eBay's Cassini Algorithm: A Guide to Search Visibility, Ranking Signals, and Recovery

In early May, something broke. Or at least, that's what thousands of eBay sellers thought when they opened their Seller Hub and saw impressions crater by thirty, forty, sometimes fifty percent. The Facebook groups lit up. Reddit threads multiplied. Everyone had a theory. eBay changed the algorithm. eBay shadowbanned established stores. eBay flipped a switch to force everyone into Promoted Listings Advanced. The word "Cassini" started getting thrown around like a curse word, as if it were some vindictive AI sitting in a San Jose server farm, personally deciding whose mortgage payment doesn't clear this month.

But here's the thing most sellers don't realize: Cassini isn't a new change. It isn't a switch someone flipped in May. It's eBay's search engine, and it's been running the show since 2013. The reason it feels like "the algorithm changed" every few months isn't because eBay replaces the whole system. It's because Cassini is constantly learning, constantly adjusting, and constantly weighing new signals against old ones. When your views drop off a cliff, it's usually not because eBay hates you. It's because the math shifted, and your listings stopped winning the auction for attention.

This guide provides a structured, data-driven analysis of how Cassini works, the signals it prioritizes, and practical strategies for maintaining and recovering search visibility.

Key Takeaways

- Cassini is not a new algorithm. It's been running since 2013. It constantly adjusts weighting, which makes it feel like "the algorithm changed" every few months.

- Relevance is the foundation. Boring titles with exact keywords outperform creative titles. Fill out every item specific field. Cassini matches text, not sentiment.

- Recency gives new listings a boost. That boost lasts 24 hours to 2 weeks. If a listing doesn't prove itself during that window, it sinks. Refresh stale inventory with Sell Similar.

- Seller performance is punitive. Top Rated sellers get a visibility bonus. Below Standard sellers get buried. One late shipment won't kill you, but a pattern will compound into a death spiral.

- Conversion rate drives long-term visibility. If buyers click and buy, Cassini shows you more. If they click and leave, Cassini stops showing you. Price and presentation matter for visibility, not just sales.

- Promoted Listings are increasingly mandatory in crowded categories. Flat 5% rates barely move the needle. Be strategic: let listings prove themselves organically for 30 days, then promote the ones that showed life.

- The May 2026 crash was a weighting adjustment. Not a conspiracy. Not a shadowban. eBay adjusted how heavily it values certain signals, and established stores got caught on the wrong side of the new math.

- Diagnose, don't panic. If impressions are steady but sales are down, your problem is price or presentation. If impressions are down, your problem is relevance, recency, or seller standing. The data tells you what to fix.

1. What Is Cassini?

Cassini is eBay's internal search and ranking engine. Its job is simple: when a buyer types "vintage Levi's 501 32x32" into the search bar, Cassini has milliseconds to decide which of the twelve thousand active listings gets shown first, which gets buried on page nine, and which doesn't get shown at all. It does this by scoring every listing against a set of signals, then ranking them by that score.

The signals aren't secret—eBay has actually published them. The problem is that nobody reads the seller updates, and eBay buries the technical details under marketing speak about "delighting buyers." Understanding these signals is the foundation of any effective visibility strategy.

2. Signal One: Relevance

Relevance is the most obvious signal. Does your title actually contain the words the buyer searched? Not sort of. Not creatively. Actually. If someone searches "Nike Air Force 1 white size 10" and your title is "Fresh Kicks 🔥 Rare Sneakers 🔥 Must See," Cassini has no idea what you're selling. It doesn't speak emoji. It doesn't understand "fresh kicks." It matches keywords, and it gives extra weight to the words in your title, your item specifics, and your structured data.

The Data:

Sellers who still write titles like they're crafting poetry are losing to sellers who write titles like they're filing a police report. Boring wins in search. A title that includes brand, model, size, color, and key features will consistently outrank a creative, keyword-poor title.

The Fix:

Fill out every item specific field. Empty item specifics are missed opportunities to match search queries. Use the exact keywords buyers are searching for, not synonyms. Cassini matches text, not sentiment.

3. Signal Two: Recency

This is where most established sellers get destroyed, and it's the hardest pill to swallow. Cassini gives a boost to newly listed items. Not because eBay wants to reward new sellers, but because new listings represent fresh inventory that might be exactly what buyers want. That boost usually lasts somewhere between twenty-four hours and two weeks, depending on the category and how buyers respond. If your new listing gets clicks and watchers during that honeymoon window, Cassini assumes it's good and keeps showing it. If it sits there getting ignored, the boost dies, and your listing starts sinking.

The Data:

Sellers who regularly refresh stale inventory—using Sell Similar or ending and relisting—see measurable bumps in impressions. The ones who let listings rot don't. This creates a brutal cycle for sellers with large catalogs. You list something. It gets a small burst of impressions. If it doesn't sell immediately, it drifts down the rankings until it's basically invisible.

The Fix:

Refresh stale listings. Use Sell Similar to trigger that new-listing boost again. Update photos, adjust prices to match current sold comps, and make sure item specifics are filled out completely. eBay won't admit this in plain English, but the data is obvious.

4. Signal Three: Seller Performance

This is where things get genuinely punitive. Cassini looks at your defect rate, your late shipment rate, your tracking upload rate, your return rate, and your buyer feedback. If you're Above Standard or Top Rated, you get a visibility bonus. If you're Below Standard, you get buried. Not shadowbanned. Buried. There's a difference. A shadowban implies someone manually targeted you. Cassini just lowers your score because your metrics suck, and listings with better seller scores outrank you. It's automatic, impersonal, and extremely effective at making bad sellers disappear.

The Data:

Sellers who drop from Top Rated to Above Standard often see a 10% to 15% dip in impressions without changing anything else. Sellers who hit Below Standard describe it as falling off the face of the earth. Their listings don't get removed. They just get ranked so low they might as well not exist.

The Fix:

The fix is boring and unsexy: ship on time, upload tracking within your handling window, describe your items accurately so you don't get returns, and answer buyer messages fast. Cassini rewards competence. It doesn't reward drama.

5. Signal Four: Conversion Rate

This is the signal most sellers ignore because it's not in their control panel. Cassini tracks what happens after someone clicks your listing. Do they buy? Do they bounce back to search in five seconds? Do they add to watch but never return? If buyers consistently click your listing and then buy, Cassini learns that your listing satisfies that search query. It starts showing you more. If buyers click and immediately leave—because your photos are bad, your price is too high, or your description is a wall of text with no measurements—Cassini learns that your listing is a bad match. It stops showing you.

The Data:

This is why pricing matters so much for visibility, not just for sales. A listing priced 10% above market might still get clicks from curious buyers, but if those buyers consistently leave without purchasing, your conversion rate drops, and Cassini demotes you. You didn't get shadowbanned. You got outcompeted by sellers whose prices converted better. The algorithm isn't emotional. It's just counting.

The Fix:

Monitor your conversion rate in Seller Hub. If impressions are steady but sales are down, your problem is price or presentation, not visibility. If impressions themselves are down, your problem is relevance, recency, or seller standing. Knowing which metric moved tells you whether to fix your listing or fix your account.

6. The Promoted Listings Factor

This is the signal everyone argues about, and the data from early 2026 made the picture clearer than eBay probably wanted. Promoted Listings aren't just an add-on anymore. They're increasingly baked into the ranking formula. In crowded categories, the top search results are dominated by ads. Not because organic results don't exist, but because eBay has financial incentive to prioritize paid placement. The January 2026 attribution change—where any click triggers a thirty-day fee window—made this even more explicit. eBay wants you to pay for visibility, and Cassini is designed to make unpaid visibility harder to hold onto as competition increases.

The Data:

Sellers running controlled tests show that promoting at a flat 5% rate, which used to provide a meaningful boost, now barely moves the needle in saturated categories. Sellers running 10% to 15% rates, or using Promoted Listings Advanced with keyword targeting, are capturing the premium placements. The organic slots that remain are fought over by listings with perfect metrics: great conversion, recent activity, Top Rated status, and strong relevance. If you're not paying and your metrics aren't flawless, you're fighting for scraps.

The Fix:

Be strategic about Promoted Listings. Don't auto-promote everything at a flat rate. Promote items that have proven organic demand but need a visibility push. Use the delayed promotion strategy—let listings prove themselves organically for thirty days, then promote the ones that showed life but didn't convert. Don't pay for ads on listings that have zero organic interest.

7. The May 2026 Crash: What Actually Happened

The May 2026 crash that so many sellers experienced? Look at the timing. It coincided with no announced algorithm update, which means it was likely a weighting adjustment. eBay tweaked how heavily Cassini values certain signals—maybe promoted placement, maybe recency, maybe seller performance thresholds—and a chunk of established stores got caught on the wrong side of the new math. Their listings weren't removed. Their accounts weren't banned. They just lost the ranking auction because the scoring changed and their listings didn't have the right combination of signals to stay visible.

The Lesson:

This is the reality of selling on a platform you don't control. Cassini isn't a static rulebook. It's a dynamic system that optimizes for eBay's revenue and buyer satisfaction, not your seller convenience. When eBay needs more ad revenue, Cassini can subtly increase the weight of promoted placements. When eBay wants to improve buyer trust, it can crank up the penalty for seller defects. These aren't conspiracies. They're business decisions, and your inventory's visibility is the lever they pull.

8. What You Can Actually Do

Refresh Your Listings:

Stop treating your listings like museum pieces. Use Sell Similar on stale inventory to trigger recency signals. Update your photos, adjust your prices to match current sold comps, and make sure your item specifics are filled out completely. Cassini loves structured data. Empty item specifics are missed opportunities to match search queries.

Protect Your Seller Metrics:

Protect your seller metrics like they're cash in the bank, because they are. One late shipment won't kill you, but a pattern of late shipments, untracked items, and unhappy buyers will compound into a visibility death spiral that no amount of promotion can fix.

Be Strategic About Promoted Listings:

Don't auto-promote everything at a flat rate. Promote items that have proven organic demand but need a visibility push. Use the delayed promotion strategy—let listings prove themselves organically for thirty days, then promote the ones that showed life but didn't convert. Don't pay for ads on listings that have zero organic interest.

Monitor Your Conversion Rate:

Watch your conversion rate in Seller Hub. If impressions are steady but sales are down, your problem is price or presentation, not visibility. If impressions themselves are down, your problem is relevance, recency, or seller standing. Knowing which metric moved tells you whether to fix your listing or fix your account.

9. The Bottom Line

The truth about Cassini is that it's neither your enemy nor your friend. It's a scoring system. It rewards listings that make eBay money and satisfy buyers. It buries listings that don't convert, that come from unreliable sellers, or that sit untouched for months. You can't hack it with keyword stuffing or conspiracy theories. You can only feed it better signals: fresher listings, accurate data, competitive prices, fast shipping, and honest descriptions.

Your algorithm anxiety won't change the ranking. But your data might. Open your Seller Hub. Look at your impressions graph for the last ninety days. Find the day they dropped. Then look at what changed in your store the week before. That's not paranoia. That's diagnostics. And it's the only thing that actually works.

Q&A:

Question: What is Cassini and why does it feel like it changes constantly?

Short answer: Cassini is eBay's search and ranking engine, in use since 2013. It doesn't get replaced, but it constantly adjusts how it weighs signals. When your views drop, it's usually because the weighting shifted and your listings lost the ranking auction, not because eBay targeted you.

Question: What are the most important ranking signals?

Short answer: Relevance (does your title match the search?), recency (new listings get a boost), seller performance (Above Standard and Top Rated get bonuses), conversion rate (do buyers buy after clicking?), and Promoted Listings status (paid placements increasingly dominate).

Question: Why do my impressions drop after a listing has been up for a while?

Short answer: The new-listing boost wears off after 24 hours to 2 weeks. If your listing didn't get clicks and watchers during that window, Cassini assumes it's not a good match and stops showing it. Refresh it with Sell Similar to trigger the boost again.

Question: Does Promoted Listings affect organic visibility?

Short answer: Yes. Promoted Listings are increasingly baked into the ranking formula. In crowded categories, organic results are often pushed down by paid placements. If you're not promoting and your metrics aren't flawless, you're fighting for scraps.

Question: What was the May 2026 crash?

Short answer: It was likely a weighting adjustment, not an algorithm replacement. eBay tweaked how heavily Cassini values certain signals—promoted placement, recency, seller performance thresholds—and established stores on the wrong side of the new math saw their rankings drop.

Question: What's the best way to recover lost visibility?

Short answer: Refresh stale listings with Sell Similar. Protect your seller metrics. Be strategic about Promoted Listings. Monitor your conversion rate. Diagnose whether the problem is relevance, recency, or seller standing, then fix the root cause.