Substack has introduced an AI detection feature, developed in partnership with Pangram, that lets readers assess how much of a piece of content was likely written by artificial intelligence. The move reflects growing pressure on publishing platforms to address concerns about undisclosed AI-generated content, and comes alongside a new feature allowing creators to explicitly disclose their use of AI when producing their work. Substack framed the changes around transparency, arguing that "people should know what they're getting."

The detection tool works on text over 100 words published from the launch date onwards, and is available immediately on web and iOS, with Android support expected later. Substack's announcement took a notably combative tone, criticising LinkedIn for hosting AI-generated content and coining the term "Claudefishing" for using AI to fake human connection. However, the company acknowledged that Pangram's detection has limitations, an admission reinforced by separate reporting from The Atlantic questioning the accuracy of AI-detection tools more broadly.