Free tool
Animation Performance Checker
Find out why a page stutters on phones before the client does: heavy animation libraries, transitions that animate layout, too many Lotties and videos, backdrop filters, scroll listeners and missing reduced-motion support.
Page address
Why it matters
Smooth on your MacBook is not smooth on their phone.
Reads the CSS, not just the page
The site stylesheet is fetched and scanned for transitions on width, height, top and margin, for transition: all, will-change overuse and backdrop-filter, the usual causes of dropped frames.
Weighs the libraries
GSAP and each plugin, Lenis, three.js, Lottie, Swiper and more are detected with their approximate size, so you know what the page pays for before the first frame.
Fixes for Webflow
Every finding comes with the change to make in the Style panel, the Interactions panel or your custom code, ordered by how much it will help.