eBay SEO: How Cassini Ranks Your Listings

eBay SEO is the process of optimising your listings so that eBay’s internal search engine, Cassini, surfaces them to buyers at the right moment. Unlike Google, which ranks web pages across the entire internet, Cassini is built around one goal: completing transactions. That changes almost everything about how you approach optimisation.

Most sellers treat eBay like a static catalogue. They upload a listing, set a price, and wait. The ones who understand how Cassini actually works treat every listing as a living commercial asset, and the difference in visibility is significant.

What Is Cassini and Why Does It Change the SEO Equation?

eBay introduced Cassini as its search engine in 2013, replacing the older Voyager system. The name is a nod to the Saturn probe, which was built to find things in complex environments. Cassini’s commercial logic is straightforward: eBay makes money when transactions happen, so it promotes listings most likely to result in a sale.

This is a fundamentally different brief from Google’s algorithm, which has to balance relevance, authority, user experience, and a dozen other signals across billions of pages. Cassini is narrower and more mercenary. It is asking, at every moment: which listing will this buyer most likely purchase from?

That means your click-through rate, conversion rate, sell-through rate, and seller metrics all feed into your ranking in ways that keyword matching alone cannot override. I have seen this dynamic play out in paid search too. When I was running iProspect and managing large-scale ad accounts, the platforms that tied quality scores to conversion behaviour always punished listings that looked good on paper but underperformed commercially. Cassini applies the same logic, just on a marketplace level.

If you want a broader framework for thinking about search optimisation across channels, the Complete SEO Strategy hub covers the underlying principles that apply whether you are optimising for Google, Amazon, or eBay.

How Do eBay Titles Actually Work as a Ranking Signal?

eBay gives you 80 characters for a listing title. That is not a lot of room, and most sellers waste a third of it on words buyers never search for.

The title is the primary keyword field Cassini reads. There is no hidden keyword tag, no meta description, no H1 in the traditional sense. The title is where your searchable terms live, and you need to treat every character as inventory.

A few principles that hold up in practice:

Lead with the most important keyword. Cassini reads titles left to right and weights terms accordingly. Put the product name, brand, and model number at the front. “Nike Air Max 90 Men’s Trainers Size 10 White” outperforms “White Men’s Trainers Nike Air Max 90 Size 10” because buyers searching for Nike Air Max 90 get the match immediately.

Use buyer language, not seller language. Sellers often describe products the way manufacturers do. Buyers search the way they talk. If you are selling a second-hand camera, “used” or “pre-owned” is what buyers type, not “previously enjoyed” or “gently used.” Check eBay’s own search suggestions, which surface real query patterns, before finalising your title.

Stack attributes, not adjectives. Colour, size, condition, compatibility, model number. These are searchable. “Stunning,” “beautiful,” and “rare” are not. Every adjective that adds no search value is a wasted character.

Do not keyword stuff. Cassini penalises titles that look like a string of unrelated search terms. “iPhone Samsung Sony Laptop Tablet Electronics” will not help you rank for any of them. Relevance is still a signal.

The subtitle field (available for a small fee) gives you an additional 55 characters that appear in search results but do not contribute directly to keyword ranking. Use it for conversion copy, not keyword repetition.

What Are Item Specifics and Why Do Most Sellers Get Them Wrong?

Item Specifics are the structured data fields eBay provides for each category: brand, colour, size, material, compatible model, MPN, condition, and so on. They are one of the most powerful ranking levers on the platform and one of the most consistently neglected.

When a buyer uses eBay’s left-rail filters to narrow results by brand, size, or condition, Cassini only shows listings that have those specifics completed. If you have left them blank, you are invisible to that filtered search, regardless of how good your title is.

eBay has been vocal about the importance of Item Specifics for several years now, and Search Engine Journal noted eBay’s growing investment in SEO infrastructure as part of a broader push to improve search quality across the platform. The direction of travel is clear: structured data wins.

The practical advice here is simple but time-consuming. Go through every listing and fill in every relevant Item Specific field, even the optional ones. eBay’s own data suggests that listings with more complete specifics rank higher and convert better. The algorithm is not subtle about rewarding completeness.

For categories like clothing, electronics, and automotive parts, the specifics fields are extensive. Build a template for each product type you sell so you are not starting from scratch with each listing.

How Do Seller Metrics Feed Into Cassini Rankings?

This is where eBay SEO diverges most sharply from traditional search optimisation. On Google, your server uptime does not affect your rankings. On eBay, your defect rate does.

Cassini factors in seller performance across several dimensions:

Defect rate. Transactions where the buyer opened a case, received an item not as described, or left negative feedback count against you. A high defect rate signals to Cassini that your listings are misleading or your products are poor quality, and your visibility drops accordingly.

Late shipment rate. eBay tracks whether you dispatch within your stated handling time. Sellers who consistently ship late get suppressed in search results. This is not a soft penalty. It is a hard algorithmic signal.

Cases closed without seller resolution. If a buyer opens a case and eBay has to step in to resolve it, that counts heavily against you. Resolve disputes before they escalate.

Feedback score and percentage. Positive feedback percentage matters more than raw feedback volume. A seller with 500 feedback at 99.8% positive will generally outrank a seller with 5,000 feedback at 97% positive in otherwise comparable listings.

I spent years working with clients who wanted to separate their brand experience from their operational performance, treating them as two different functions. They are not. On eBay, the algorithm makes no such distinction. Your logistics performance is your SEO performance. The two are the same thing.

What Role Does Sales Velocity Play in eBay Search Rankings?

Cassini weights recent sales velocity heavily. A listing that has sold five units in the past seven days will typically outrank a listing that sold fifty units six months ago but nothing recently. This is the platform’s way of surfacing what is commercially active and in demand right now.

The implication for sellers is that dormant listings decay. If you have inventory that has not moved in months, its ranking will have drifted downward regardless of how well-optimised the title and specifics are. You have a few options to address this.

Relisting can give a listing a temporary boost, as eBay treats a new listing as fresh. However, this resets your sales history, which is a trade-off worth considering for listings with strong conversion records.

Promoted Listings, eBay’s paid advertising product, can accelerate early sales velocity for new listings, which then feeds into organic ranking. This is a legitimate use of paid spend, not just a shortcut. You are buying data and momentum, not just clicks.

Pricing adjustments can also stimulate velocity. A modest price reduction that triggers a sale resets the clock on your recent activity signals. The commercial maths need to work, but if you are sitting on slow-moving stock, a temporary margin sacrifice to restore ranking can pay back over time.

How Should You Write eBay Listing Descriptions for SEO?

The description field carries less direct ranking weight than the title and Item Specifics, but it is not irrelevant. More importantly, it is where you convert the buyer who clicked through from search results.

Cassini does index description content, and for queries where the title does not contain the exact search term, the description can help surface the listing. This matters most in long-tail searches where buyers use very specific phrases that would not fit in an 80-character title.

From a conversion standpoint, the description needs to answer the questions a buyer would ask before purchasing. Condition details, dimensions, compatibility, what is included in the box, and any known defects for second-hand items. Ambiguity in descriptions drives up buyer questions and returns, both of which hurt your seller metrics and therefore your rankings.

Keep descriptions clean and scannable. Bullet points work well. Avoid walls of text. eBay buyers are often comparing multiple listings simultaneously, and they will not read a paragraph-heavy description when a competitor’s listing answers their question in three bullet points.

One thing worth noting: eBay has been reducing the prominence of HTML-heavy descriptions in its mobile interface. Overly formatted descriptions with complex tables and embedded images can render poorly on mobile, which now accounts for the majority of eBay traffic. Simpler is more strong.

How Do eBay Promoted Listings Interact With Organic Rankings?

eBay’s Promoted Listings Standard product operates on an ad rate model: you set a percentage of the sale price as your ad fee, and eBay promotes your listing in additional placements across the platform. You only pay the fee when a buyer clicks your promoted listing and purchases within 30 days.

The relationship between promoted listings and organic rankings is indirect but real. Promoted listings generate more impressions, which can generate more sales, which improves your sales velocity, which improves your organic ranking. It is a flywheel, not a straight line.

The mistake I see sellers make is treating promoted listings as a replacement for organic optimisation. They set a high ad rate, get visibility, and never fix their titles, specifics, or seller metrics. When they pause the promotion, their organic ranking is no better than when they started. Paid spend should accelerate an already-optimised listing, not compensate for a poorly built one.

Promoted Listings Advanced (PLA) operates more like traditional pay-per-click, with keyword targeting and cost-per-click bidding. This gives you more control over which searches trigger your listing but requires more active management. For high-volume sellers with strong margins, it is worth testing. For casual sellers, Standard is simpler and lower risk.

What Can You Learn From Competitor Listings on eBay?

Competitive analysis on eBay is more transparent than on most channels. You can see exactly what your competitors are doing: their titles, their prices, their feedback scores, their Item Specifics, their sell-through rates on completed listings, and their promoted listing activity.

The completed listings filter is particularly valuable. By searching for your product and filtering for completed listings, you can see which listings actually sold and which did not. This tells you far more than looking at active listings, where everything looks equally “available.” Sold listings are proof of commercial performance. Unsold listings are just inventory.

When I judged the Effie Awards, one of the persistent problems I saw was entrants presenting correlation as causation. They would show that sales went up during a campaign and claim the campaign drove the result. The same trap exists in eBay competitive analysis. A competitor’s listing might be ranked highly because of their sales velocity, their feedback score, or their account age, not because their title is better than yours. Identify what is actually driving their ranking before you copy their approach.

Look at the top three to five listings for your target search term. Note what they have in common in terms of title structure, price point, Item Specifics completeness, and seller rating. Then assess where your listing falls short on those dimensions. That gap analysis is more useful than any keyword tool for eBay specifically.

How Do Returns Policies and Shipping Options Affect Cassini?

eBay actively promotes listings from sellers who offer free returns and free postage, because these options reduce buyer friction and increase conversion rates. Cassini rewards the behaviours that make buyers more likely to purchase.

Free postage listings get a ranking boost in Best Match. This does not mean you absorb the postage cost out of margin. It means you build the postage cost into your item price and offer free postage. Buyers respond better to a £25 item with free postage than a £20 item with £5 postage, even though the total cost is identical. eBay’s algorithm reflects this buyer psychology.

Returns policy affects conversion more than ranking directly, but conversion feeds ranking. Listings with no-returns policies convert at lower rates, which signals to Cassini that the listing is less commercially effective. A 30-day free returns policy is the eBay standard that buyers expect in most categories. Deviating from it without good reason costs you visibility.

Same-day or next-day dispatch is another signal. eBay badges listings with fast handling times, and buyers filter for them. If you can commit to same-day dispatch for orders placed before a certain time, do so. It improves both your click-through rate and your seller metrics.

What Are the Most Common eBay SEO Mistakes?

After seeing how marketers approach optimisation across dozens of industries, the mistakes on eBay tend to cluster around the same few misunderstandings.

Treating eBay like Google. The signals are different. Domain authority, backlinks, and page speed are irrelevant. Sell-through rate, seller metrics, and Item Specifics completeness are not. Applying a Google SEO mental model to eBay will send you in the wrong direction.

Ignoring the mobile experience. Most eBay traffic is mobile. Descriptions that look fine on desktop can be unreadable on a phone. Test your listings on mobile before publishing.

Setting and forgetting. eBay listings are not static. Prices change, competitors enter the market, and your sales velocity decays over time. Treat your listings as assets that need regular review, not tasks that need completing once.

Misreading the data. eBay’s seller hub provides impressions, clicks, and sales data at the listing level. Sellers often optimise for impressions (which measures reach) when they should be optimising for conversion rate (which measures commercial effectiveness). A listing with high impressions and low conversions has a relevance problem or a price problem. More impressions will not fix it. Moz’s analysis of failed SEO tests makes a similar point about misreading the relationship between traffic and results.

Neglecting account health. A single period of poor fulfilment can suppress your entire account’s visibility, not just the affected listings. Account health is a global ranking signal, not a per-listing one. Protect it accordingly.

The broader principles of search optimisation, from intent matching to conversion thinking, apply across channels. The Complete SEO Strategy hub is worth reading alongside this article if you want to understand how eBay SEO sits within a wider acquisition framework.

How Should You Approach eBay SEO as a Long-Term Strategy?

eBay SEO is not a one-time project. It is an ongoing operational discipline. The sellers who win over time are the ones who treat listing quality, seller metrics, and pricing strategy as interconnected levers rather than separate tasks.

Build a quarterly review process for your top-performing listings. Check titles against current search trends using eBay’s own search suggestions. Audit Item Specifics completeness. Review your sell-through rates and identify which listings have decayed. Compare your pricing against active competitors.

For sellers with large catalogues, this is not feasible manually. Third-party tools like Terapeak (now integrated into eBay’s seller hub for subscribers), Zik Analytics, and 3Dsellers can help you identify ranking opportunities and monitor competitor activity at scale. They are not a substitute for understanding how Cassini works, but they are useful once you have the fundamentals in place.

The sellers who struggle on eBay are usually the ones who have optimised for activity rather than outcomes. They have uploaded hundreds of listings, tinkered with titles, and run promoted listings campaigns, but they have not asked the fundamental question: why is this listing not converting? That question, answered honestly, is where eBay SEO actually starts.

I spent a long time in agency leadership watching clients confuse effort with effectiveness. The volume of work done was not the measure of success. The commercial outcome was. eBay is an unusually honest environment in that respect. The data tells you quickly whether your listing is working. The discipline is in acting on what the data says rather than defending the decisions you have already made.

About the Author

Keith Lacy is a marketing strategist and former agency CEO with 20+ years of experience across agency leadership, performance marketing, and commercial strategy. He writes The Marketing Juice to cut through the noise and share what works.

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