TOKENIZER MONO

Summary from the TLDR Design newsletter

Tokenizer Mono is an experimental typeface based on IBM Plex Mono that visualizes how language models split text into tokens, using OpenType features to highlight boundaries directly as someone types without running a tokenizer in JavaScript. Its 28 styles represent different tokenizers from OpenAI, Meta, Google, DeepSeek, and others, combining contextual glyph substitutions with built-in color palettes to approximate token boundaries. Most styles achieve roughly 98% agreement with real tokenizers in testing, demonstrating how advanced font technology can perform surprisingly complex text processing while revealing its limitations around line breaks, uncommon words, and tokenization algorithms.