What it does
Diffenator 2 compares static and variable TrueType fonts and produces HTML reports of visual and structural changes. The open-source tool is aimed at foundries checking revised font families before release.
Compare a previous build with a new one using diffenator2 diff -fb before.ttf -fa after.ttf -o report. The output combines rendered-word differences with changes in the fonts’ data structures. A proof subcommand creates specimen pages for a family without requiring a second version.
Add project-specific names, abbreviations or feature combinations through a custom wordlist. A plain text file supplies sample text; CSV can also identify script, language and OpenType features. Default wordlists cannot guarantee that every unusual combination or optional feature remains correct.
Variable-font comparisons use named instances by default. The styles option can instead select masters or combinations of minimum, default and maximum axis values. COLR v1 fonts are supported, and browser images can be generated through Selenium. The comparison scope is static and variable TTF, so other release formats need a separate check.
Strengths
- Rendered-word differences appear alongside structural font-data changes.
- Custom wordlists can target project-specific text and OpenType features.
- Variable fonts can be compared at instances, masters or axis combinations.
Watch out for
- The current comparison scope is TTF.
- Default wordlists do not cover every name, abbreviation or optional feature.
Best for
- Foundries checking font revisions
- Teams reviewing regressions in variable-font releases
Sources
- Diffenator 2 README (Oct 27, 2026)
- Diffenator 2 Apache License (Oct 27, 2026)