers a soft demotion. Cassini sees the repetition as low-quality and the buyer-side CTR data confirms it.
- Duplicate listings. Posting the same product across multiple listings to "increase coverage" gets all of them suppressed. eBay's duplicate detection is automated and applies a sitewide penalty to repeat offenders.
- Generic stock photos used by every other seller. When dozens of listings share the same supplier-provided image, Cassini downweights the cluster and rewards the seller who uploaded an original photo or a modified composite.
- Out-of-stock or paused listings. A listing that goes out of stock loses ranking history when it comes back. Better to stay in stock — which is the whole reason automated supplier monitoring exists.
- High return rates. If your return rate exceeds the category average, Cassini suppresses the listing. This is a category-relative signal, so a 12% return rate in apparel is normal but the same rate in electronics will hurt you.
An Operational Workflow That Aligns With Cassini
Knowing the ranking factors is half the battle. The other half is building a daily workflow that consistently feeds Cassini what it wants. Here's the loop most successful eBay dropshippers run.
1. Research before you list
Pick products with proven sell-through. A bad product cannot be SEO'd into ranking. Use sold-listings data to find items with healthy weekly velocity, then check the price range competitors hold and your supplier's landed cost to confirm the margin works.
2. Build the listing structure correctly
Title in the Brand → Model → Spec → Condition → Variant pattern. Item specifics filled to 100% of recommended fields. Five or more high-resolution images, white background on the main image, lifestyle/detail shots after. 30-day free returns. Handling time set to match what your supplier can actually deliver — overpromising on handling time triggers late-shipment defects, which are more expensive than the slower handling time itself. Ecomli's listing builder handles the title structure and item-specific completion automatically when you import from a connected supplier.
3. Stagger publish times
Spread bulk uploads across the week. Aim for the freshness boost to land during peak buyer hours for your category — typically Sunday evening through Thursday evening for general consumer goods. Avoid dumping 100 listings at once.
4. Monitor early-life metrics
For the first 7 days after publish, watch impressions, CTR, and watch counts. A listing with high impressions but low CTR has a title or image problem. A listing with high CTR but no sales has a price or trust problem. Iterate one variable at a time — change the title, wait 48 hours, measure. Ecomli's AI listing engine builds Cassini-optimized titles and item-specifics on bulk import, so the launch window starts with structured data already aligned to the algorithm — not a manual cleanup pass after the freshness boost has expired.
5. Reprice continuously
Cassini compares your price to the rest of the search result page in real time. Static prices lose to dynamic competitors. The right repricer respects a hard margin floor (so you never sell at a loss) and adjusts toward the median competitor price, not the lowest. Ecomli's reprice engine pulls live competitor prices, applies your margin floor, and updates listings on a defined cadence — see our repricer configuration guide for how to set the floors.
6. Defend account health
Track defect rate, late-shipment rate, and case rate weekly. A single bad week can knock you out of Top Rated for 90 days. Most account-health damage in dropshipping comes from out-of-stock orders that ship late or get canceled — automated stock monitoring on the supplier side prevents the root cause.
Common Cassini Misconceptions
The community wisdom on eBay SEO is full of legacy advice that no longer applies. A few of the worst:
"End your auctions on Sunday at 7pm." This was true in 2010 when most listings were 7-day auctions. In 2026, fixed-price listings dominate and Cassini's ranking is continuous. Publish time matters mainly for the freshness window, not for end time.
"Price as low as possible to win Best Match." Lowest price doesn't win — best price-to-conversion ratio wins. A $24.99 listing converting at 1% will lose to a $29.99 listing converting at 4%. Margin matters because Cassini optimises on revenue per impression, not price.
"Hidden keywords in the description boost rank." Cassini's description parser is a fraction of the weight it had in 2015, and white-text-on-white-background tricks are detected and suppressed. Spend the energy on the title and item specifics.
"More listings = more sales." Quantity helps until quality drops. 200 well-built listings outperform 2,000 sloppy ones because the sloppy ones drag down account-level performance signals. Scale through better products, not duplicate listings.
Frequently Asked Questions
How long does it take a new listing to rank on Cassini?
The 24–48 hour freshness boost gives new listings their first window. After that, ranking is driven by accumulated signals: CTR, watch rate, sell-through. A well-structured listing on a proven product typically settles into its long-term rank position within 7–14 days. Brand-new sellers without a track record take longer because the seller-level signal is still building.
Does revising a listing reset its ranking history?
Minor edits — fixing a typo, updating an item specific — do not reset history. Major changes — replacing the title, swapping the main image, changing the category — can trigger a partial reset because Cassini treats the listing as effectively new. If you need to overhaul a listing, end it and create a fresh one rather than revising in place.
Why do my listings show up for me but not for buyers?
eBay personalises search results, so your own listings often surface higher when you're logged in than they do for a buyer in another country or on a different device. Use an incognito window, switch to the buyer-side view, and check your true rank from a buyer perspective. Don't trust the rank you see while logged in.
Does paying for Promoted Listings hurt my organic Cassini rank?
No. Promoted Listings sit in a separate auction-style placement and do not penalise organic rank. In fact, the additional impressions and sales from Promoted Listings feed back into the listing's CTR and STR signals, which can lift organic rank over time. Our Promoted Listings playbook covers how to budget campaigns without burning margin.
How important is the description if Cassini barely reads it?
The description influences buyer trust and conversion, even if it carries little direct ranking weight. A clear, mobile-friendly description with size charts, materials, shipping details, and returns policy raises CTR-to-purchase conversion, which feeds the STR signal. Treat it as a conversion asset rather than an SEO asset.
What's the fastest single change I can make to improve Cassini rank?
Fill every item specific on your top 20 listings. It typically takes a few hours, requires no new tools, and most accounts see impression lift within a week because the listings start surfacing in filtered searches they were previously excluded from.
Ready to automate your eBay business and let Cassini do the rest? Ecomli handles bulk product import from AliExpress and Amazon, AI-written Cassini-optimized titles, automated reprice with margin floors, 15-minute stock and price monitoring, and automated order placement at the supplier — so the only thing left for you is product selection and scaling decisions.
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