A Comprehensive Guide to HTTP Status Codes

HTTP status codes are server responses, initiated when requests are made to browsers. Usually, a code is of 3 digits. Through these digits, a server shows the status of a request. Hence, they are important to know the response of the server and infer whether it is positive or negative in nature. It can imply that the desired result has been generated. Or, it can reveal that an error exists in a specific website or its page. There are 5 main categories to which the status codes belong. These categories are 1xx, 2xx, 3xx, 4xx, as well as 5xx. Some of the common codes in these categories are 404, 402, 200, 401, 302, 301, 200 OK, 500, 502, and others. Depending on the category, the status is reflected. Note that the importance of the series of digits holds relevance not only for users but also for SEO or search engine optimization purposes. 

What is an HTTP Status Code?

An HTTP status code is a response received when a web page is requested. As a link is clicked, a URL is entered, or a search result is obtained, this page is requested from a specific server. In case any error is made or appears while making the request, the code appears. 

• The code hints at the occurrence of the instance. 
• Or, it indicates the ongoing effort of the server to present the desired result.

Why are HTTP Status Codes Important?

HTTP status codes are significant for diagnosing issues on websites. A server not being operative is one of the services. Others can include the unavailability of pages or links being improper. The sooner they are detected, the quicker their resolution will be.

• Post resolving website errors, visitors can receive better experiences.
• The availability of pages can facilitate their ranking in search engines.

What are the Main HTTP Status Code Categories?

There are 5 classes or categories of HTTP status codes. The initial digit signals the status class. Following that, there are particular codes belonging to every class. Usually, a status code comprises a descriptive term such as “Moved Permanently”, “OK”, etc. However, at times, the descriptions for certain servers can be varied.

Code Category	Indication
1xx, informational response	This code shows that the server is continuing to process.
2xx, success	It reflects that the request has been fulfilled.
3xx, redirection	This category code signifies redirection.
4xx, client error	It denotes that the requested resource isn’t allowed or is non-existent.
5xx, server error	The code implies downtime, the presence of a bug, or temporary maintenance.

Note: The Internet Assigned Numbers Authority (IANA) manages the official HTTP status codes list.

What are the Most Common HTTP Status Codes?

There are 15 HTTP status codes that are the most common. They belong to 4 categories, ranging from 2xx, success to 5xx, server error. It is crucial to know the indication produced by each of these to understand the status of the request made.

Code	Indication
200 OK	200 OK is an HTTP status code which signals that a request made on the browser has been successful. Further, it means that a client has received what was needed.
301 Moved Permanently	This code is important for sites that change URLs in relation to SEO or search engine optimization.
302 Found (Moved Temporarily)	It is utilized for redirection on a temporary basis.
304 Not Modified	Such a code reflects that the needed document hasn’t changed. Further, it tells that the document is cached on the client’s computer.
307 Internal Redirect	This is a temporary redirect code.
307 Temporary Redirect	It has been designed to restrict a change to GET from POST.
308 Permanent Redirect	The code can indicate that a change to GET from the POST method has been disallowed.
404 Not Found	It hints that the needed URL has nothing, however, it may have something available afterward.
410 Gone	The 410 HTTP status code means that the page requested is no longer available.
429 Too many requests	This code in the web crawler denotes that the server is preventing overloading by rate-limiting a request.
500 Internal Server Error	It shows that there has been an unexpected occurrence or an error has been encountered.
502 Bad Gateway	When this code is seen, it denotes that the server, functioning as a proxy server or gateway, has obtained an invalid response via another server.
503 Service Unavailable	The code reflects that a server is under maintenance, overloaded, or busy.
504 Gateway Timeout	This status code implies that a server, operative as a proxy, has run out of time while requesting an upstream server’s response.

How Do You Check an HTTP Status Code?

In order to check an HTTP status code, several ways can be implemented. One can depend on these even to check server headers or HTTP headers. These ways can include adding browser plugins, using online or web-based tools, and relying on a web crawler.

Adding Browser Plugins

Browser plugins can enable checking HTTP status codes. These plugins can be added to check for redirects when requests are made via the browser. For Mozilla Firefox, HTTP Header Live is a suitable plugin to use. Ayima Redirect Path is an apt option in the case of Google Chrome.

Utilizing Online Tools

Certain online or web-based tools provide URL checks for server headers as well as HTTP status codes in bulk. Though there are multiple tools one can use, three of these are preferable. 

• http://www.urlitor.com/
• http://tools.seobook.com/server-header-checker/
• https://httpstatus.io/

Using a Web Crawler

Through a web crawler, a number of URLs can be checked. The configuration of several crawlers can be initiated for the extraction of the complete HTTP header. Take into account that the reporting of response codes is undertaken by default. To check an HTTP status code via a web crawler, Screaming Frog can be used.

• This is an industry-leading and trusted crawler.
• It offers advanced reports relating to status codes.

How to Use an HTTP Status Code?

An HTTP status code can be correctly used, depending on its category, i.e., 3xx, 4xx, and 2xx. Take into consideration that each code is available to send across a message. Therefore, its utilization should be in accordance with the same. 

Are HTTP Status Codes Important for SEO?

HTTP status codes are important for the purpose of search engine optimization. They help in assessing whether a specific website is healthy. Among all, a few codes are more crucial in this regard. They put forth the status of the request a user makes. As per the message on the display, one can initiate changes to the website or its pages.

200: Success 

Finding pages that result in the 200 status code is considered positive for SEO. The pages can unfold that servers are completing users’ requests as needed. Further, it hints at the satisfaction of every such user.

503: Service Unavailable

The HTTP status code 503 is a server-related bug. It specifies that a server can’t handle a request on a temporary basis. Its inability can arise as a result of maintenance, issues, or overloading. For SEO, the impact of this error is concerning in case it lasts for a long time.

The code can signify to a search engine that a website is not available or reliable.

Note that its short-term usage can limit the negative impact of search engine optimization.

Thus, crawlers can be indicated about the availability of the site.

Note: Using the Retry-After value can direct crawlers to try the website after some time.

On a Final Note

An HTTP status code, in simple words, is a response from a server. It is received while managing a user’s request on a browser. Each code is crucial to understand the status of this request. Knowing the main categories of these can assist users in identifying whether or not a web page is available, missing, or problematic.