ChatGPT temporarily stopped using UTM parameters

OpenAI's ChatGPT temporarily stopped appending UTM parameters to redirection links from October 8 to October 15, according to Julien Ribourt, senior partner data, AI & agentic at Converteo. UTM parameters are small pieces of code added to URLs to help track where website traffic is coming from.

Impact on website traffic tracking

The absence of UTM parameters caused traffic from ChatGPT to be classified as "direct source" instead of being attributed to ChatGPT. This can make it harder for website publishers to analyze their traffic sources accurately. However, the impact was described as moderate, with traffic from ChatGPT representing only 0.3% to 0.5% of traffic for CAC 40 companies in the most extreme cases.

Possible cause of the issue

Ribourt suggested the issue might have been caused by a regression bug introduced during an update to GPT-6. The fact that the problem was resolved by October 16 indicates that OpenAI likely wants to remain visible as a traffic source for websites and applications. Since spring 2025, ChatGPT has included UTM parameters in all links used to visit external sites.

New browser change affects tracking

Links opened from the desktop version of ChatGPT now open in a browser specific to the application, which does not share cookies with the main browser. This change can cause e-commerce merchants to treat visitors from ChatGPT as new users, complicating their tracking efforts. While there are ways to address this, the process is described as tedious and highlights the complexity of these AI platforms.