Google Comparison Shopping Services: A Comprehensive Guide

Google Comparison Shopping Services: A Comprehensive Guide
Everything you need to know about Google Comparison Shopping Services (CSS) and how to make the most out of them.


This comprehensive guide will help you understand Google Comparison Shopping Services (CSS) and how to make the most of this powerful advertising tool. We will discuss various topics, including choosing the right CSS partner, different ways of working with a CSS partner, and how to optimize your success with Google CSS.

What are Google Comparison Shopping Services (CSS)?

Comparison Shopping Services (CSS) are websites that collect product offers from retailers and place Shopping ads on behalf of merchants in countries within the European Economic Area and Switzerland. Google Shopping EU operates as a standalone CSS business and is one of the many available CSS partners.

While it may be tempting to use Google Shopping EU by default, it charges a fixed 20% fee per bid due to the requirement to operate with a profit. Other CSS partners can charge different amounts or use alternative billing models that don't require payment until sales are made. The differences between CSS providers come from how they work with clients, the additional technology and services they offer, and their levels of expertise.

How do Google Shopping Ads work?

Merchants who want to show their adverts for specific keywords or products compete in an advertising auction. The winner of the auction pays a cost per click based on the next highest bid. The other factors that determine whether your adverts are displayed are the relevance and quality score of your product and information.

Campaigns are enabled by providing a product data feed that is uploaded to Google Merchant Center. 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 are directed to the relevant page of the merchant's website to make a purchase.

Every CSS must meet minimum requirements to operate with Google Shopping. Existing PPC or marketing agencies may not qualify, but they can work with any CSS on your behalf. Google has introduced a CSS Partner and Premium CSS Partner program, which lists services officially certified for their skills, training, and experience. Premium CSS Partners, such as Order Legend, 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 available by country, industry, and supported language. Fortunately, the design of the Shopping Ads auctions allows you to use multiple partners simultaneously, without increasing your costs. In fact, for most large retailers, it can be beneficial to work with multiple providers.

How to choose a CSS partner?

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, like our Google Ads on Autopilot app, allows you to provide your product data directly to your CSS, which handles optimizing 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 its approach to effective bidding. Some focus on specific products rather than your whole inventory, while others manually create account structures and bidding optimization. In contrast, Order Legend's machine learning and AI approach implements Smart Bidding on every product throughout the day and night.

Experience and expertise: 

This covers not only implementing bidding but also knowledge of the laws and product restrictions in each country for pan-European campaigns. This expertise comes largely from experience, working with thousands of retailers daily, and providing solutions for every challenge they might encounter.

Additional Services: 

Data enhancement and optimization can deliver a significant increase in sales conversions. The wealth of data from a Premium CSS Partner can feed into your other marketing efforts and provide answers to any queries or problems that may occur.

Billing Models:

Many CSS providers operate on a Cost-Per-Click (CPC) basis with an additional fee on your bids or a monthly retainer. For example, Google Shopping adds a 20% charge onto bids before entering them into the advertising auction. However, an optimized campaign can be run on a CPA basis, meaning you only pay a commission when you make a sale.


AI, machine learning, and automation are essential for effectively promoting and scaling optimization across a vast inventory. These technologies should be used in combination with expert oversight and input.


Experience and extensive data come with scale, allowing your CSS to benchmark your efforts and understand where the most significant improvements can be made. Look for partners who have worked with high volumes in the industries and regions relevant 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 relatively 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.

Different ways to work with a CSS partner

There can be many factors involved in choosing a CSS partner, 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, managed service, or a hybrid of the two.

For example, Google themselves offer a self-service model but can also provide consultancy. Most Order Legend customers benefit from a Managed Service, although self-service is offered to specific clients if required.

With self-service, like Order Legend, the CSS creates the required Merchant Centre and Google Ads accounts on your behalf, and you manage your feeds and campaigns. A managed service allows your CSS to optimize your product data feed and manage your campaigns, whereas hybrid models can be a mixture of the two approaches.

How do I pay CSS partners?

Every CSS partner bills for their services based on one of three models: a fixed monthly retainer, Cost-Per-Click (CPC), or some, including Order Legend, offer a Cost Per Action (CPA) service, which charges based on completed sales. Essentially, you only pay a commission when you receive an order.

Your choice of CSS partner should be based on more than just their billing model. However, a CPA model does show confidence in the results a CSS believes it will deliver for you.

Can I work with multiple CSS partners?

For most merchants, it's best to use multiple CSS partners and bidding strategies. This approach enables you to reach the largest possible audience, as the efforts of each provider complement each other, giving you the best results from each service.

Providers may rely entirely on human expertise to choose key products to feature, create campaigns, and manage bidding. This approach operates differently from a service like Order Legend, which adds skilled staff on top of a machine learning AI platform and Smart Bidding to scale 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.

Google Shopping Content and Product Type Restrictions

While most retailers can advertise their products on Google Shopping, some inventory and editorial content restrictions apply. Basic editorial standards apply to all ads, including accurate URL display, proper use of letters and symbols, and functional websites.

Prohibited products include potentially harmful items like fireworks, tobacco, and unapproved healthcare supplements. Some products, like alcohol and certain healthcare items, can be advertised but with limitations and adherence to specific country laws and regulations.

For more information on requirements and restrictions, visit the Google Shopping Ads Policy Center.

Keeping your product data feed accurate and valid is crucial, as Google regularly checks the information. Issues may arise due to stock availability, price changes, or alterations to your website and product IDs. A reliable CSS partner can help you anticipate and address these issues.

Success with Google CSS: Business Offering and Partner Strategy

Two main factors contribute to success with Google CSS: the quality of your business offering and your partner strategy. Best practices for CSS align with a solid eCommerce business plan, improving results in other marketing areas, such as Google Shopping and Paid Search advertising and organic Search Engine Optimization.

Ensure that your business meets all advertising requirements and assess your website's quality and performance. An effective existing conversion rate indicates that increasing visitors is likely to result in more sales.

Your products should be competitively priced and accompanied by high-quality images and reviews from previous customers. Stock availability is also crucial, as it can create issues with your data feed.

Another success indicator is sufficient consumer demand for your products, as shown by the search volume for individual items or product categories.

A successful partner strategy depends on your business size. Bigger or strong niche brands benefit from working with multiple CSS partners, while smaller brands with less inventory can focus on a single CSS provider. Choosing a Premium CSS Partner ensures a higher level of customer service and experience, saving time on testing multiple providers.

To drive success with Google CSS, leverage the following four factors:

  1. Your Offering: High-quality website, products, and data feed with a good existing conversion rate
  2. Your Competitiveness: Well-priced products with good reviews and availability
  3. Market Demand: High customer interest and sufficient search volume
  4. CSS Strategy: Selecting the right partners, brand and marketing strategy, and the appropriate commission rates (for managed CSS services)

Summary: The Benefits of Using Google CSS

Now is the perfect time to take advantage of Google Shopping with a CSS partner. With the rapid growth of online retail in the UK and worldwide, an increasing customer base is searching for products. The evolution of Google Shopping ads provides more ways for brands to gain visibility and drive sales.

Larger and more established Premium CSS Partners have the experience, technology, and scale to provide optimization and AI-powered bidding strategies for even the largest businesses. The variations among providers mean that every retailer can find an ideal solution by creating the right Digital Shopping Mix.

To benefit from Google CSS partners, follow these steps:

  1. Ensure your products comply with the Google Ads Shopping Policy
  2. Contact Google Premium CSS partners to learn more about their services
  3. Audit your website to ensure you have a quality offering with competitive products. Your prospective CSS partner may be able to advise you on any obvious issues based on their experience with thousands of retailers
  4. Review the requirements for creating your Product Data feed for uploading by you or your CSS partner, ensuring your internal or external developer resources meet the recommendations from both Google and your CSS partner
  5. Test, refine, and optimize your campaigns to achieve your ideal Digital Shopping Mix

By following these steps and leveraging the expertise of a CSS partner, you can maximize the potential of Google Shopping Ads and drive success for your online retail business.

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Adam Sturrock
Adam Sturrock
Order Legend