Why Use Google Comparison Shopping Services? An Introductory Guide

Are you new to the world of Google Comparison Shopping Services? Even for those with some experience of paid search advertising, the range of opportunities can seem overwhelming. Especially if you plan to work with multiple Comparison Shopping Service (CSS) partners.

Our introductory guide to Google CSS will help you cut through the complexity by explaining clearly how Google Shopping Ads work, what a Comparison Shopping Service actually is, and how working with a CSS can help you reach more people and increase incremental sales without impacting your current advertising costs.

Online retail is still growing enormously every year. In the UK it’s predicted to increase by more than 30% over the next few years, becoming a fifth of all retail sales by 2024. And 56% of British shoppers already use Google for discovery and recommendations

What are Shopping Ads on Google?

When you search for a product online, adverts from Google Shopping will be prominently displayed on the results page. The most common examples are Product Listing Ads (PLAs), which are typically displayed above the organic search results in a carousel format.

Google’s product comparison service originally launched as Froogle in 2002 offering free listings for merchants. Since then it has grown massively in importance and prominence to businesses, customers, and Google itself. 

The effectiveness of PLAs led to the introduction of a paid auction system for advertisers, and the available space increasing to up to 30 listings in one carousel. Shopping ads were originally triggered by very specific product search terms, but they are now activated by more generic keywords and phrases. And additional promotional options, such as Showcase Shopping ads, have also been introduced. These highlight a range of products from an individual brand.

All Google Shopping advertising is controlled at a product level, requiring a data feed to be created and uploaded to Google Merchant Center for Shopping Ad campaigns to be created.

It’s a form of advertising which has been embraced by both retailers and consumers. In 2018, around 80% of all paid search spending by retailers went to Google Shopping, and it received around 88% of all paid advertising clicks from customers. 

What are Google Comparison Shopping Services (CSS)?

A CSS partner is the only way to advertise on Google Shopping Ads.

Each Comparison Shopping Service is a website which collects product offers from retailers, and can place Shopping ads on behalf of merchants in countries which are part of the European Economic Area and Switzerland.

And this includes Google Shopping EU itself, which is required to operate as a standalone CSS business following a 2017 EU Commission ruling. It also ensures equal treatment and access for all Comparison Shopping Services. 

It’s tempting to use Google Shopping EU by default. But the requirement to operate with a profit means that it charges a fixed 20% fee per bid. Other CSS partners can charge different amounts, or use an alternative billing model which doesn’t require payment until sales are made.

The differences between CSS providers comes from how each one works with clients, additional technology and services offered, and their levels of expertise.


How do Google Shopping Ads work?

The Comparison Shopping Services (CSS) Partner can bid for Shopping ad placements on behalf of the merchant. Whichever merchant wins the advertising auction will then pay a cost per click based on the next highest bid. So, if your CSS bids 50p, and the next merchant bid is 30p, when your advert is clicked the cost will be 31p. This means your costs cannot be artificially increased. 

The other factors for displaying your adverts are the relevance and quality score for your product and information.

Campaigns are enabled by providing a product data feed, which is then uploaded to Google Merchant Center. All campaigns need to meet Google’s Shopping ads policies and product data requirements to be eligible.

When someone clicks on the product details in the advert, they will be directed straight to the relevant page of your website to make their purchase. Clicking on the credit ‘By RedBrain’ will take them to our RedBrain comparison site (for example) which also displays your products and directs customers to you for their purchases.


Are there different ways to work with a CSS partner?

There can be lots of factors involved in choosing a CSS partner, which are explored in detail below. But one of the core differences will be the way you work with a provider.

The three main routes to advertising via Google Shopping Ads with a CSS are self-service, a managed service, or a hybrid of the two.

For example, Google themselves offer a self-service model, but can also offer consultancy. The majority of RedBrain customers benefit from a Managed Service, although self service is offered to specific clients if required.

With self-service, the CSS will create the required Merchant Centre and Google Ads accounts on your behalf, and leave you to manage your feeds and campaigns.

A managed service will let your CSS optimise your product data feed and manage your campaigns, whereas hybrid models can be a mixture of the two approaches.

The other major difference between CSS partners is how they will bill you for the work they carry out on your behalf.

How do I pay CSS partners?

Every CSS partner will bill for their services based on one of three models. Either they will invoice a fixed monthly retainer, Cost-Per-Click, , or some, including RedBrain, offer a Cost Per Action (CPA) service which charges based on completed sales. Essentially you only pay a commission when you’ve received a new customer.

Ultimately your choice of CSS partner should be based on more than just their billing model. But a CPA model does show confidence in the results a CSS believes they will deliver for you.

Who can be a CSS Partner?

Every CSS has to meet minimum requirements to operate with Google Shopping. So your existing PPC or marketing agency is unlikely to qualify - but they can work with any CSS on your behalf.

To help in choosing the right provider, Google has introduced a CSS Partner and Premium CSS Partner program. This lists services who have been officially certified for their skills, training, and experience. In return for meeting the requirements, Premium CSS Partners such as RedBrain gain access to higher levels of support and training from Google, and are likely to get earlier access to new opportunities.

Since 2017, Google Shopping EU is listed as just one of the Premium CSS Partners you can choose by country, industry and supported language.

Fortunately, the decision of picking a CSS has been made easier by the design of the Shopping Ads auctions, which allow you to use multiple partners at the same time, without increasing your costs. In fact for most large retailers it can be beneficial to work with multiple providers.

Is it best to use one or many CSS partners? Should you mix models?

For the vast majority of merchants it’s best to use multiple CSS partners and bidding strategies. This will enable you to reach the biggest possible audience, as the efforts of each provider will be complementary rather than antagonistic. So you get the best of the results from each service.

Providers may rely entirely on human expertise to choose key products to feature, create campaigns and manage bidding. This will operate differently to a service such as RedBrain, which adds skilled staff on top of a machine learning AI platform and Smart Bidding to scale our insight to a larger range of your product inventory.

It also opens up the opportunity to appear more than once on a single results page. Although two CSS services can’t both appear for the exact same product from one retailer, it’s possible that two different products might both qualify. Or you could appear in two Showcase Shopping ads because you’re working with both CSS partners.

But won’t CSS models and partners compete?

No matter how many CSS suppliers you are working with, a specific product will only appear once. However, different products from the same merchant can be displayed via multiple CSSs in the same advertising unit.

If multiple CSS partners all bid on the same product, from the same merchant, it’s treated as coming from the same CSS. This means that a merchant never pays more for advertising due to having two or more CSS providers. Instead, the merchant never pays more for advertising with multiple partners. So, you pay the same price based on the next highest bid, as the following Google example shows, no matter how many CSSs work on your account. The top two bids are made on the same offer (the same product from the same merchant), by two CSS providers. But the second bid is removed from the calculation of the price paid.

In 2018, a second Comparison Listing Ads carousel was also introduced. This additional advertising placement shows a selection of products available from each relevant CSS provider. It’s triggered if enough examples are available for a specific product or phrase, providing another promotional channel only available via a CSS partner.

PULL OUT QUOTE: “If multiple CSS partners all bid on the same product, from the same merchant, it’s treated as coming from the same CSS so the merchant never pays more for advertising with multiple partners.”

CSS providers are also able to access Smart Shopping campaigns which give access to additional advertising placements. These include Local Inventory ads, and display advertising on the Google Search Network, Display Network, Youtube and Gmail.

How to choose a CSS partner?

If you can work with one or more providers, how do you go about choosing a CSS supplier? The key differences between Comparison Shopping Services include:

  • Service models
  • Bidding Strategies
  • Experience and expertise
  • Additional Services
  • Billing models
  • Reach
  • Technology

Service Models: A Managed Service will let you provide your product data directly to your CSS, and they handle optimising your feed, uploading it to Google, and managing your campaign. Self-Service means you manage your Merchant Centre and Google Ads accounts once they’ve been created by your CSS.

Bidding Strategies: Each CSS will have their own approach to effective bidding. Some will focus on specific products rather than your whole inventory, or go through manually creating account structures and bidding optimisation. Whereas the RedBrain machine learning and AI approach works through the day and night to implement Smart Bidding on every product.

Experience and expertise: This doesn’t just apply to implementing bidding. In addition to the quality controls and requirements enforced by Google, pan-European campaigns require a knowledge of the laws and product restrictions in each country.
This comes largely from experience, working with thousands of retailers on a daily basis and providing solutions for every challenge they might encounter.

Additional Services: Data enhancement and optimisation can deliver a big increase in sales conversions. And the wealth of data from a Premium CSS Partner can feed into your other marketing efforts, along with providing answers to any queries or problems which may occur.

Billing Models: Many CSS providers will operate on a Cost-Per-Click (CPC) basis with an additional fee on your bids or a monthly retainer. For example, Google Shopping will add a 20% charge onto bids before they are entered into the advertising auction. But it’s possible for an optimised campaign to be run on a CPA basis, which means you only pay a commission when you make a sale.

Technology:  If you stock thousands of products, it will take a huge amount of time and manpower to scale optimisation across your inventory. This means AI, machine learning and automation are essential, in combination with expert oversight and input, to promote everything you sell effectively.

Reach: Experience and huge amounts of data come with scale, allowing your CSS to benchmark your efforts and understand where the biggest improvements can be made. Look for partners who have worked with high volumes in the industries and regions which apply to your business. One key comparison will be the size and reach of each CSS website. Does it reach millions of visitors who will also be directed to purchase your products?

Ultimately you’re unlikely to lose anything in trying a new CSS partner. It’s fairly quick and easy to run trials and test performance in just a few weeks. From that you can find your optimal Digital Shopping Mix which offers the best combination of results.

Does Google Shopping restrict content or product types?

The vast majority of retailers are able to advertise their product ranges across Google Shopping, but there are some restrictions on inventory and editorial content.

Basic editorial standards apply to all Google advertising, including accurately displaying the URL or the landing page, avoiding using letters and symbols in odd ways to attract attention, and advertising websites which are not working.

Products which are prohibited include potentially harmful items including fireworks, tobacco or unapproved healthcare supplements. Products which can be displayed, but on a more limited basis, include alcohol and healthcare inventory which will need to meet the laws and regulations of the countries you are targeting.

You can find more details of the requirements and restrictions in the Google Shopping Ads Policy Center.

It’s important to ensure that your product data feed is kept accurate and valid as Google will regularly check information is correct. Issues can happen due to stock availability, price changes or making changes to your website and product IDs. A good CSS partner will be able to advise you on issues you may encounter before they occur.

How to be successful with Google CSS:

There are two main areas which form the basis for success with Google CSS. The first is the quality of your business offering, and the second is your partner strategy.

Fortunately, the best practice for Comparison Shopping Services matches up closely with a good general eCommerce business plan. That means it will also improve your results in other areas of marketing, including other Google Shopping and Paid Search advertising, and organic Search Engine Optimisation.

The starting point will be to ensure your business meets all the requirements to advertise. And to assess the quality and performance of your website. A good indication of success with Google CSS is an effective existing conversion rate, as this shows increasing visitors will be likely to result in more sales.

Your inventory should be competitively priced. And the product information should be enhanced with good quality images and reviews from previous customers. Stock availability is also important, particularly as it can create issues with your data feed.

The other indication for success is that there is sufficient consumer demand for your products. This can be shown by the search volume for individual items, or the product category.

A successful partner strategy will depend largely on the size of your business. For bigger or strong niche brands, working with multiple CSS partners will deliver the best results.

If you’re a smaller brand with less inventory, then there may not be enough differentiation between providers, so it will be better to focus on working with one CSS. You’ll still benefit from making the most of the available search volumes, and be best placed to increase sales as your business grows or your industry niche expands. Choosing a Premium CSS Partner will ensure a higher level of customer service and experience due to the eligibility requirements Google has, so it will save you trialling multiple providers.

You have 4 levers to drive success with Google CSS.

  • Your Offering: Quality website, products and data feed, with a good existing conversion rate
  • Your Competitiveness: Products are priced well, with good reviews and availability
  • The Market  Demand: Customers are actively looking for products and there’s sufficient search volume.
  • You CSS Strategy: Picking the right partners, brand and marketing strategy, and the right commission rates (for our managed CSS services)

In Summary: Why use Google CSS?

There’s never been a better time to benefit from the opportunities of Google Shopping with a CSS partner. Online retail continues rapid growth in the UK and around the world, meaning an ever-increasing customer volume through search. And this is being served by the evolution of Google Shopping ads to provide more ways for brands to be seen and enable sales.

Larger and more established Premium CSS Partners have the experience, technology and scale to provide optimisation and AI-powered bidding strategies capable of managing campaigns for even the largest businesses. And the variations in between providers mean that every retailer can find a great solution by easily creating the right Digital Shopping Mix.

If you’re ready to benefit from Google CSS partners, the next steps are:

  • Check your products don’t violate the Google Ads Shopping Policy
  • Contacting Google Premium CSS partners to find out more about their Services.
  • Auditing your website to ensure you have a quality offering with competitive products. Your prospective CSS partner may be able to advise you of any obvious issues based on their experience dealing with thousands of retailers.
  • Look at the requirements for creating your Product Data feed for uploading by you, or your CSS, ensuring your internal or external developer resource meet the recommendations from both Google, and anything your CSS partner advises.
  • Then test, test, test until you have your optimal Digital Shopping Mix


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