OpenRouter data shows user spending on OpenAI models last week exceeded spending on Anthropic models for the first time since February 2024, ending Anthropic’s roughly two-and-a-half-year lead. According to ChainCatcher, the shift was driven by Astra, whose model accounted for about 19% of combined OpenAI and Anthropic spending, ahead of Opus 5 at 16%, while GPT-5.6 Sol and Luna each held about 10%.

OpenAI’s rebound had already begun earlier this summer after Terra and Luna were sharply discounted, which lifted usage on OpenRouter and kept some users active even after the promotions ended. After Astra launched, OpenAI’s spending share eventually moved above 50%.

The figures reflect only relative spending on OpenAI and Anthropic within OpenRouter and should not be treated as a direct measure of the broader API market or either company’s total revenue.