The OpenType Sanitizer (OTS) parses and serializes OpenType files (OTF, TTF) and WOFF and WOFF2 font files, validating them and sanitizing them as it goes.

The C library is integrated into Chromium and Firefox, and also simple command line tools to check files offline in a terminal.

The CSS font-face property is great for web typography. Having to use images in order to get the correct typeface is a great sadness; one should be able to use vectors.

However, on many platforms the system-level TrueType font renderers have never been part of the attack surface before, and putting them on the front line is a scary proposition... Especially on platforms like Windows, where it's a closed-source blob running with high privilege.

Instructions below are for building standalone OTS utilities, if you want to use OTS as a library then the recommended way is to copy the source code and integrate it into your existing build system. Our build system does not build a shared library intentionally.

Build OTS:

$ meson setup build
$ meson compile -C build

Run ots-sanitize, for example:

$ ./build/ots-sanitize path/to/font/file

Run the tests (if you wish):

$ meson test -C build

See docs

Thanks to Alex Russell for the original idea.