OpenAI-Compatible API Migration Checklist

Compatibility is more than the URL

Many gateways accept an OpenAI-shaped request, but applications often rely on details beyond the basic message format. Inventory the endpoints, streaming behavior, tool calls, structured outputs, image inputs, error handling, and model names your product uses before changing traffic.

Pre-migration checklist

Verify the following in a development environment before the first production test:

• Base URL and authentication header work with your current SDK.
• Required model slugs and context limits are available.
• Streaming events are parsed correctly.
• Tool-call and structured-output payloads match application expectations.
• Timeouts, retries, and error bodies are handled explicitly.
• Request IDs and usage fields reach your observability system.

Roll out with comparable traffic

Start with a small percentage of representative requests and compare success rate, latency, response quality, and cost against the existing path. Keep a quick rollback mechanism while you learn how the new route behaves under real concurrency and long-running streams.

After migration

Update runbooks, rotate unused provider credentials, and document who owns routing policies. Continue monitoring at the feature level so improvements or regressions are visible to the team that owns the user experience.