On Thursday morning, multiple AI assistants from OpenAI, Anthropic, and xAI experienced service disruptions, preventing some users from logging in, submitting requests, or receiving responses. Affected products included ChatGPT, Claude, Grok, and certain developer tools and API services; the companies subsequently restored their systems one by one.
Many users on social platforms stated that the service outage directly impacted their daily work, affecting scenarios such as writing, information retrieval, programming, and code assistance. This also reflects how generative AI tools are becoming increasingly integrated into office workflows.
OpenAI has the highest number of errors
On the third-party outage tracking platform Downdetector, complaints related to OpenAI peaked at approximately 38,000, significantly higher than those for the other two companies. Based on user-reported issue categories, about 80% were related to ChatGPT, with additional reports concentrated on Codex and the application side.
OpenAI stated at 10:43 AM Eastern Time that it was investigating high error rates affecting ChatGPT and Codex; at 11:17 AM, it reported that mitigation measures had been implemented and that it was continuing to monitor recovery. By approximately 12:55 PM, the related outages appeared to be resolved.
Anthropic experienced two processing outages
Anthropic’s status page showed that Claude Sonnet 5 experienced an increased error rate at 8:37 AM Eastern Time, and was marked as resolved approximately 19 minutes later. A second incident affecting multiple Claude models occurred at 9:26 AM.
Anthropic stated that the team has identified the cause and deployed a fix; the incident ended at 12:16 PM, though the specific cause was not disclosed. A company spokesperson said the infrastructure issue caused partial outages across Claude.ai, Claude Code, Claude Cowork, and the Claude API.
Grok web and API are affected
xAI also confirmed that disruptions occurred across Grok’s web platform, mobile app, in-app services on X, and two API regions in the United States. The company stated at 9:30 AM Eastern Time that it was investigating the issue and working to restore services. Complaints on Downdetector peaked at approximately 1,400 reports.
Based on the disclosure times of each company, ChatGPT and Codex, Claude, and Grok resumed around 12:55 PM, 12:16 PM, and 1:07 PM Eastern Time, respectively.
Additional information: As of now, ChatGPT has over 1 billion weekly active users; Claude has approximately 300 million monthly active users; Grok has approximately 117 million monthly active users as of March 2026.