AI tools can identify the writing of almost anyone with a sizable online presence, rendering much online anonymity impossible. The tech writer Kelsey Piper had Claude Opus 4.7 read unpublished 150-word snippets of her writing; it successfully named her as the author each time. Semafor’s Tom Chivers replicated the finding with a segment of his 2019 book. Other models were less successful, and Claude could not identify people who lacked published real-name writing, but that may change soon. “If you leave a detailed anonymous review on Glassdoor after leaving your job,” Piper argued, soon companies will be able “to paste that text into an AI and learn exactly who wrote it… your anonymity isn’t long for the world.”