Definition

What Is A/B Testing in Web Design?

A controlled experiment where two versions of a webpage element are shown to different user segments simultaneously to determine which performs better against a defined metric.

Related Terms

CRO

Heatmap

Conversion Rate

Landing Page

Analytics

Example

Reload Mode runs an A/B test on a landing page, testing 'Get a Free Audit' vs 'Analyse My Website' as the CTA — the first variant wins with a 22% higher CTR.

Companies that run 5 or more A/B tests per month are twice as likely to see significant conversion rate improvements compared to those running fewer than 2 tests, according to Optimizely's State of Experimentation report.

Synonyms:

Split testing, Multivariate testing

Acronyms:

-

What it applies to

High-traffic pages with clear conversion goals — homepage, landing pages, pricing pages, and key CTAs. A/B testing requires sufficient traffic to reach statistical significance within a reasonable timeframe.

How to run an A/B test

  • Identify the opportunity: Use GA4 and heatmaps to find pages with high traffic and low conversion rates.
  • Form a hypothesis: "Changing [element] from [A] to [B] will increase [metric] because [reason]." Example: "Changing the CTA from 'Contact Us' to 'Get a Free Audit' will increase form clicks by 15% because it communicates value."
  • Create the variant: Design and build the B variant — changing only one element so results are clearly attributable.
  • Split traffic: Use a testing tool (VWO, Optimizely, or Google Optimize) to split visitors 50/50 between control (A) and variant (B).
  • Run until significance: Use a sample size calculator to determine the required number of visitors before starting. Stop only when statistical significance (95% confidence) is reached.
  • Implement the winner and repeat.

In Webflow

Webflow does not have a built-in A/B testing tool. Use VWO or Optimizely — their JavaScript snippets can be added via Google Tag Manager. Alternatively, create two separate Webflow pages and use a server-side or GTM-based URL split to route traffic between them.

A/B Testing: Common Questions Answered

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Answer