Provider-to-provider migration guides

Switching AI providers is rarely a find-and-replace job. Endpoints, auth, message formats, streaming, tool/function-calling schemas, token counting, and stop conditions all differ — and the differences hide in details that only surface in production. Each guide below maps one provider's API onto another, field by field, with copy-paste before/after code and a rollout checklist.

Pick your route from the directory. The hard part is almost always whichever side uses Anthropic's Messages API or Gemini's native API; anything that's OpenAI-compatible (DeepSeek, and Gemini's compatibility endpoint) is closer to a config change.