10 Best A/B Testing Tools｜Free vs. Paid Comparison and How to Choose
Published:
Last Updated:
Category: SEO & Content
Authors: Shusaku Yosa
Published:
Last Updated:
Category: SEO & Content
Authors: Shusaku Yosa
When you want to improve your website's CVR (conversion rate), A/B testing is an effective approach. However, tools range from free options to high-functionality paid ones, and many people struggle with "which one to choose."
This article organizes and explains everything from the basics of A/B testing tools, to 10 recommended free and paid options, to the points for choosing a tool that fits your company. Note that pricing and features change, so please verify the latest information on each provider's official site before adoption.
A/B testing is a method of preparing two patterns of a web page or LP—A and B—and comparing which performs better on metrics such as conversions or click-through rate. With an A/B testing tool, you can create and serve patterns with no code even without programming knowledge, and automatically determine statistical significance, letting marketing teams run the PDCA cycle quickly on their own initiative.
Many tools can be installed simply by placing one line of dedicated JavaScript tag on your website. If you install it via GTM (Google Tag Manager), you don't even need to edit the HTML directly. For apps, there are also types that embed an SDK.
A free tool that lets you handle the entire testing process—from specifying the target page to setting outcome metrics—with simple operations. Beyond A/B testing, you can also use persona analysis and access-log analysis features for free. It suits companies without a dedicated web department that want to start easily (a paid plan is also available).
A completely free behavior-analysis tool provided by Microsoft. Strictly speaking it isn't a dedicated A/B testing tool, but with heatmaps and session replay you can visualize user behavior, which helps when considering "why" an A/B test produced its result. Realistically, it's used in combination with many A/B testing tools.
The high-functionality tool VWO, described later, offers a free plan and free trial that let you try it at small scale. It's an option when you want to confirm how a full-fledged tool feels without spending money. It's a tool where the flow of first validating for free and then moving to a paid plan as needed is easy to follow.
A standard tool used in over 190 countries worldwide, chosen by many marketers as a migration destination after Google Optimize's discontinuation. It supports A/B testing, multivariate testing, and split URL testing, and has built-in analysis features such as heatmaps and session replay. It also supports official integration with GA4. Pricing is an individual quote based on MTU (monthly tracked users) and the features used.
A pioneer of A/B testing tools and still a top vendor leading the market worldwide. It covers a wide range—from easy visual editing, to engineer-oriented server-side experimentation (Feature Experimentation), to AI personalization. It supports SPAs (dynamic pages) as standard, making it well suited to large sites that want to run advanced, engineering-led experiments.
A tool characterized by AI-powered segmentation and low-load delivery via edge processing. It supports official integration with GA4 and supports SPAs as standard. Note that in January 2026 its integration with VWO was announced, drawing attention in the CRO market. It is also expanding from Europe and North America into the Japanese market.
A Japanese-made LPO and A/B testing tool whose strength is robust Japanese-language support. It supports A/B testing, multivariate testing, and personalization, and also has an integration feature with Microsoft Clarity. It's a strong candidate when you want to pursue full-scale improvement tailored to a domestic company's operational structure.
A Japanese-made site analysis and improvement tool that, in addition to A/B testing, includes heatmap analysis and EFO (entry form optimization). You can check user behavior—clicks, scrolling, mouse movement—on the test page, and its strength is being able to advance analysis and improvement as a set.
A tool that lets you create test patterns easily and validate hypotheses quickly, speeding up your improvement cycle. You can finely group users by attributes and behavioral history, and it supports not only A/B testing but also heatmap analysis and funnel analysis. With a PV-based pricing model starting from around 7,980 yen per month, it can be adopted at relatively low cost.
A Japanese-made tool that clearly positions itself as a Google Optimize alternative. With a simple UI, even beginners can operate it intuitively, and you can start testing right after placing a tag. Its low cost—from the 3,000-yen-per-month range—is appealing, and it also supports integration with Microsoft Clarity. It suits cases where you want to start full-fledged A/B testing affordably first.
The right tool differs depending on whether your purpose is LP CVR improvement, or UI/UX verification and personalization. Check whether the tool has the features you need, such as multivariate testing, server-side testing, or heatmaps. It's also effective to start with hypothesis validation using a free tool, then consider a high-functionality tool when you move into full-scale operation.
Pricing models vary: PV-based pricing tied to monthly PV count, pricing based on monthly tracked users (MTU), individual quotes, and more. Because PV-based pricing can spike sharply as traffic grows, always confirm whether it fits your scale and expected traffic.
If you want to integrate test results with your existing analytics foundation, GA4 integration is important. Official GA4 integration is limited to tools such as VWO, Optimizely, and AB Tasty. Also, to dig into the reasons behind results, it's worth checking whether the tool can integrate with heatmap tools like Microsoft Clarity.
Tag-based tools can cause a flicker phenomenon—where the original design briefly appears on page load due to JavaScript loading—as well as reduced load speed. Because load speed also affects SEO evaluation, whether the tool is designed to handle this appropriately, and whether the support structure is in place, become judgment factors during selection.
A/B testing tools span a wide range, from those you can start with for free and easily, to high-functionality ones supporting server-side experimentation and AI personalization. We recommend first organizing your purpose, budget, and required features, then validating at small scale with a free tool or free trial. From there, compare GA4 integration, impact on load speed, and support structure to choose the tool best suited to your company.
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