Knowledge base
Font and webfont guides
Practical material about OpenType, WOFF2, subsetting, CSS, performance and licensing.
OpenType · Webfont
How to check Polish characters in a font
checking ą, ć, ę, ł, ń, ó, ś, ź and ż
OpenType · Webfont
TTF, OTF, WOFF and WOFF2 — key differences
choosing a format for desktop, print and the web
OpenType · Webfont
How to prepare a font for the web
conversion, subsetting, CSS and performance testing
OpenType · Webfont
How to generate correct @font-face rules
WOFF2 sources, weights, styles and paths
OpenType · Webfont
How font-display works
swap, fallback, optional and their UX impact
OpenType · Webfont
How to reduce font file size
WOFF2 compression and removing unused characters
OpenType · Webfont
What is a font subset
safely limiting the glyph set
OpenType · Webfont
How to create a subset from used characters
extracting text and preserving layout features
OpenType · Webfont
How to prepare a Polish font subset
Polish letters, punctuation and quotation marks
OpenType · Webfont
How to check a font license
metadata, the license document and webfont terms
OpenType · Webfont
What does fsType mean in a font
technical embedding flags and their limits
OpenType · Webfont
How to identify a variable font
fvar, STAT and variation axes
OpenType · Webfont
How to use the wght axis
weight ranges and correct CSS
OpenType · Webfont
How to use the wdth axis
font width without synthetic scaling
OpenType · Webfont
How to use font-variation-settings
standard and custom CSS axes
OpenType · Webfont
How to test font ligatures
liga, dlig, clig and shaping comparison
OpenType · Webfont
What is kerning and how to test it
letter pairs, GPOS and text readability
OpenType · Webfont
GPOS and GSUB in plain language
positioning, substitutions and OpenType features
OpenType · Webfont
How to inspect OpenType features
feature tags, scripts and practical previews
OpenType · Webfont
How to check for real small caps
smcp, c2sc and the difference from scaling
OpenType · Webfont
Tabular and proportional figures
tnum, pnum and use in tables
OpenType · Webfont
How to compare two fonts reliably
shared text, optical size and metrics
OpenType · Webfont
How to choose a font for long-form text
readability, rhythm, width and languages
OpenType · Webfont
How to check whether a font is monospaced
glyph metrics and the fixed-pitch declaration
OpenType · Webfont
How to read font metrics
units per em, x-height, cap height and widths
OpenType · Webfont
Ascender, descender and line gap
vertical metrics and line spacing
OpenType · Webfont
How to reduce layout shift when a font loads
fallbacks, size-adjust and metric overrides
OpenType · Webfont
When to preload fonts
resource priority and avoiding excessive preloads
OpenType · Webfont
How unicode-range works in @font-face
splitting fonts by language and character range
OpenType · Webfont
How to test a multilingual font
character coverage, localized forms and shaping
OpenType · Webfont
What are glyphs without Unicode values
alternates, ligatures and the private use area
OpenType · Webfont
How to create a font specimen
alphabets, paragraphs, figures and typographic features
OpenType · Webfont
How to analyze many fonts at once
duplicates, versions and family consistency
OpenType · Webfont
Why a font does not work in the browser
CORS, MIME, paths, format and CSS errors
OpenType · Webfont
Common webfont deployment mistakes
family names, weights, caching and unnecessary files
OpenType · Webfont
Can you convert a purchased font
license scope, modification and publication
OpenType · Webfont
How color fonts work
COLR, CPAL, SVG and bitmap formats
OpenType · Webfont
CFF vs TrueType outlines
outline differences and safe webfont compression
OpenType · Webfont
How to optimize a family with many weights
choosing required styles and variable fonts
OpenType · Webfont
How to store font files safely
backups, licenses, versions and team access