Text Rendering Is an OS Fingerprint: From the Scaler to the Font List

Every operating system draws text with its own engine: DirectWrite on Windows, Core Text on Apple, FreeType on Linux and Android. Chromium wraps all three behind HarfBuzz and Skia, and the seams show. The set of installed fonts names the OS, the generic and metric-alias fallback chains name it again, and the sub-pixel advance names the scaler underneath. A browser that claims Windows while running on a Linux server leaks all three at once. This walks the stack from how each OS rasterizes a glyph, through how Chromium shapes and measures text internally, to the three font signals a fingerprinter reads, with live numbers from genuine Windows, macOS, and Ubuntu machines.