Privacy policy

Effective Viewport runs in your browser. This page explains what leaves your machine and what does not.

URLs you preview

When you type a URL into a preview field, it loads directly in iframes in your browser. We do not receive that URL on our servers — there is no server-side fetch or proxy. The URL may appear in your address bar so you can bookmark or share the view.

Site analytics

The site uses a lightweight, privacy-friendly analytics script for aggregate traffic, such as page views. It is separate from preview loading and does not receive the URLs you type into preview fields.

Contact

Questions about this policy: hello@petrvocelka.com.

For years, these numbers were a mystery for developers, designers, and testers. We parroted screen sizes from spec sheets while users were experiencing something completely different in the browser — and nobody had those viewports in one place.

I measure those scenarios on real hardware and simulators and publish them here — viewports you can copy into DevTools, use in Figma, and test automation. The dataset keeps growing and updates when OS or browser UI changes.

Load a URL in the preview, browse the catalog, or share it if the tool helped you.