# HTTP response codes

# Overview of the User.com API

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HTTP response status codes indicate whether a specific HTTP request has been successfully completed. Responses are grouped in five classes: informational responses, successful responses, redirects, client errors, and servers errors.

All error responses are in the following format, delivered with the corresponding status code:

HTTP (opens new window)

Error Response	Description
400 Bad Request	The request was incorrect, please make sure that passed arguments are matching format in method’s documentation.
401 Unauthorized	Unauthorized. You attempt to authenticate with an invalid username or API key.
403 Forbidden	Forbidden. Your request is not allowed.
404 Not Found	Not Found. You attempt to request a resource which doesn’t exist.
429 Too Many Requests	Too many requests. You have reached a rate limit.
500 Internal Server Error	Internal Server Error. Something unexpected happened on our end. Please try again or contact support.
502 Bad Gateway	The server, while acting as a gateway or proxy, received an invalid response from an inbound server it accessed while
504 Gateway Timeout	The server, while acting as a gateway or proxy, did not receive a timely response from an upstream server it needed to

# More on that to be explained here (opens new window)