One API Key Across OpenAI, Claude and Gemini: Chatbot Fallback Options for SaaS Apps

Short summary

The author recommends using a chatbot gateway that exposes one API and one key across OpenAI, Anthropic, and Google, while keeping fallback routing logic in your own application code. The real cost of multi-provider setups isn't auth but response shape mismatches that break eval harnesses, cost dashboards, and retry logic. Key rules: never fail over after streaming tokens to the user, and always record which model answered on the conversation row.

• •Use a gateway for unified API shape but keep fallback ladder logic in your own testable code
• •Response shape mismatches across providers are the real pain point, not authentication
• •Never fail over mid-stream; buffer the first chunk before committing to a model

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