Mono uses conventional HTTP response codes to indicate the success or failure of an API request. In general: Codes in the 2xx range indicate success. Codes in the 4xx range indicate an error that failed given the information provided (e.g., a required parameter was omitted etc.). Codes in the 5xx range indicate an error with our servers (these are rare).

Error 🚦

What

400 - Bad Request

The request was unacceptable, often due to missing a required parameter.

401 - Unauthorized

No valid API key provided.

402 - Request Failed

The parameters were valid but the request failed.

403 - Forbidden

The API key doesn't have permissions to perform the request.

404 - Not Found

The requested resource doesn't exist.

409 - Conflict

The request conflicts with another request (perhaps due to using the same idempotent key).

429 - Too Many Requests

Too many requests hit the API too quickly. We recommend an exponential backoff of your requests.

500, 502, 503, 504 - Server Errors

Something went wrong on Mono's end. (These are rare.)

200 - OK

Everything worked as expected 😊


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