Specimen
A specimen sheet is a typeface's honest self-portrait: every size, every glyph, every feature, with nothing chosen to flatter. This one is generated from the files the site actually ships.
Nine faces, each rendered from the file this site ships. The glyph grid below is the real character set of the selected binary, and a feature toggle only appears when that file genuinely carries the feature.
Source Serif 4 publishes wght 200–900.
waterfall — 12 to 240
one paragraph, three optical sizes, one size
opsz 8
The compositor set the page by hand, and the page held its shape for four hundred years. Every decision it recorded — the measure, the leading, the size of the capitals — is still a decision somebody has to make today, usually in a hurry and usually without noticing.
opsz 34
The compositor set the page by hand, and the page held its shape for four hundred years. Every decision it recorded — the measure, the leading, the size of the capitals — is still a decision somebody has to make today, usually in a hurry and usually without noticing.
opsz 60
The compositor set the page by hand, and the page held its shape for four hundred years. Every decision it recorded — the measure, the leading, the size of the capitals — is still a decision somebody has to make today, usually in a hurry and usually without noticing.
glyph grid342 encoded characters · 734 glyphs in file
The file carries more glyphs than encoded characters because small capitals, oldstyle figures and stylistic alternates have no codepoint of their own — they are reached through the features above, which is why a subsetter that drops them leaves no visible trace.
Why this sheet is generated, not written
Every number on this page — the axis ranges, the glyph counts, the list of OpenType features, the character grid — is read out of the woff2 binaries at build time by a script in this repository. None of it is typed by hand from a foundry’s documentation, and that is not fussiness. Published axis ranges are wrong often enough that four of the nine faces here disagreed with their own notes: JetBrains Mono stops at weight 800 rather than 900, Bodoni Moda has no weight below 400, Bricolage Grotesque’s width axis only narrows, and Inter’s optical size range is a narrow 14 to 32.
A slider wired past a font’s real limit does not throw an error. The browser clamps it silently, so the control appears to work while doing nothing across part of its travel, and the reader concludes the site is broken without being able to say where. It is the single most likely bug in a project like this one, and the only reliable defence is to never let a human write the number down.
The pangram, and why it is here
The quick brown fox jumps over the lazy dog. This is the one place on the site where that sentence earns its keep, because a pangram is a specimen tool rather than a piece of writing: it exists to put every letter of the alphabet in front of you in one line so you can check the fit of the whole set at once. Used anywhere else it is filler, which is why it appears on this page and no other.
A pangram is a weak test, though, and worth knowing the limits of. It shows you every letter once but almost no letter pairs, and spacing problems live in the pairs. If you are judging a text face, set a real paragraph of the actual copy at the actual size, which is what the optical size comparison above does. The alphabet tells you what the letters look like. Only prose tells you what reading them is like.
What the glyph count is telling you
Each face reports more glyphs in the file than encoded characters in the grid, and the gap is where the craft is hiding. Small capitals, oldstyle figures, fractions and stylistic alternates are drawings with no codepoint of their own — nothing in Unicode points at them, and they are reachable only through the OpenType features listed above. Source Serif 4 ships 734 glyphs to serve 343 characters. The surplus is small caps, figure sets and the machinery that switches between them.
This is also why subsetting a font by character range quietly destroys it. Strip to the Latin range and every unencoded glyph goes with the ones you asked to lose, so the feature tables survive pointing at drawings that are no longer there. The build for this site hit exactly that: the first font pipeline produced files where not one of the nine faces had small capitals left, and the page about small capitals would have been demonstrating a browser forgery while claiming to show the real thing.
Read the file, not the documentation. The font is the only source that cannot be out of date.