Substack now lets you check if a post was written by AI

Substack is giving readers a way to check whether the post they’re reading was written by a human or by a chatbot. The company has partnered with AI-detection firm Pangram to introduce new tools that will let users scan posts, notes, and replies for AI-generated text. CEO Chris Best introduced the features in a post titled “Against Claudefishing,” his term for content that leans on AI while presenting itself as human work.

How the scanning tool works

Scans run on any text longer than one hundred words that is published from July 21 onward, and the result is visible only to the person who requests it. Best says Pangram is not perfect, but points to independent evaluations that credit it with a high degree of accuracy. The feature is live on web and iOS, with an Android version coming later.

Substack’s AI-detection feature arrives at a time when the problem it targets is spreading fast across social platforms. Best cites a recent Pangram estimate that as much as forty percent of posts on some platforms are now fully AI-generated.

Writers can run the same scan before they publish

Readers are not the only ones getting new controls. Substack is adding a “How I make this” statement that lets writers describe their process and set expectations up front. Writers also get the option to run Pangram on their drafts before publishing, and they can report and remove scans of their published work that they believe are mistaken. Best says future additions could include AI preferences inside Reply Rules and reader-side controls for what gets recommended.

For readers, this is a rare transparency feature that hands them a real button to spot AI slop. Substack is not alone in trying to solve this issue. LinkedIn has started reducing the reach of AI-generated posts and comments, and Meta is quietly testing its own AI detection tool, though it has yet to go live. Whether any of these tools can keep pace with the models they’re built to catch remains to be seen.