A valid Levanto API key is always required for decision calls. Every POST to /decide and /decide/batch must carry a key; requests without one are rejected with HTTP 401.
Sending the key
Send the key in the Authorization header:
Keys look like lv_live_.... If you don’t have one yet, create it in the dashboard under Intelligence → API Keys.
Only /decide and /decide/batch require a key. GET /ready does not — use it to check model readiness before you have a key.
Error responses
Handling keys safely
Never hardcode, log, echo, or commit your API key. Read it from an environment variable (for example SAGE_API_KEY) and pass it only in the request header.
See Errors for the full status code and error body reference.