300+ models. Provider fallback. Prompt caching. Model variants. One integration.   OpenRouter OpenRouter ( https://openrouter.ai/?utm_campaign=Onboarding+Flow+-+v4+April+2026&utm_content=A4+Credits+Explainer&utm_medium=email_action&utm_source=customer.io )   Hi botnews, A paid key gives you the full OpenRouter catalog. 300+ models from 60+ providers, including every frontier model: Claude, GPT, Gemini, Llama, and the rest. Same API, same code, same key. Add credits ( https://openrouter.ai/credits?utm_source=email&utm_medium=lifecycle&utm_campaign=onboarding_v2&utm_content=a4_model_diversity&utm_campaign=Onboarding+Flow+-+v4+April+2026&utm_content=A4+Credits+Explainer&utm_medium=email_action&utm_source=customer.io )   WHAT SHIPS WITH A PAID KEY Provider fallback. When a provider goes down, your request re-routes to another provider serving the same model. No retry logic on your end, no downtime for your users. Prompt caching. Repeated context gets cached on supported models. Cut