# API Error Codes

The API returns different error codes using the HTTP status and will also
include some high-level information in the JSON response, including the status
code, a message, and sometimes a more elaborate description.


```json
{
    "code": "validationerror",
    "type": "query",
    "message": "ValidationError: \"size\" must be greater than or equal to 0",
    "errors": [
        {
            "code": "validationerror",
            "title": "Field Validation Error",
            "description": "ValidationError: \"size\" must be greater than or equal to 0",
            "status": 400
        }
    ]
}
```

## Scan API

For scan submissions, there are various reasons why a scan request won't be
accepted and will return an error code. This includes, among others:

* Blacklisted domains and URLs, requested to be blacklisted by their respective owners.
* Spammy submissions of URLs known to be used only for spamming this service.
* Invalid hostnames or invalid protocol schemes (e.g., FTP).
* Missing URL property ... yes, it does happen.
* Contains HTTP basic auth information ... yes, that happens as well.
* Non-resolvable hostnames (A, AAAA, CNAME) which we will not even try to scan.


An error will typically be indicated by the HTTP 400 status code. It might look like this:


```json
{
    "message": "DNS Error - Could not resolve domain",
    "description": "The domain .google.com could not be resolved to a valid IPv4/IPv6 address. We won't try to load it in the browser.",
    "status": 400,
    "errors": [
        {
            "title": "DNS Error - Could not resolve domain",
            "detail": "The domain .google.com could not be resolved to a valid IPv4/IPv6 address. We won't try to load it in the browser.",
            "status": 400
        }
    ]
}
```