Dev.to
7/25/2026
Using the OpenAI SDK to Call Claude: Understanding SDK, API, and Model Separation
Original: I Used the OpenAI SDK—and Claude Answered. Here’s Why.
Short summary
The OpenAI Python SDK can call Claude through Anthropic's compatibility endpoint because the SDK, the API contract, and the model are three independent layers. The article walks through a four-layer mental model—application/SDK, API gateway, serving layer, and inference runtime—showing why base_url and model identifier determine what actually runs, not the package name. It also notes this compatibility path is for testing, not recommended for production Claude-first apps.
- •OpenAI SDK can call Claude via Anthropic's compatibility endpoint—SDK, API contract, and model are separate layers
- •Four-layer mental model: application/SDK, API gateway, serving layer, inference runtime
- •Compatibility layer is for testing/comparison, not recommended production path for Claude-first apps
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