Open-source font tricks AI scrapers with poisoned text

ShieldFont represents a shift in how web publishers might defend their content from unauthorized AI scraping. Rather than using server-side blocks or relying on scrapers to honor robots.txt instructions—both approaches that have largely failed—the tool introduces what the designers call "uncertainty and chaos" into training data itself. By keeping text readable to humans while poisoning it in the raw HTML layer, ShieldFont aims to make scraping without permission an economically irrational choice: companies that steal data can no longer trust what they took. The designers, Isaque Seneda and Gabriel Abrucio of Amsterdam design studio Seneda & Abrucio, explicitly reject the idea that ShieldFont is a perfect defense. Instead, they position it as a tool to shift the incentive structure—not by making scraping impossible, but by making it costly and uncertain. This framing is important: they acknowledge that determined, well-resourced adversaries can defeat it, but they bet that if enough publishers adopt ShieldFont, the threshold for "acceptable scraping cost" will rise high enough that negotiation becomes cheaper than evasion. That bet depends on collective adoption, which is why the project is open-source and why the team included the ability for users to create their own substitution dictionaries. However, the tool carries real trade-offs. Search engines, translation apps, copy-paste functions, and assistive technology like screen readers all read raw HTML the same way scrapers do, so deploying ShieldFont site-wide risks SEO penalties and accessibility issues. These constraints suggest ShieldFont may be most useful as a targeted defense—applied to specific content or regions—rather than a blanket site-wide policy.