The Auto Router automatically selects the best model for your prompt, powered by the wisdom of the market. It routes you based on what the OpenRouter community collectively spends on for exactly the kind of task your prompt represents. It looks at spend over a trailing 7-day window, so it stays up to date with new model releases automatically.
Your response will be priced at the same rate as the routed model. The cost_tier setting (low, medium, high, xhigh, or max) selects how much you're willing to pay. The default is low, giving you a highly cost-efficient set of models. When selecting models, the auto router respects any guardrails, privacy/ZDR policies, and model restrictions you have in the request or account settings. Multi-turn conversations stick to one model until it is no longer a leading choice for your task.
Learn more in our docs. For another way to route, see Pareto Code.