Split testing, or A/B testing, is a valuable way for website owners to discover how people interact with their sites and improve the user experience and conversion rates. By comparing a control page against a test group, website testing allows us to analyze the performance impact of changes made and make data-driven decisions to enhance the effectiveness of our websites. This comprehensive guide will delve into the dos and don’ts of A/B testing and explore how it can impact SEO.
Understanding A/B Testing
A/B testing involves changing one or more elements of a webpage and comparing the performance of the original page (variant A) with that of the test page (variant B). This straightforward test allows us to determine which version converts faster. Some everyday use cases for A/B testing include testing call-to-action (CTA) messaging and color changes.
During an A/B test, different versions of a page’s content are served on various URLs, and users are redirected to a specific version based on predetermined test thresholds. This ensures that users have a consistent experience and enables us to measure the effectiveness of the changes made.
The Power of Multivariate Testing
While A/B testing focuses on comparing two versions of a webpage, multivariate testing takes it a step further by simultaneously testing multiple sections on a page. This allows us to identify the most effective combinations of changes and gain granular insights into page optimization opportunities.

For example, multivariate testing can involve combinations of headlines and images or combinations of body text and buttons. Multivariate testing provides a comprehensive understanding of how different elements work together and impact each other by dynamically changing page aspects and directing all users to a single page with variations inserted.
The Impact of A/B Testing and Multivariate Testing on SEO
While conducting tests to understand better user interactions with our websites is beneficial, it is crucial to manage these tests properly to avoid negative impacts on SEO. A poorly executed test can lead to issues such as cloaking, page duplication, and inconsistent redirects, which can harm a website’s rankings in search engine results pages (SERPs).
Cloaking: When test versions significantly differ from what users see, search engines consider it cloaking, which violates Google’s Webmaster Guidelines. Cloaking can result in demotion or removal of a site from organic search rankings.
Page duplication: Duplication problems can happen when search engines can access multiple sets of pages very similar to each other without proper management.
Inconsistent redirects: A/B testing involves serving different URLs based on user and session, which can confuse search engines about the primary page that should be indexed.
To better understand the SEO impact of website testing, let’s explore the recommendations provided by search engines.

Google’s Perspective on Website Testing
Google emphasizes stability and consistency in websites that run tests. They expect the long-term stable situation on a site to align with the content provided to users. If there is a significant disparity between the content shown to Google and what users see, it can be problematic. For example, showing Google a page with extensive textual content while displaying only a few words and a large image to users can cause issues.
Google recommends showing Googlebot (Google’s web crawling bot) the version of a page that the majority of users see. Randomly switching versions makes it difficult for search engines to understand if significant changes are occurring or if it is merely a swapping of two versions. Consistency is critical in ensuring search engines can accurately index the content on a page.
For more information on best practices for website testing, refer to Google’s guidelines.
Bing’s Stance on Website Testing
Bing’s Webmaster team advises serving the control (version A) to Bingbot and other search engines when running human-targeted experiments. They prioritize stability over instability and prefer a well-established version of a site. Bing distinguishes between minor content differences and significant differences when considering cloaking. They also recommend running experiments over weeks, not hours, to fully understand the impact and limit the scope to versions A and B.

Best Practices for SEO-friendly Website Testing
Tests to optimize website performance must follow recommended practices to satisfy search engines. These eight tips will help you perform tests without hurting SEO:
- Serve Primary Content to Google: When making changes to a page, ensure that the primary content you want to rank with is accessible to search engines. Avoid removing key sections of body copy that could impact search engines’ understanding of the page’s overall topic.
- Avoid Distinctly Different Pages: Search engines can detect minor changes between pages for testing purposes, but if the variations differ drastically, they can be flagged as cloaking. The page that search engines access should align with the primary topic of the original page.
- Use the rel=”canonical” Tag: If you create multiple URLs for the same page, include a canonical tag to search for it. Search engines won’t pick up bogus test pages after this.
- Be Cautious with Noindexing or Blocking Test URLs: Noindex tags on duplicate pages are hazardous. Google may index a variation URL if it determines its canonical tag based on other website signals. Blocking test pages in robots.txt may also shroud them from search engines.
- Use 302 Redirects for Split Tests: When running split tests involving redirection, use 302 redirects to signal search engines that the redirect is temporary. This ensures that the original control page remains in the index.
- Retain the Original Page: Preserve link equity by maintaining the existing URL and making content updates as required. If separate URLs are used for variants, update the current page with changes from the new page version or add a 301 redirect to the winning variant page to pass ranking signals and prevent page duplication.
- Run Tests for an Appropriate Duration: Strike a balance between running tests long enough to gather meaningful data and avoiding prolonged impacts on organic search performance. Google suggests running experiments for at least two weeks or until one variant has a 95% probability of beating the baseline.
- Avoid Tests During Significant Site Changes: Running tests during site restructuring or migration can impede search engines’ ability to interpret signals correctly. This can delay the overall transition from one version to another.

FAQ’s
1. What is A/B testing in the context of SEO?
A/B testing in SEO involves comparing two web page versions to see which performs better regarding search engine rankings and user engagement.
2. Why is A/B testing important for SEO success?
If you want to boost your website’s speed, user experience, and search engine rankings, A/B testing is the way to go.
3. What elements of a website can be A/B tested for SEO purposes?
Elements such as headlines, call-to-action buttons, images, layout, and content can be A/B tested to optimize for better SEO performance.
4. How can A/B testing help in improving conversion rates for SEO?
By testing different variations of elements on a web page, you can identify which ones lead to higher conversion rates, ultimately improving your SEO performance.
5. What are some best practices for conducting A/B testing for SEO?
Some best practices include:
- Clearly define your goals.
- Testing one element at a time.
- Ensuring statistical significance.
- Continuously iterating based on the results to improve SEO success.
A/B and multivariate testing are two of the best ways to improve the speed and conversions of your website. But it’s important to keep SEO best practices in mind when doing these tests so that they don’t hurt your search engine results. By following the advice in this guide, you can run tests well while keeping your SEO strong. Remember that the goal is to make the user experience smooth while also making your website work better all the time.