Claude Code API Gateways on Windows: Verify Base URL and Authentication Before Debugging Models

Many Claude Code gateway failures arise when the correct host or authentication header is not utilized. This guide provides a step-by-step approach for Windows users to diagnose and correct these issues. First, verify the gateway protocol and select the appropriate credential variable. Test the connection in a PowerShell session before making the configuration permanent.

The three essential values that must align are the Base URL, Credential type, and Protocol and path. Derived Base URLs should not be taken from dashboard login URLs. Credential types vary by service documentation, with Bearer tokens and x-api-key flows being common. The Claude Code format is typically exposed under /v1/messages, and incompatible services should not be integrated.

The testing process involves using temporary variables in a PowerShell session to prevent issues if an experiment fails. The gateway token must be entered and replaced with the service's actual values. A visible environment variable does not confirm the gateway accepted the request; a test message and status output should be run to verify.

After confirming the route, launch the CLI from the same PowerShell window to ensure proper process inheritance. If a 401 Unauthorized error occurs, double-check the credential type and ensure it matches the current gateway. Network reachability does not guarantee the endpoint supports the Anthropic Messages format; validate the response format and path before persisting the configuration.

The guide emphasizes the importance of persisting changes only after successful temporary testing and storing credentials securely in user-level settings files, rather than project files or public repositories.