Earlier quoted context omitted.
You create an account. Pay money. Get API key. Use APIs.
But if you use any decent amount of tokens, it's probably worth saving the 15% by moving to the provider they're proxying. And if it's not worth it, then are you spending enough where it even effects Openrouter's bottom line? With enough devs playing with hobby projects I'm not doubting it's profitable, only that $7 billion seems way too high.
It also has way better uptime than the underlying platforms, even for proprietary models like Claude. When Claude APIs are having issues, OpenRouter Claude still keeps working because they can route to AWS Bedrock instead of Anthropic etc. This effect is even bigger with open-weight models because they typically have 5-10 providers.