GoKawiilWhat is Decoy Font?
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.
Decoy font says two different things from up close vs far away
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:
ChatGPT struggles to read the actual hidden message when passed a single image.
Gemini 3.5 with Thinking also fails to read the actual message.
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.
This sentence is written in Decoy Font
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.
ChatGPT fails to read the Decoy Font properly from a screenshot.
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