What browser and screen am I using?

This page shows it at the top. You can also look in the browser itself: in Chrome and Edge open the menu and choose Help, then About. In Firefox open the menu, then Help, then About Firefox. In Safari choose Safari, then About Safari.

Screen resolution is the whole display. Window size, also called the viewport, is the part of the browser that shows the page, without the tabs, address bar and toolbars. A website lays itself out for the window, so for a layout bug the window size matters most.

Browsers measure in CSS pixels, and most modern screens fit two or more device pixels into each one. The pixel ratio says how many. Multiply the CSS size by it to get the device pixels, which is the number shown first. Display scaling in your system settings and the browser’s zoom both change the ratio, so the result can differ from the panel’s own resolution.

A user agent is a line of text your browser sends with every request to say what it is, such as the browser, its version and the system. It is not always exact. Browsers now freeze parts of it on purpose, so every Mac reports an old macOS version, 10.15, and Windows 11 reports itself as Windows 10. Chrome and Edge tell the real values another way, which this page uses where it can.

No. Everything is read and shown by your own browser. Nothing on this page is sent to Faylee or anyone else, and nothing is stored. We only count how often the page is visited and its buttons are used, never what it shows.

Many bugs only happen in one browser, one version, one system or one window size. Knowing yours lets a developer reproduce the bug on the same setup instead of guessing, which is often the difference between a quick fix and “works on my machine”.

Yes. The page works in any modern browser, on a computer, phone or tablet. Safari and Firefox share less about themselves than Chrome and Edge, so the exact macOS or Windows version may not show there.