Opus 4.5 is now 3 months old.

It felt like something of a watershed at the time, and personally I still prefer it over 4.6 in most ways.

Given that we will likely have Opus 4.5-level open-source models in the next few months, I struggle to see how Anthropic in particular is going to keep making money. It’s already the case the four of the top five models on OpenRouter are open source (blue points on the Pareto front of the attached image, from stephenreid.net/llms– not yet Opus 4.5-level, but Sonnet 4.5-level).