ttftrim removes glyps from TTF fonts. This is useful if you:

• want to reduce the size of fonts, for example for webfonts;
• don't like some glyps in a font.

This uses the fontforge Python library; usually installing fontforge should install this as well.

Compress and decompress the TTF fonts to WOFF2 with woff2_decompress and woff2_compress from https://github.com/google/woff2 – fontforge includes WOFF2 compression, but it's not very good (giving filesizes more than two times larger).

Usage: ttftrim input-file output-file [corpus-path]

After starting it will load a list of glyphs in $EDITOR; remove the lines you don't want, save, and exit. If corpus is given then it will automatically comment out the glyphs not found in the corpus text:

% ttftrim original.ttf out.ttf ~/code/arp242.net/_site

This can be a file or directory tree.

For example before reducing the glyphs to those used only on my site:

total 144K
-rw-r--r-- 1 martin martin 44K Nov 30 16:36 libre-baskerville-bold.woff2
-rw-r--r-- 1 martin martin 53K Nov 30 16:36 libre-baskerville-italic.woff2
-rw-r--r-- 1 martin martin 43K Nov 30 16:36 libre-baskerville.woff2

And after:

total 52K
-rw-r--r-- 1 martin martin 16K May 16 19:36 libre-baskerville-bold.woff2
-rw-r--r-- 1 martin martin 19K May 16 19:36 libre-baskerville-italic.woff2
-rw-r--r-- 1 martin martin 16K May 16 19:25 libre-baskerville.woff2

Note: this tool hasn't been tested too extensively. In fact, it's tested with just the one font I use on my website (Libre Baskerville) 🙃

Note 2: it doesn't modify lookup tables at the moment, so if you remove a glyph mentioned in a loopup table you'll get a validation error.