Can I Use Azure API Management with Anthropic's Claude Model?

Getting it to work is definitely possible, but there are some key differences between Anthropic and OpenAI endpoints. APIM expects certain URL paths and headers, which is often the reason for the "resource not found" error. Make sure that your model is actually deployed on your Foundry instance, as that can easily be overlooked. Some users even opt to manage routing outside of APIM, using a simple proxy or serverless function instead of trying to mimic OpenAI's setup directly.

I encountered similar issues when routing Anthropic through APIM. The problem boils down to Claude's API using a different path and auth header compared to OpenAI. The default OpenAI policy in APIM tries to rewrite the path to `/openai/deployments/...`, which doesn't exist in this case. What worked for us was creating a new API definition in APIM that targets the AI Foundry endpoint directly. You need to set the backend URL to the full inference endpoint (like `https://your-foundry.services.ai.azure.com/models/chat/completions`). Plus, use a set-header policy to send the api-key instead of a bearer token, and make sure to remove any OpenAI-specific path rewrites. The "not supported" error might indicate that APIM is sending OpenAI's version query parameter, so adding a set-query-parameter policy to eliminate that can help.

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