a Windows browser window with no frame at all covers the screen, as only fullscreen does
Under a Windows claim, outer is larger than inner (a frame), or outer equals inner and the window covers the whole screen from its origin (fullscreen). N/A off Windows and when the window reports a zero size (severity: warn).
What a detector infers
On Windows every top-level window carries invisible resize borders — about 8 px at the left, right and bottom — and outerWidth/outerHeight include them, even maximized (a maximized Chrome on a 1920-wide screen reports outerWidth 1936 at screenX −8). Add the tab strip and toolbar and every windowed desktop browser reports outer larger than inner; measured on real windows, Chrome 153 by 16 × 95 px, Edge 153 by 24 × 92, Brave 153 by 4 × 8.
The one state with no frame is fullscreen, and a fullscreen window covers its monitor from its origin. So a window whose outer size equals its inner size in both dimensions while it is smaller than the screen, or placed away from the screen's origin, is not a window a desktop browser draws: it is a headless browser whose window position and screen were written by a persona.
How to resolve it
Run the browser headed with a real window, or make a headless persona describe the window it actually has: a frameless window must be the size of the screen at its origin.
Read in the wild by
Camoufox (measured)
Measured while establishing ground truth for this row, on a production scraping stack's stock launch configuration (headless, geoip, Windows fingerprint). The window reported no frame at all while sitting part-way across a larger screen.
Camoufox 153.2-based fork, headless: outer 1976×1109 = inner 1976×1109 at screen offset (1012, 164); a second launch: 2215×1228 at (102, 65) on a 2560×1440 screen. Headed Camoufox on the same machine has a frame.
camoufox.comEvery attribution traces to a published artifact. See the sources and their limits.
Nearby checks in Screen & display
- screen.colorDepth decomposes into the CSS color media feature
color-depth-vs-media-colorscreen.colorDepth and the CSS color media feature describe one display in two different units: total bits per pixel, and bits per colour… - the reported colour gamut is carryable by the reported colour depth
colour-gamut-vs-colour-depthscreen.colorDepth and the colour-gamut media query are two readings of one panel, and a measured sweep of a deployed identity matcher found… - screen has an OS chrome inset (avail < screen on either axis)
taskbar-presentscreen.availWidth/availHeight describe the area left over after the OS reserves space for its own chrome — a Windows taskbar, a macOS dock… - the outer window fits within the screen
window-boundsThe check asserts only the zoom-invariant bound: window.outerWidth/outerHeight must be non-zero and must fit within the screen. - a non-touch desktop has a fine pointer + hover
pointer-hover-desktopThis check applies only when the UA identifies a desktop platform (Windows, Macintosh, Mac OS X, X11, Linux, CrOS, and not Android/Mobile)… - maxTouchPoints coheres with pointer media
touch-pointer-coherenceA one-directional coherence test: if navigator.maxTouchPoints is greater than zero, matchMedia("(any-pointer: coarse)") is expected to… - a Chrome or Firefox engine claiming macOS reports no touch points
touch-points-vs-claimed-macosNeither Chrome nor Firefox has a source for touch points on macOS. - screen dimensions resolve via native prototype getters
screen-descriptorsFor width, height, availWidth, availHeight, colorDepth and pixelDepth this asks two questions: does the screen instance carry an own…
Clearcote is a browser built for fingerprint coherence
It is a Chromium fork, maintained by the same people who wrote this reference. It ships as a compiled browser rather than as a stealth script injected into someone else's — which is a description of how it is built, and is not an argument about how it behaves on this check.
This audit takes no position on how Clearcote scores on Screen & display checks, on this one, or anywhere else. It has no baseline corpus of other people's fingerprints to rank you against and no vendor scoreboard — nearly every check is self-referential, asking one browser the same question through two independent APIs and reporting whether both answers can be true at once. It runs identically on any browser, including ours. Run it on yours and read the result yourself.
See the other checks in Screen & display — the family frameless-window-vs-fullscreen belongs to.