The best A/B testing tool depends on your traffic and your team. Optimizely and Kameleoon suit larger companies running experiments across sites and apps, VWO and AB Tasty suit marketing teams that want testing plus visitor insights, Convert suits privacy-minded businesses, Statsig and PostHog suit product teams, and Unbounce Smart Traffic suits small businesses that live on landing pages.
Every website is full of guesses. Is the headline right? Should the button say "Book a call" or "Get started"? Does the long page beat the short one? A/B testing replaces those guesses with evidence by showing different versions to different visitors and measuring which one gets more people to act.
Google Optimize used to be the free starting point for small businesses, but Google retired it in 2023, so plenty of people are looking for a replacement. The tools below are well known and widely used. I've focused on what each one is known for, so shortlist two and run the same simple test in both, such as a new headline on your best landing page.
What should you look for in an A/B testing tool?
- Visual editor. A point-and-click editor lets marketers change headlines, images and buttons without waiting for a developer.
- Reliable statistics. Look for clear reporting that tells you when a result is trustworthy, not just which version is ahead today.
- Speed and flicker. A good tool loads quickly and avoids showing the original page for a split second before the test version.
- Targeting. Check you can test on specific pages, devices or audiences, such as new visitors or people from an ad campaign.
- Integrations. It should connect to your analytics, so you can see how each version affects sales and sign-ups.
- Privacy. Make sure it handles cookies and consent in a way that fits UK and EU rules.
A/B testing tools compared
| Tool | Best for | Stand-out feature |
|---|---|---|
| Optimizely | Larger companies | Web and feature experimentation |
| VWO | Marketing teams | Testing plus heatmaps and recordings |
| AB Tasty | Testing and personalisation | Experiments plus personalised content |
| Convert | Privacy-minded businesses | Privacy-focused testing |
| Kameleoon | Teams across marketing and product | AI-driven personalisation |
| Statsig | Product teams | Feature flags with experiments |
| PostHog | Startups and product teams | Analytics, replays and tests together |
| Unbounce Smart Traffic | Landing page owners | AI sends visitors to the best variant |
Plans and features change often, so check each vendor's current plans before you commit.
The best A/B testing tools for business
1. Optimizely
Optimizely is one of the best-known names in experimentation. It covers website testing, personalisation and feature experiments for apps and products, and it's built for teams that test constantly.
Who it suits: established businesses with steady traffic and a team that wants to run many tests at once.
What stands out: depth. It handles complex experiments, audiences and testing inside products as well as on marketing pages.
Watch out for: it's an enterprise platform, so a small business running the odd test may find it more than it needs.
2. VWO
VWO combines A/B testing with tools that show what visitors do, including heatmaps, session recordings and surveys. That makes it easier to find what to test as well as run the test.
Who it suits: marketing teams that want research and testing in one place.
What stands out: the insight tools. Watching how people use a page often gives you better test ideas than guessing.
Watch out for: it covers a lot, so pick the modules you need rather than switching everything on.
3. AB Tasty
AB Tasty is an experimentation and personalisation platform used by retailers and brands. It lets you test page changes and show different content to different audiences.
Who it suits: e-commerce and consumer brands that want to tailor pages to different visitors.
What stands out: the mix of testing and personalisation, with a visual editor for marketers and options for developers.
Watch out for: it's aimed at mid-sized and larger businesses, so very small sites may not get full value from it.
4. Convert
Convert, often called Convert Experiences, is a testing tool known for its focus on privacy and for being friendly to agencies and growing businesses.
Who it suits: businesses and agencies that care about privacy and want a straightforward testing tool.
What stands out: its privacy stance and its flexibility, with both a visual editor and code options.
Watch out for: it's focused on testing, so you'll pair it with other tools for heatmaps or recordings.
5. Kameleoon
Kameleoon covers web experimentation, feature experimentation and personalisation in one platform, and it's known for using AI to target content to visitors.
Who it suits: larger businesses where marketing and product teams both run tests.
What stands out: having marketing tests and product tests on one platform, so everyone works from the same data.
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Watch out for: like Optimizely, it's built for scale, so check it matches the size of your testing plans.
6. Statsig
Statsig is a product experimentation platform. It's known for feature flags, which let you switch features on for some users and measure the impact, alongside product analytics.
Who it suits: software and app businesses that want to test new features before rolling them out.
What stands out: the way it links feature releases to results, so you can see whether a change helped.
Watch out for: it's developer-led, so it's not the tool for a marketer who wants to edit a landing page visually.
7. PostHog
PostHog is an open source product platform that combines analytics, session replay, feature flags and A/B testing. It has a free version that suits small teams getting started.
Who it suits: startups and technical small businesses that want analytics and testing in one tool.
What stands out: the all-in-one approach. You can see how people use your product and test changes without stitching several tools together.
Watch out for: it suits people comfortable with a more technical set-up, and its testing is aimed at products more than marketing pages.
8. Unbounce Smart Traffic
Unbounce is a landing page builder with classic A/B testing built in. Its Smart Traffic feature uses AI to send each visitor to the version most likely to convert for them, rather than splitting traffic evenly.
Who it suits: small businesses that run ads to landing pages and want testing without a separate tool.
What stands out: Smart Traffic, which starts learning from fewer visits than a traditional test usually needs.
Watch out for: it only works on pages built in Unbounce, so it won't test the rest of your website.
How to choose the right A/B testing tool
Start with your traffic. A/B tests need enough visitors to give a clear answer, so if your site is quiet, test big changes on your busiest page rather than small tweaks everywhere. If most of your marketing runs through landing pages, a builder with testing built in, such as Unbounce, may be all you need.
Then think about who will run the tests. Marketers usually want a visual editor, which points to VWO, AB Tasty or Convert. Product teams testing features in an app will feel more at home with Statsig, PostHog or Optimizely. Whichever you pick, write down what you expect to happen before each test, so you learn something even when the result surprises you.
If you're new to testing, start with my guide on how to do A/B testing effectively. My introduction to conversion optimisation explains what to test first, and this roundup of landing page builders for marketers helps if you need pages to test.
Building a tool in this space? Here's how tools get considered for my roundups.
Frequently asked questions
What is the best A/B testing tool?
Optimizely and Kameleoon suit larger companies, VWO and AB Tasty suit marketing teams, Convert suits privacy-minded businesses, and Statsig and PostHog suit product teams.
What replaced Google Optimize?
Google retired Optimize in 2023. Popular replacements include VWO, AB Tasty, Convert and PostHog, and many connect to Google Analytics 4.
How much traffic do I need to A/B test?
There's no single number, but tests need enough visitors and conversions to reach a reliable result. Quieter sites should test bigger changes on their busiest pages.
What should I A/B test first?
Start with the page that matters most to your sales, then test the headline, the main call to action or the offer, as these usually have the biggest effect.
