Simon Willison’s Weblog

23rd June 2024 - Link Blog

llama.ttf (via) llama.ttf is "a font file which is also a large language model and an inference engine for that model".

You can see it kick into action at 8m28s in this video, where creator Søren Fuglede Jørgensen types "Once upon a time" followed by dozens of exclamation marks, and those exclamation marks then switch out to render a continuation of the story. But... when they paste the code out of the editor again it shows as the original exclamation marks were preserved - the LLM output was presented only in the way they were rendered.

The key trick here is that the font renderer library HarfBuzz (used by Firefox, Chrome, Android, GNOME and more) added a new WebAssembly extension in version 8.0 last year, which is powerful enough to run a full LLM based on the tinyllama-15M model - which fits in a 60MB font file.

(Here's a related demo from Valdemar Erk showing Tetris running in a WASM font, at 22m56s in this video.)

The source code for llama.ttf is available on GitHub.