AI can now identify who you are from your writing style — Claude Opus 4.7 deanonymizes authors in seconds

Anthropic's Claude Opus 4.7 can identify the author of anonymous text by analyzing writing style (word choice, sentence patterns, topics) — a task that three years ago required custom code and weeks of work. A researcher demonstrated this by feeding the AI a paragraph from an unpublished blog post and asking it to guess the writer's identity.

Unlike old deanonymization methods that needed large databases and specialized programming, Opus 4.7 does it conversationally: you simply paste text and ask "who wrote this?" This makes the technique accessible to anyone with an AI subscription, not just researchers with technical skills.

If you write pseudonymously online—on forums, in comments, in published essays—your identity can now be revealed far more easily than before. This affects activists, whistleblowers, journalists protecting sources, and anyone relying on anonymous accounts for candid discussion. Your writing style is essentially a fingerprint that modern AI can read.