The Types of HTTP Status Codes

By understanding these codes and their implications, developers, and webmasters can better manage and troubleshoot their applications, ensuring optimal performance and a seamless user experience. So, let's expand our knowledge and uncover the specifics of each category of HTTP status codes.

Importance of HTTP Status Codes in Rest APIs

HTTP status codes are essential in REST APIs for several reasons. They provide clear error messages, enabling efficient troubleshooting and issue resolution. Standardized codes facilitate documentation and understanding of the API, promoting seamless integration with other systems. By adhering to these codes, compatibility with various clients and frameworks is ensured, enhancing interoperability. Additionally, HTTP status codes contribute to API security by communicating authentication failures and enabling appropriate security measures. In summary, HTTP status codes play a crucial role in creating reliable, user-friendly, and scalable REST APIs.

1xx (Informational) Status Codes

1xx status codes are a category of HTTP status codes used to provide informative responses to the client. They indicate that the server has received the request and is still processing it. These status codes are typically not seen by end-users and are mainly used for communication between the client and the server.

The purpose of 1xx status codes is to provide additional information about the status of the request and inform the client about the progress of the server's processing. They can be used to indicate that the client should continue with its request, that the server is switching protocols, or that the server is still processing the request.

Here are some examples of commonly used 1xx status codes:

1. 100 Continue: This status code indicates that the server has received the initial part of the request, and the client should proceed with sending the remaining part of the request.
2. 101 Switching Protocols: This status code indicates that the server is switching to a different protocol specified in the "Upgrade" header of the client's request. It is typically used in situations where the client requests a protocol upgrade, such as switching from HTTP to WebSocket.
3. 102 Processing: This status code indicates that the server has received and is processing the request, but there is no response available yet. It is often used in scenarios where the server needs more time to generate a response, such as when handling complex computations or lengthy database operations.

These 1xx status codes provide important information during the communication between the client and the server, ensuring a smoother and more efficient interaction.

2xx (Successful) Status Codes

2xx status codes are a category of HTTP status codes that indicate successful responses from the server to the client's request. These status codes indicate that the request was received, understood, and processed successfully.

The purpose of 2xx status codes is to inform the client that their request was successful and that they can proceed accordingly. These status codes indicate that the server successfully processed the request and provided the expected response.

Here are some examples of commonly used 2xx status codes:

1. 200 OK: This status code indicates that the request was successful, and the server has returned the requested resource as a response. It is the most common status code used for successful requests.
2. 201 Created: This status code indicates that the request was successful, and a new resource has been created as a result. It is often used in scenarios where the client submits data that leads to the creation of a new resource on the server.
3. 204 No Content: This status code indicates that the request was successful, but there is no content to send back as a response. It is commonly used in situations where the client's request doesn't require a response body, such as when performing a successful deletion operation.

These 2xx status codes play a crucial role in indicating the success of client requests and enable efficient communication between the client and the server. By receiving these codes, the client can determine the outcome of their request and proceed accordingly.

HTTP Response Example

Once you're satisfied with your request's configuration, you may send your request to the server by pressing the Send button. The Send button is located at the left side of the URL text box.

Screenshot of Martini showing HTTP client request

Normally, the server's response will soon appear in the Response panel.

The response is the server's answer to your request. An HTTP response contains a status code, a status message, headers, and optionally, cookies and a body. The HTTP Client displays all of this data in the Response panel.

In this case, we can see the status code “200” once we received the response.

Screenshot of Martini showing HTTP client response

Additionally, the HTTP Client also displays the time it took to execute the request and the size of the response. If you hover over the duration or size of the request, more information will appear.

In the Response panel's Body tab, you have the option to preview or download the response, as well as set the response's content type so that the text area renders it with proper syntax highlighting.

3xx (Redirection) Status Codes 

3xx status codes are a category of HTTP status codes that indicate redirection. These status codes inform the client that the requested resource is located elsewhere and provide instructions on how to reach it. The purpose of 3xx status codes is to handle situations where a requested resource has been moved, temporarily or permanently, to a different location.

Here are some examples of commonly used 3xx status codes:

1. 301 Moved Permanently: This status code indicates that the requested resource has been permanently moved to a new location. The client should update its bookmarks or references to the old URL and use the new URL for future requests.
2. 302 Found: This status code indicates that the requested resource has been temporarily moved to a different location. The client should continue to use the original URL for future requests, as the redirection may be temporary.
3. 304 Not Modified: This status code is typically used with conditional GET requests. It indicates that the requested resource has not been modified since the client's last request. Instead of returning the resource again, the server instructs the client to use its cached version, reducing unnecessary data transfer.

These 3xx status codes play a crucial role in managing resource location changes and ensuring that clients can reach the correct resources even if they have been moved. By receiving these codes, the client can follow the redirection instructions and access the desired resource effectively.

4xx (Client Error) Status Codes 

4xx status codes are a category of HTTP status codes that indicate client errors. The server sends these codes to inform the client that the request cannot be fulfilled due to an error on the client's side. The purpose of 4xx status codes is to provide specific information about the nature of the client error, allowing the client to understand and potentially resolve the issue.

Here are some examples of commonly used 4xx status codes:

1. 400 Bad Request: This status code indicates that the server cannot process the client's request due to a malformed syntax or invalid parameters. It typically occurs when the server is unable to understand the request.
2. 401 Unauthorized: This status code indicates that the client must authenticate itself before accessing the requested resource. It is commonly used when the client lacks valid authentication credentials or has provided invalid credentials.
3. 404 Not Found: This status code indicates that the server could not find the requested resource. It is commonly used when the client requests a URL that does not exist or has been removed. The 404 error is a well-known indication that the requested page is unavailable.

These 4xx status codes help in troubleshooting client-side errors and providing meaningful feedback to the client about the nature of the issue. By receiving these codes, the client can identify and rectify the error, enabling a more efficient interaction with the server.

5xx (Server Error) Status Codes 

5xx status codes are a category of HTTP status codes that indicate server errors. The server sends these codes to inform the client that the requested resource cannot be accessed due to an error on the server's side. The purpose of 5xx status codes is to notify the client about the server's inability to fulfill the request and provide information about the nature of the error.

Here are some examples of commonly used 5xx status codes:

1. 500 Internal Server Error: This status code indicates that an unexpected condition occurred on the server, resulting in the inability to fulfill the client's request. It is a generic error message that does not provide specific details about the exact nature of the problem.
2. 503 Service Unavailable: This status code indicates that the server is temporarily unable to handle the request due to maintenance or overload. It is commonly used when the server is undergoing maintenance or experiencing excessive traffic and cannot process the request at the moment.

3. 504 Gateway Timeout: This status code indicates that the server acting as a gateway or proxy did not receive a timely response from an upstream server while attempting to fulfill the request. It typically occurs when there is a communication issue between servers.

These 5xx status codes indicate issues on the server side that are preventing the client from accessing the requested resource. By receiving these codes, the client can understand that the problem lies with the server and take appropriate action, such as retrying the request later or contacting the server administrator for resolution.

Take Advantage of HTTP Status Codes

HTTP status codes are essential in web development and API communication. They provide valuable insights into the success or failure of a request, aiding in troubleshooting and enhancing the user experience. By understanding and leveraging these codes effectively, developers can build reliable applications and ensure seamless interactions between clients and servers.