Can someone help me understand why OpenAI, Anthropic & other proprietary models would want to make their offerings available on OpenRouter?
It seems strategically not in their interest.
They already sell API access to the model on Google/Microsoft/Amazon cloud. OpenRouter is the same deal. Note that the labs are not giving out model weights to OpenRouter. They are just selling tokens.
When the market settles down, most of the money is going to be in bulk inference, for batch jobs. In 5 years everyone's laptop will be able to run Qwen 3.8 27B for coding tasks, but businesses will still need to run inference 24/7. Very few people will still need SOTA models once you can run an Opus 4.6 class model on your laptop.
They get paid the same either way, Openrouter takes their cut and passes it onto the consumer. And anyone with an Openrouter account has already escaped from their proprietary moat. So for those who have expressed a clear preference for provider-agnostic model infrastructure, do you want to just wall yourself away from them forever?
And per the rankings [0] 18.2% of the tokens sold through went to OpenAI [1]. 3.8% for Anthropic though. Google's up there at 23.4% primarily because GCP/Vertex/whatever they're offering is a billing nightmare and the only way to set a hard cap and sure you won't wake up the next day with a $10k bill is via OR.
[0] https://openrouter.ai/rankings#market-share
[1] Although gpt-oss 20b and 120b are indexed as 'openai' because they're the creator even though they don't serve gpt-oss via openrouter. But neither are in the top 20 of models this month, while Luna and Sol are.