Model Routing

OpenRouter separates two choices that are easy to confuse: which model answers and which provider runs it. Its routing guide explains that a request names a model, and when several companies host that model, OpenRouter's provider routing selects among them, by default favoring the cheapest recently reliable host.

The distinction matters when something fails. Provider failover tries another host for the same model and is on by default; a model fallback list, which the developer supplies, tries a different model if the first fails. Developers can therefore decide whether recovery should preserve the selected model or permit a substitute. The guide notes that these mechanisms route around provider failures but cannot route around OpenRouter itself, citing an August 2025 outage that took down the whole service.