Article URL: https://www.mixfont.com/experiments/decoy-font Comments URL: https://news.ycombinator.com/item?id=48936584 Points: 213 # Comments: 71

A TTF font that hides what you're typing from AI. Type a message where each letter contains a decoy. Decoy Font is free to use in personal, commercial, and client projects. Its letterforms are derived from DejaVu Sans Mono; see the full font license for terms. Decoy font is a font that prints a decoy for every letter, making it more difficult for AI to read what you type. The font works by using separate spatial frequencies to communicate two different letters in the same space. The foreground contains thin outlines, while the background is a low-frequency mass that is blurred. When overlaid on top of each other, what you see depends on how you look at the letter. If you’re having a hard time seeing the hidden message, move your screen farther away, or try squinting to see it. Most AI systems work by reading the pixels of an image up close. So when this type of image is pasted into an AI model like ChatGPT, even when the text is small, the llm focuses on the foreground text because that is what is most clearly outlined. However, from a slightly zoomed out distance, the text reads the actual hidden message. This simple illusion is enough to trick even more advanced LLMs like GPT Sol and Gemini 3.5 with Thinking: Decoy Font also exists as an actual TTF font file that can be installed and used to write complete text. You can download and install the TTF font file here. The following paragraph is written in Decoy Font - you can actually copy the text and paste it into your own notepad. Funnily enough, when we pass a screenshot of this font into ChatGPT, it fails to read it properly, even though it might really clear and obvious to you. Decoy Font is constructed based on the technique behind hybrid images. This technique has been well studied for many existing optical illusions. One of the most famous is the image of Albert Einstein and Marilyn Monroe mixed together. Decoy Font applies this same idea to typography as a way to protect the words that you are typing from AI or OCR techniques. We've applied this idea of spatial frequencies to create a new font that can used to obscure your writing from AI scrapers.