Ecommerce Advertising Platforms: Retail Media for Marketplaces and Sellers

Retail media platforms: how marketplaces monetize their sellers

Retail media is advertising sold on a retailer's or marketplace's own pages, using that operator's shopper data. For a marketplace with a large seller base, sponsored ads are the natural way to monetize it: sellers already compete for the same shopper, so letting them bid for visibility turns that competition into ad revenue for the operator.

A marketplace has three realistic routes:

• Build in-house. Full control of the auction, data and ad formats, but it needs an ad-serving, bidding and reporting stack plus a team to run it. Amazon Ads and Walmart Connect are the best-known examples of this model.
• License ad tech. A vendor supplies the sponsored product auction, onsite placements and reporting under the operator's brand. Faster to launch, with less control over the roadmap.
• Add off-site demand. The operator connects its audiences to programmatic buyers so advertisers can reach its shoppers beyond its own pages.

reMKTR is not a platform you license to run your own marketplace ad network. We buy Amazon DSP for advertisers as a managed service. If you are an operator choosing ad tech, you will want a vendor built for that job, and this page's checklist below applies to them too.

What to compare when choosing a retail media platform

Whichever side of the table you sit on, these are the questions that separate platforms:

• Ad formats. Sponsored products in search and on product pages, banners, video, and off-site display. More formats give advertisers more ways to spend.
• Measurement. Does reporting show sales caused by the ad, or only sales that followed it? Ask who designs and computes any incrementality test, and whether it is written into the contract.
• Self-serve or managed. Self-serve suits small sellers testing a budget. Managed service suits larger budgets where optimization is a full-time job.
• Demand and supply fit. For operators, how many advertisers the platform brings. For advertisers, whether the audience is the one you sell to.
• Fees and terms. Flat fee, percentage of spend, or CPM markup. Get fee changes in writing, from any vendor including us.

How marketplace sellers run ads on operator platforms

For sellers, the process is similar across marketplaces. Register as an advertiser through the seller account, set a budget, pick automatic or manual targeting, add the product, and set a bid. Sponsored product ads are billed per click, so you pay only when a shopper clicks.

Two habits matter more than the platform. First, check the search term report weekly and negate terms that spend without selling. Second, judge any platform on profit, not on the platform's own attributed sales: a sale the ad sat next to is not necessarily a sale the ad caused.

Once sponsored ads are working, the next layer is programmatic display and streaming. On Amazon, that is Amazon DSP, which reMKTR runs as a managed service.

What is ecommerce advertising, actually?

Ecommerce advertising is paying a platform to put your product in front of a shopper at a moment that's likely to end in a sale. That's it. Everything else — the targeting options, the bid types, the creative formats — is mechanics sitting on top of that one exchange: money for attention.

The confusion isn't the concept, it's the number of places it now happens. A search ad on Google catches someone typing a query. A sponsored product ad on Amazon catches someone already scrolling a category page with a cart. A display ad served through a demand-side platform (DSP) catches someone who isn't searching for anything at all, on a site or app that has nothing to do with your product. Same goal, three completely different jobs.

Most lists of "best ecommerce advertising platforms" are really lists of search engines and social networks with an ad product bolted on. That's fine as a directory. It doesn't tell you which job each one is doing for you, or how to tell if it's working.

The five jobs these platforms actually do

Group platforms by job, not by logo, and the choice gets simpler:

• Search (Google Ads, Bing Ads): captures demand that already exists. Someone typed the query.
• Social (Meta, TikTok, Pinterest): interrupts a scroll to create demand that didn't exist a second ago.
• Marketplace sponsored ads (Amazon Sponsored Products, Walmart Connect): converts a shopper who is already in a buying mindset on that marketplace.
• Programmatic display / DSP (Amazon DSP, StackAdapt, AdRoll): reaches shoppers off the marketplace entirely — retargeting, prospecting, CTV — before or after the search happens.
• Affiliate and creator: borrows someone else's trust to close the sale.

Almost every brand needs the first three. The fourth — DSP — is where most of the confusion in this category lives, because it's the hardest to measure with a last-click report and the easiest to either overrate or dismiss for the wrong reason.

How to judge a platform: a worked example

Don't judge a platform on its headline case study. Judge it on the whole book. Across 30 advertisers reMKTR ran through Amazon DSP in July 2026, the portfolio delivered a 6.04x return on ad spend — measured across every advertiser in that set, not the best line item pulled out to make a slide.

Here's how that number gets built, and why the pieces matter more than the headline: that book ran 78.4 million impressions at a $4.00 CPM, with a blended $1.42 cost-per-click. If you've seen a $0.41 CPC quoted for this category elsewhere, that figure is online-video only — it's real, but it's one format inside a much bigger mix, not the whole book. Blended cost per acquisition came out to $5.49 across 57,137 attributed purchases, and 20.1% of those purchases came from a shopper who had never bought the brand before.

That last figure is the one worth sitting with. A ROAS number tells you the campaign made money. It doesn't tell you whether that money came from people who would have bought anyway. New-to-brand rate is a proxy for incrementality — it's not proof, but it's a lot closer to the real question than ROAS alone.

The mistake almost everyone makes with attribution

The common mistake is running DSP and sponsored ads side by side, then crediting the same purchase to both on a last-click report. Sponsored ads sit closer to the purchase, so last-click hands them the win almost every time — even on purchases the display ad actually put in motion earlier in the week. The DSP campaign looks like it's doing nothing. It gets cut. The brand loses the exact layer that was bringing in new-to-brand shoppers, and nobody notices because the report never separated the two.

We've seen this exact overcounting inside our own book before it got fixed. The fix isn't a smarter attribution model — last-click can't be patched into proving incrementality, because it was never built to answer that question. It can only tell you what touched last, not what would have happened without the ad. The fix is reconciling DSP and sponsored ads in Amazon Marketing Cloud so they stop double-claiming the same purchase, and running holdout tests or matched-control groups where you actually withhold the ad from part of the audience and measure the gap.