Introducing the WEM Price Compare Chrome Extension — Beat Amazon and eBay Prices on the Page You're Already On

The WEM Price Compare extension is now live on the Chrome Web Store. If you shop on Amazon or eBay in the UK, it answers one question every time you land on a product page: is the same item cheaper somewhere else right now? This piece explains what the extension does, what it deliberately does not do, where it fits in the wider UK and European price-comparison landscape, and why we built it the way we did.

The everyday problem

Most British shoppers default to Amazon or eBay for the convenience. The catalogue is enormous, the delivery is fast, and the checkout is one click. The trade-off is that Amazon and eBay rarely have the lowest price on any given item — they have the easiest one. A pair of Nike Air Force 1 trainers that costs £114.99 on one site might be £99.99 with a free returns policy at Foot Locker UK; a Samsung kettle on Amazon at £64 might be £49 at Argos with click-and-collect. Most of the time, you never see those alternatives because checking each retailer manually is too tedious.

That gap — between the convenience of one shop and the savings spread across many — is exactly what a price-comparison browser extension is supposed to close. The category is not new. Honey, Capital One Shopping, and similar tools have existed for years. The problem is that most of them have, over time, prioritised their own affiliate attribution over the shopper. They redirect your checkout, claim your existing affiliate cookie, and quietly insert themselves between you and the merchant. The result is that a tool which started as a shopper benefit has become, for many people, a tool to be uninstalled.

What WEM Price Compare does

The extension activates only on Amazon and eBay product pages — specifically Amazon.co.uk, Amazon.com, eBay.co.uk, and eBay.com. When you land on a product page, a small panel appears in the corner showing whether the same item, or a close match, is available cheaper at any of the retailers WEM covers. If a cheaper option exists, you tap through and complete the purchase on that retailer's own site. If no cheaper option exists, the panel stays out of the way and you finish your purchase wherever you started.

The retailers we currently compare against include Amazon, eBay, AliExpress, Foot Locker UK and NordVPN. The list grows as new affiliate partnerships approve — high-street names like Currys, Argos, Boots and AO are in the approval pipeline and switch on automatically once each programme confirms.

Pricing data comes from official affiliate-network feeds — primarily Awin, with additional coverage from CJ Affiliate, Partnerize, and Impact. These are the same product feeds the retailers themselves publish to their partner publishers, so prices and stock status are live. We do not scrape retailer websites; that approach is fragile, often violates terms of service, and produces stale data when a retailer redesigns its product pages.

What it deliberately does not do

There are four things WEM Price Compare will not do, by design. We think these are the points where the price-comparison-extension category as a whole has lost shopper trust, and we have built the extension around the opposite of each.

First, no checkout hijacking. When you click an alternative retailer in our panel, you go to that retailer's product page. We do not redirect you through a tracking domain that overwrites the cookie of an affiliate you were already supporting; we do not insert ourselves between you and the merchant's checkout. The retailer gets your business cleanly.

Second, no coupon auto-application. The extension does not pretend to find you a working discount code at checkout — a behaviour that has been widely demonstrated to fail more often than it succeeds, and which is the single most common cause of cart-abandonment caused by extension interference.

Third, no account required. There is no signup, no email, no password, no wallet. The extension stores one anonymous random ID per install in your browser's local storage so we can debug crashes; that is the entire user model. We do not link the install to a person.

Fourth, no browsing-history collection. The extension only runs on Amazon and eBay product-page URLs, and it requests only the two narrowest Chrome permissions available — activeTab (which exposes the current tab's URL only when you actively interact with the extension) and storage (for the anonymous ID). The extension cannot see, and does not collect, anything you do on other websites.

Where this fits in the European price-comparison landscape

Britain is unusual in the European price-comparison map. Most countries on the continent have one or two dominant homegrown comparison engines: Idealo dominates Germany, PriceRunner is the household name across the Nordics and increasingly the UK, Skroutz owns Greece, Trovaprezzi covers Italy, Comparis is the default in Switzerland, and Kelkoo and Google Shopping have overlapping reach across most markets. Industry roundups like Webappick's review of European price-comparison sites tend to focus on these regional incumbents — and they are right to, because each is genuinely strong inside its home market.

What is missing from those roundups is a UK-focused option that lives where shoppers actually shop. Most of the European comparison incumbents are destination websites: you go to them, type a query, and click through. That model works well when shoppers think to use it. The reality is that most British shoppers do not start a purchase at a price-comparison site — they start it on Amazon or eBay, and if the price seems reasonable, they buy. By the time they remember to check whether it is cheaper elsewhere, the moment has passed.

A browser extension is the only way to close that gap. It puts the comparison where the shopper already is, in the moment the buying decision is being made, without asking them to change their habits. WEM Price Compare is built for that pattern specifically: enhance the Amazon and eBay shopping flow rather than replace it. We surface our comparison data on those two destinations because that is where most UK shoppers are when they need it.

How to install and what to expect

Installing takes about ten seconds. Search the Chrome Web Store for "WEM Price Compare" or follow the install link from the extension page on wem3.ai. Once installed, the extension is dormant until you visit an Amazon or eBay product page; it will not run anywhere else. There is no onboarding flow and no settings panel — it just works.

On your first product page, the panel appears in the corner. If we have a comparison match, you will see between one and three alternative retailers with their current price. The strongest match is the top row, which is normally the cheapest in-stock option. Click any retailer name to open their product page in a new tab.

A few things to expect honestly. The extension will not always find a cheaper alternative. For genuinely Amazon-exclusive products, or for items where Amazon's price is already the lowest, the panel will say so and step out of the way. For some niche or vintage items on eBay, we will have no match at all. The extension is most useful in the categories where many UK retailers stock the same product line — fashion, footwear, electronics, kitchen appliances, beauty, home, fitness, and gaming.

Privacy in plain English

Because privacy in browser extensions is opaque even when documented, here is the entire data flow in three sentences. When you visit an Amazon or eBay product page, the extension reads the product title from that page (and only that page) and sends it to our servers as a search query. Our servers return matching products from our partner-retailer feeds. The only data we store about your install is one randomly generated string that lets us count active installs and debug crashes — no IP address, no email, no browsing history, no cross-site tracking.

The extension's permissions reflect this exactly. It requests activeTab and storage and nothing else. If at any point we need to expand permissions, we will tell you in advance and explain why; otherwise, the surface area stays as small as it is today.

What is next

The first 90 days of any extension launch decide its trajectory. If the comparison data is genuinely useful, early users tell people, leave reviews, and the extension compounds. If not, it stalls. We would much rather hear that something does not work than have you uninstall silently — there is a feedback link in the extension's popup that goes directly to our team, and emails to [email protected] are read.

On our side, the next set of additions are a price-history view (so you can see whether today's Amazon price is genuinely a deal or a return to baseline), price-drop alerts on items you bookmark, and expanded retailer coverage as more affiliate programmes approve. Bookmarked-item alerts in particular are the most-requested feature already, so that is the next ship.

A note on what we earn

WEM earns a commission when you buy through some of the retailers we link to, paid by the retailer or the affiliate network rather than by you. This commission is how the extension stays free, and it does not change the price you pay. The full disclosure is at wem3.ai/disclosure. We do not change ranking based on commission size; the cheapest in-stock match is always the top result, regardless of which retailer pays us most.

Install link, full retailer list, and feedback channel: wem3.ai/extension. Built in the UK, for UK shoppers.