23 free tools

Free A/B testing and conversion rate optimization tools

Plan experiments, verify results, optimize assets, build lightweight widgets, and turn test ideas into a prioritized roadmap — no account required.

Build a reliable CRO workflow

How to choose a conversion rate optimization tool

Start with the decision you need to make. Planning tools size and prioritize experiments, optimization tools improve what visitors actually see, and result checkers tell you whether the lift is trustworthy.

Step 1

Plan the experiment

Define the hypothesis, calculate sample size and duration, then rank the test against the rest of your roadmap.

Calculate sample size

Step 2

Improve the experience

Compress oversized images and create focused headlines, banners, or social-proof widgets before you launch a variant.

Optimize page images

Step 3

Validate the result

Check significance, sample-ratio mismatch, conversion rate, and projected revenue impact before calling a winner.

Check significance

Calculators

3 tools

Sample Size Calculator

Find the visitors needed per variant before an experiment can detect the lift you care about.

Calculate sample size

Duration Calculator

Turn required sample size into a run-time estimate using daily traffic and number of variants.

Calculate duration

Significance Calculator

Check completed control and variant counts with a two-sample conversion-rate test.

Check significance

Image Optimization

6 tools

Image Compressor

Compress JPEG, PNG, and WebP assets locally before using them in tests or landing pages.

Compress images

Shopify Image Compressor

Resize product, collection, and hero images before uploading to Shopify themes.

Compress Shopify images

Ecommerce Image Optimizer

Prepare PDP, gallery, collection, and campaign images for faster ecommerce pages.

Optimize ecommerce images

Product Image Compressor

Shrink product photos for product pages, marketplaces, ads, and email blocks.

Compress product images

WebP Converter

Convert JPEG and PNG files to WebP in the browser with optional resizing.

Convert to WebP

Amazon Image Compressor

Resize listing, secondary, A+ content, and ad images before Seller Central upload.

Compress Amazon images

On-page Widgets

2 tools

FOMO Popup Generator

Create social proof notifications with custom messages, timing, preview, and installable code.

Create FOMO popup

Announcement Bar

Build a sticky or inline promo banner with CTA, colors, close control, and generated code.

Create announcement bar

Templates & Resources

4 tools

Test Result Image Generator

Combine control and variant screenshots into a clean result image for reports and social posts.

Generate image

Dynamic UTM Templates

Copy consistent paid-media UTM templates for Google, Meta, TikTok, Pinterest, and Microsoft Ads.

Get UTM templates

Ecommerce CRO Checklist

Work through 100 conversion checks across PDPs, cart, checkout, trust, UX, and analytics.

Open checklist

A/B Test Playbook

Browse ecommerce test ideas by page, impact, effort, and primary learning.

Open playbook

Experiment Planning

8 tools

Hypothesis Generator

Turn an experiment idea into a structured hypothesis, title, and success criteria.

Generate hypothesis

Design Hypothesis Generator

Describe control and variant designs to create a test hypothesis, rationale, and risk checklist.

Create design hypothesis

Headline Generator

Generate headline variants from your product, audience, benefit, and tone.

Generate headlines

MDE Calculator

Translate baseline and target conversion rates into absolute-point and relative lift targets.

Calculate MDE

Conversion Rate Calculator

Calculate conversion rate, remaining conversions to target, and required visitor volume.

Calculate conversion rate

Sample Ratio Mismatch Checker

Detect suspicious traffic allocation drift between intended and observed variant splits.

Check allocation

Revenue Impact Calculator

Estimate incremental monthly revenue from traffic, conversion lift, and average order value.

Estimate revenue impact

Test Prioritization Calculator

Score experiment ideas with impact, confidence, ease, reach, and learning value.

Score a test idea