In what cases is the 400 Bad Request code returned? Provide examples for our API.

The 400 Bad Request response code is returned when the client's request is incorrect or cannot be processed due to errors in syntax or logic.

Examples for our API:

• Missing required parameters in the request body or URL.
• Incorrect data format, such as a string instead of a number, invalid JSON.
• Validation violations, such as a string length exceeding the allowed limit.
• Sending unsupported content type.

Example:

If the API expects a POST request with JSON containing the "email" field, and the client sends:

{
  "email": "not-an-email"
}

and email format validation is in place, the server will return 400 with an error message.

Thus, 400 indicates that the client should correct the request before resubmitting.