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Common HTTP Response Codes Explained

A graphic that says: Common HTTP Response Codes Explained.

Ever landed on a page excited to see the content only to be greeted by an enigmatic “404 Not Found” message? 

Or maybe you’ve been puzzled by seeing “301 Moved Permanently” pop up. If you’ve ever wondered why your favorite pages suddenly become unreachable or why your website’s traffic isn’t performing as expected, understanding HTTP response codes is key.

HTTP response codes are like the secret language of servers, communicating the status of your request to access a webpage. Whether you’re a digital marketer, a website owner, or just curious about the backend of internet browsing, knowing what these codes mean can significantly enhance your SEO strategy.

In this article, we’ll dive into HTTP response codes. From what these codes are and why they’re critical to your SEO checklist.

Key Takeaways

  • HTTP status codes are short messages from a web server that indicate whether your attempt to view a page was successful, redirected, or failed.
  • These codes are critical for SEO as they tell search engines the status of a page, influencing how your site is indexed and ranked.
  • The must-know codes for optimizing your site include “200 OK” for success, “301 Moved Permanently” for effective redirection, “404 Not Found” for missing pages, and “5XX” for server errors.
  • Proper handling of these codes can improve your site’s reliability and usability, directly enhancing your SEO efforts and user experience.

What Are HTTP Status Codes?

A 404 error message on Neil Patel's website.

Source: NP Digital

So, what exactly are HTTP status codes? Think of them as short notes from a website’s server to your browser. Every time you click a link or type a URL, your browser sends out a request to a server. The server replies with an HTTP status code, a three-digit number that lets your browser know how things went. These codes inform whether your request was a success, redirected, encountered an error, or something else entirely.

Everyone knows the dreaded soft 404 code, signaling a page couldn’t be found. Or the “302” code, which tells us that the resource was temporarily moved to a different URL. Each of these codes has a specific meaning and falls into categories ranging from successful operations to server errors.

Why are these codes crucial for SEO? Because they directly affect how search engines interact with your site. Search engines like Google use these codes to determine how to index your site. For example, a “200 OK” status tells search engines that a page is good to go and should be indexed. On the other hand, a “301 Moved Permanently” suggests that the content has shifted, prompting search engines to update their records.

This can directly impact your site’s visibility and rankings in search results, making these codes essential tools in your SEO toolkit.

If you’re noticing unexpected drops in traffic or issues with page indexing, checking your site’s HTTP status codes is a great first step in troubleshooting. Remember, a well-maintained site is a well-ranked site.

The Complete List of HTTP Status Codes

CategoryStatus CodeDescription
1XX — Informational100Continue
101Switching Protocols
103Early Hints
2XX — Success200OK
204No Content
3XX — Redirection301Moved Permanently 
304Not Modified
4XX — Client Error400Bad Request
404Not Found
429Too Many Requests
5XX — Server Error500Internal Server Error
503Service Unavailable
504Gateway Timeout

HTTP Status Codes Explained

These codes tell you precisely what happened when a browser requested a page from a server, which can help you diagnose issues, optimize your site, and improve user experience.

Below, I’ve outlined a comprehensive list of HTTP status codes grouped by their first digit, indicating the response type the server has provided. Let’s break it down:

1XX HTTP Status Codes

  • 100 Continue: The server has received the request headers, and the client should proceed to send the request body.
  • 101 Switching Protocols: The requester has asked the server to switch protocols and the server has agreed.
  • 102 Processing: The server has received and is processing the request, but no response is available yet.
  • 103 Early Hints: Used to return some response headers before the final HTTP message.

2XX HTTP Status Codes

  • 200 OK: The request has succeeded, and the result of the request is transmitted in the response.
  • 201 Created: The request has been fulfilled and resulted in the creation of a new resource.
  • 202 Accepted: The request has been accepted for processing but still needs to be completed.
  • 204 No Content: The server successfully processed the request but is not returning any content.

3XX HTTP Status Codes

  • 301 Moved Permanently: The URL of the requested resource has been changed permanently. The new URL is given in the response.
  • 302 Found: The server has found a temporary redirection. This URL should be used again for the next time since it is only temporary.
  • 304 Not Modified: There is no need to retransmit the requested resources. It has not been modified since the last request.

4XX HTTP Status Codes

  • 400 Bad Request: The server cannot or will not process the request due to something that is perceived to be a client error.
  • 403 Forbidden: The server understood the request but refuses to authorize it.
  • 404 Not Found: The requested resource could not be found on the server.
    • There are also what’s called “soft 404s,” when the server responds with a 200 OK HTTP code for a page that doesn’t exist.
  • 429 Too Many Requests: The user has sent too many requests in a given amount of time (“rate limiting”).

5XX HTTP Status Codes

  • 500 Internal Server Error: The server encountered an unexpected condition that prevented it from fulfilling the request.
  • 503 Service Unavailable: The server is not ready to handle the request, often due to maintenance or overload.
  • 504 Gateway Timeout: The server, while acting as a gateway, did not receive a timely response from an upstream server.

This list is a quick reference to understand each code’s meaning and when they are typically used. By mastering this list, you can better diagnose issues with your website, enhance its reliability, and improve overall site performance. Understanding these codes is also crucial for technical SEO audits, ensuring that search engines can successfully crawl and index your site without stumbling upon critical errors that could hurt your rankings.

Why Are HTTP Status Codes Important for SEO?

These codes play a significant role in how search engines like Google view and handle your site. Here’s why every SEO should keep a close eye on these status codes:

  • Indexing and Crawling: Search engines use crawlers to index your website’s content, and the right HTTP status codes ensure these bots navigate your site effectively. For example, a “200 OK” status code tells search engines that a page is ready and available for indexing, while a “301 Moved Permanently” helps transfer the SEO value from an old page to a new URL.
  • Page Rank Distribution: HTTP status codes can influence how link equity, also known as “link juice,” is passed around your site. Codes like “301 Moved Permanently” preserve this equity, while codes like “302 Found” might not always pass on full link equity, affecting your site’s ranking potential. This is because Google recognizes “302 Found” as a temporary change.
  • User Experience and Ranking: User experience is a significant ranking factor. Status codes like “200 OK” enhance user experience by confirming that the site works as expected. Conversely, encountering a “404 Page Not Found” can frustrate users and increase bounce rates, which negatively impacts SEO rankings.
  • Technical SEO Audits: Regular SEO audits are vital for maintaining the health of your website. Part of this involves checking for proper HTTP status codes. Detecting and correcting error codes like “500 Internal Server Error” or “404 Not Found” can prevent SEO issues before they start impacting your site’s performance.

Understanding these codes and their implications can also help you manage redirect chains effectively. A redirect chain occurs when a page redirects multiple times before reaching the final destination, potentially diluting SEO value and slowing down page load times. Managing these chains requires understanding HTTP status codes like “301” and “302” to ensure the most efficient path for both users and search engines.

So, whether it’s smoothing out the user journey on your site, ensuring effective crawling and indexing, or performing comprehensive technical SEO audits, mastering HTTP status codes is an indispensable skill for optimizing your SEO strategy.

4 HTTP Status Codes SEOs Should Know

Not all HTTP status codes are created equal. Some have a more significant impact on your site’s performance and rankings than others. Here are four HTTP status codes that you should know inside and out, along with why they matter for your SEO efforts:

  • 200 OK: This is the gold standard of HTTP status codes. It means that your request was successful, and the server delivered the requested page correctly. For SEO, a “200 OK” status is crucial because it indicates that your pages are accessible and providing the content that was expected, which is essential for both users and search engines.
A 200 OK message in Google Search Console.

Source: SEMRush

  • 301 Moved Permanently: A 301 status code is vital for SEO because it tells search engines that a page’s URL has been permanently changed and redirects the user to the new URL. It’s crucial for maintaining a site’s domain authority and search rankings because it passes most of the SEO value from the old URL to the new URL. If you’re restructuring your site or changing domain names, using a 301 redirect is a must to preserve your SEO efforts.
A redirection in WordPress.

Source: Ahrefs

  • 404 Page Not Found: A 404 error occurs when the server can’t find the requested page. This code is particularly important for SEO because too many 404 errors can harm your site’s usability and reputation with search engines. Regularly fixing 404 errors ensures that you’re not losing valuable traffic and that search engines aren’t wasting resources trying to index pages that don’t exist. Tools and strategies for fixing 404 errors are essential for any SEO toolkit.
A 404 message on Neil Patel's website.

Source: NP Digital

  • 5XX Server Errors: These codes indicate problems with the server that prevented it from fulfilling the request. Common ones include “500 Internal Server Error” and “503 Service Unavailable.” These errors can significantly impact your SEO because they make your site appear unreliable both to users and search engines. Monitoring and quickly resolving these errors can help maintain your site’s credibility and usability.
A 500 server error on Google Chrome

Source: HubSpot

Understanding these status codes can help you better manage your website’s health and optimize its performance in search rankings. 


HTTP status codes play a crucial part in your SEO and content marketing strategy. Mastering these codes allows you to enhance your site’s architecture and ensures your content is delivered smoothly and efficiently to both users and search engines.

Remember, the smoother your site’s technical details, the better the user experience, which in turn boosts your SEO results.
Embrace these codes as foundational elements in your content marketing strategy to ensure your content reaches and resonates with your audience effectively.

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