The diagram
Every HTTP response is a decision.
Send a request from the rail, or call this page's live URL with curl, and watch the flowchart decide the status one question at a time.
WebMacha sandbox
Before anything else about the request is considered, the resource looks at it and decides it is malformed. B9 says true, so the machine stops early with 400 Bad Request.
Decision flow
Decision path
Send a request to see its path through the machine.
Request log
No requests yet. Simulated and live requests appear here; select one to replay it.