Lightweight A/B Testing Software

Run performance-safe A/B tests without the bloat. Stellar uses a 5.4KB async script so you can experiment without sacrificing page speed, user experience, or Core Web Vitals.

đź’ł No credit card required
⚡️ Lightest in the market at 5.4kb

See how Stellar compares on script size

Many A/B testing tools add tens or hundreds of kilobytes to every page load. Stellar stays lean so your site speed does not become the hidden variable in every test.

Stellar (0ms)
VWO (100ms)
Optimizely (150ms)
ABlyft (180ms)
Convert (200ms)

At just 5.4KB and served on a CDN, Stellar's pure JS script is 25x smaller than competitors like VWO or AB Tasty. With minimal dependencies and a fixed size regardless of test count, it preserves your website's speed, Core Web Vitals, user experience, and SEO performance.

What to look for in lightweight A/B testing

Script size
5.4KB snippet
Often 40KB–150KB+
Loading behavior
Async by default
Frequently blocks render
Visual editor
Included
Varies by vendor
Free tier
Up to 25k MTU
Often limited

Test without turning speed into a confounding variable

When your testing platform slows pages down, you cannot tell whether a variant lost because of the copy or because of performance. Stellar keeps experiments lightweight so results reflect the change you made.

Focused feature set

Stellar prioritizes experimentation essentials—variants, goals, and analytics—instead of bundling heavy extras that inflate script size.

CDN-delivered snippet

The Stellar snippet and active experiments are served from CDN infrastructure for fast delivery worldwide.

Works on any site

Add one script tag to WordPress, Webflow, Shopify, or custom stacks—no platform-specific plugin required.

Built for performance-conscious teams

5.4KB script—designed to stay out of the critical path
No-code visual editor for fast experiment iteration
Cookieless by default for simpler compliance workflows
Free forever up to 25k monthly tracked users

Pricing

Free

$0 USD/mo.

Up to 25k MTU

Built-in analytics

Visual web editor

Custom CSS & JS editor

AI editor assistant

Basic A/B testing

Up to 3 variants per experiment

Up to 2 experiments running simultaneously

14 day free trial

Pro

$99 USD/mo.
billed annually
Everything in Free, plus:

50k MTU included

Then easily scale with +$2/mo for every additional 1k MTU

Unlimited variants

Unlimited concurrent experiments

Advanced targeting rules

Dynamic keyword insertion

AI insights & recommendations

Priority support

Enterprise

Custom
Everything in Pro, plus:

Custom MTU volume

Tailored pricing for high-volume needs

Custom solutions

Integrations support

âś“ Pay Only For What You Use

We dynamically bill in small increments of 1k MTU, so you only pay for what you actually use and never overpay

âś“ Transparent Pricing

No hidden fees, no large fixed blocks. Scale smoothly as your traffic grows with predictable, usage-based billing

âś“ Fair MTU Counting

We only count users who actually see experiments. Multiple experiment views from the same user count as just 1 MTU

Frequently Asked Questions

Want faster tests and faster pages? Try Stellar