LinkedIn Leads AI-Generated Long-Form Content Across Social Media

A study by AI‑detection startup Pangram examined more than one million posts from LinkedIn, X, Medium, Substack and Reddit. Across all platforms, 13.8% of posts were identified as AI‑generated, but the share rose sharply with length – 25.7% of posts longer than 250 words were fully written by AI.

LinkedIn showed the highest prevalence: 41% of its long‑form posts were completely AI‑generated, and about 30% of its shorter posts also came from AI. On X, roughly one‑quarter of long posts were fully AI‑written and another 23% were AI‑assisted, meaning about half of X’s long content bears an AI imprint. Medium and Substack displayed lower but still notable rates (around one in three Medium pieces and 21.9% of Substack posts involved AI). Reddit’s main posts had only 11.6% AI involvement, and its comments remained overwhelmingly human‑authored (98%).

Pangram offers a Chrome extension that scans these platforms for AI content, priced at $20 per month for automatic detection, with a free tier limited to manual checks. The researchers warn that unchecked AI‑generated content could erode the authenticity of online discourse unless users are made aware of its origins.