HTTP Status Codes: Your Ultimate Guide to Web Server Responses

Written by The Valve+Meter Team / March 14, 2024 / 12 Minute Read
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Mastering HTTP status codes is crucial for website success. This comprehensive guide explains these digital signals, helps you troubleshoot errors, and shows how to leverage them for better user experience and search engine optimization.


Facing a web page error can be all too familiar or downright puzzling.

Each of the HTTP status codes offers a clue, whether it’s a smooth ‘200 OK’ or the maddening ‘404 Not Found’.

This guide deconstructs these digital signals, helping you troubleshoot issues and optimize your site’s trustworthiness for users and search engines alike, with a focus on http status codes.

Key Takeaways

  • HTTP status codes are critical communications from a web server indicating the success or failure of a browser’s request.
  • Status codes are categorized into five classes:
    • 1xx: Informational responses
    • 2xx: Successful operations
    • 3xx: Redirections
    • 4xx: Client errors
    • 5xx: Server errors
  • Effective management of HTTP status codes is key to maintaining a seamless user experience and can significantly impact SEO.

Understanding HTTP Status Codes

The internet is so ubiquitous to daily life that the interaction between your browser and a web server is easily forgotten.

Your browser requests a web page and receives a response from the server. HTTP status codes are the mechanism by which the server communicates the result of this request.

These are the digital pathways conveying your request for a webpage. Every time you visit a webpage, these codes are at work.

HTTP status codes usually work behind the scenes, but they become important when something goes wrong and you see an error message.

However, these codes do more than alert you to problems. They play a key role in how users navigate your website and how well your site performs.

Understanding HTTP status codes gives you the power to quickly fix website errors, make your site more user-friendly, and improve your search engine rankings. Let’s dive in and start learning this essential language of the web!

What are HTTP Status Codes?

Status codes are three-digit numbers included in the server’s response to a browser’s request, and they come in various flavors, each telling a different story.

This numeric system is a part of the HTTP (Hypertext Transfer Protocol), the foundation of data communication for the web.

The server tells the browser what happened with the request by embedding this information within the response headers. Some common status codes include:

  • 200 OK: The request was successful
  • 404 Not Found: The requested resource could not be found
  • 500 Internal Server Error: There was an error on the server
  • 301 Moved Permanently: The requested resource has been permanently moved to a new location

Understanding these status codes can help you troubleshoot issues and optimize your website’s performance.

These headers, including the expect request header field, are a critical component of the HTTP transaction, carrying metadata about the request or the returned content, such as the message body. Request header fields play a crucial role in this process. When a status code is issued, it’s accompanied by a reason phrase—a short, human-readable explanation of the code. This phrase can range from the reassuring “200 OK,” signaling all is well, to the ominous “404 Not Found,” hinting at a digital dead end.

Comprehending these codes and their implications is similar to being a web meteorologist—anticipating potential issues and maintaining a smooth experience for users, especially for future requests.

They are the cornerstone of effective web communication, as they inform the requesting party—be it a browser, a search engine bot, or any other client—of the outcome of their request and the next steps to take, if any.

Importance of HTTP Status Codes

Status codes act as the heartbeat of a website, providing immediate insights into its health. They play a pivotal role in maintaining accessibility and providing crucial information about a site’s availability and performance.

For example, a “200 OK” code indicates that everything is functioning as expected, but it doesn’t end there. It doesn’t guarantee that the content returned is exactly what was anticipated, which is why understanding these codes is vital for more than just troubleshooting errors.

These codes profoundly shape the user experience. They’re the unseen guides that lead users when they’ve veered off course to a non-existent page or inform them when a transaction is successfully completed.

For site owners and developers, they’re the first responders, rushing to the scene when there’s a glitch, to quickly diagnose and remedy issues.

Additionally, these codes converse with search engines, influencing SEO. A site riddled with “404 Not Found” errors is a red flag, potentially leading to lower search rankings. Conversely, a clean bill of health, with mostly “200 OK” responses, can contribute to a site’s credibility and ranking. In essence, mastering HTTP status codes is not just about fixing problems—it’s about creating a streamlined, accessible, and enjoyable online experience for everyone.

Infographic of HTTP Status Code Categories

Categories of HTTP Status Codes

Exploring further into the realm of HTTP status codes uncovers five distinct categories, each representing a unique type of response.

These categories are determined by the first digit of the status code and provide a quick way to understand the server’s message.

It’s a bit like sorting your mail into categories: some are greetings, some are invitations, and others might be bills—or, in the case of status codes, error messages.

The HTTP status codes can be categorized as follows:

  1. Informational codes (1xx): These codes indicate that the request has been received and the process is ongoing.
  2. Success codes (2xx): These codes signal success, indicating that your request not only made it to the server but also fit the bill perfectly.
  3. Redirection codes (3xx): These codes inform you that what you’re looking for is somewhere else and provide redirection instructions.
  4. Client error codes (4xx): These codes suggest that the problem might be on your side, such as a typo in the URL or a wrong link.
  5. Server error codes (5xx): These codes signify server errors, indicating that the server itself is experiencing issues. Each status code indicates a specific issue that must be addressed.

Understanding these codes can help you troubleshoot and resolve any issues you encounter while browsing the web.

Each of these categories fulfills a distinct role in the digital exchange between clients and servers. By familiarizing yourself with these categories, you become fluent in interpreting the server’s responses, whether you’re troubleshooting, optimizing for SEO, or ensuring a seamless user experience.

Infographic 1xx http status codes

1xx Informational

The 1xx category can be likened to the server saying, “Patience, I’m in progress!” These codes are preliminary, keeping the lines of communication open while the server processes the request.

Think of it as the acknowledgment you receive when you’ve sent an important email: the recipient has seen it, and you can expect further details soon.

A “100 Continue” code, for example, is the server’s nod for the client to go ahead and send the rest of the information. If you’ve ever seen a progress bar during an upload, that’s the 1xx code in action. And while these informational codes are less commonly encountered by the average user, they play a crucial role in optimizing data transfer, especially when dealing with large requests.

This category is fundamental for maintaining an efficient flow of information. It ensures that clients don’t jump the gun and that servers are given the time they need to handle requests methodically.

As such, 1xx codes are the unsung heroes that maintain the equilibrium of web traffic.

2xx http status codes infographic

2xx Successful

A 2xx status code from a server is a reason to rejoice—it signifies success!

These codes are affirmative responses, confirming that the server received, understood, and accepted the request. It’s akin to a chef at a restaurant nodding affirmatively to your order and then delivering the dish exactly as requested.

In this case, the response code serves as a clear indicator of successful communication between client and server.

The most well-known code in this category is “200 OK,” the digital thumbs-up indicating that the server has successfully processed the request and the browser can present the content. It’s the status code equivalent of a handshake, signifying that all is well in the exchange between client and server.

Success codes underpin a seamless web browsing experience. They’re the silent affirmations that keep users engaged and contented, often going unnoticed because everything is working just as it should.

Without these codes, we’d be adrift in a sea of uncertainty, never quite sure if our digital requests had reached their intended destination.

3xx HTTP status code infographic

3xx Redirection

Web navigation can at times resemble a breadcrumb trail, with 3xx redirection codes serving as directional markers. They are the polite notifications from the server that what you’re looking for has moved, but don’t worry—it hasn’t gone far.

Imagine you’ve moved to a new house and left a forwarding address at the old one; that’s what the 301 Moved Permanently code does.

It tells anyone looking for the old page that there’s a new place to go, and this new address should be used from now on.

On the other hand, the 302 Found and 307 Temporary Redirect codes are like saying, “I’m just staying over here for a while, but my permanent address hasn’t changed.”

Redirection codes are essential for maintaining a seamless web experience.

They preserve link value, guide users and search engines to the correct content, and support the ever-changing nature of websites. Understanding how to use them effectively is crucial for building a well-structured, easy-to-navigate website.

4xx HTTP Status Codes infographic

4xx Client Error

The 4xx category indicates, “Nothing found. The problem is on your end.”

It’s time to troubleshoot! Check your URL, clear your cache, or try again – the solution is likely on your side.

These codes indicate that the issue lies with the client’s request, which the server is unable to process.

Some common HTTP status codes include:

  • 404 Not Found: indicates that the page you’re looking for simply isn’t there
  • 401 Unauthorized: means you need to log in to proceed
  • 403 Forbidden: equivalent of being told you can’t enter even with a valid ticket

These codes are important for understanding and troubleshooting website errors.

Client error codes serve as an action prompt. They prompt users to check their client request, clear cache, or simply inform them that they’ve hit a dead end.

For developers and site owners, these codes are vital clues in the quest to enhance user navigation and rectify issues that could lead to a poor user experience or damage SEO rankings.

5xx HTTP Status Codes infographic

5xx Server Error

When a 5xx status code emerges, it’s the server’s distress signal—indicating an issue on its end.

The “500 Internal Server Error” is a generic distress signal, implying that something unexpected has stopped the server from delivering the content.

These codes are a clear indication that the server is experiencing difficulties and can’t complete the client’s request. Think of it as a temporary setback – your request is on hold until the issue is resolved.

Different codes within this series offer clues about the specific problems. For example, “503 Service Unavailable” might suggest a scheduled maintenance break, or “505 HTTP Version Not Supported” could indicate a compatibility issue between the server and your browser.

These server error codes are crucial for diagnosing deeper issues that could have a significant impact on a site’s functionality and user experience.

They highlight the importance of regular server maintenance and the need for contingency plans to handle unexpected downtimes or traffic spikes.

Common HTTP Status Codes and Their Meanings

Despite the wide range of HTTP status codes available, only a select few are commonly experienced during regular web browsing. These common codes act as signposts, directing the flow of internet traffic and influencing how we interact with websites.

Understanding them is like having a cheat sheet for the most common web hiccups and knowing how to deal with them effectively.

When working with websites, it’s essential to be familiar with the list of HTTP status codes. Some common HTTP status codes include:

  • “200 OK”: A task well accomplished, an affirmation that everything is in order
  • “404 Not Found”: The content you were seeking has vanished, at least from where it was supposed to be
  • “500 Internal Server Error”: A malfunction on the server’s side that needs immediate attention

These and other status codes are the language web servers communicate with users and search engines. They’re the difference between a seamless browsing experience and a frustrating one, between a well-optimized site and one that struggles to climb the SEO ranks.

common HTTP status codes

200 OK

The “200 OK” status code is the green light of the web, signaling all systems go. It’s the most common code you’ll encounter, typically because it’s the response you get when everything works perfectly.

Whether you’re submitting a form, posting on social media, or just clicking a link to read an article, “200 OK” means your request was received, understood, and processed without a hitch.

This code is versatile, applicable to any request method—whether you’re GETting a webpage, POSTing data to a server, or PUTting an update to a resource. It’s the digital handshake that concludes a successful transaction, the server’s confirmation that your request entity has been fulfilled as expected.

Understanding the “200 OK” code is essential because it’s the benchmark for normal web operations. When monitoring website performance, this is the code you want to see consistently. It’s the status code that, while often taken for granted, is the bedrock of a smooth, user-friendly web experience.

404 Not Found

The “404 Not Found” status code is the internet’s equivalent of a missing person’s poster. It’s the response you get when the server can’t find what you’re looking for, no matter how hard it digs.

This could be due to a page being moved without a redirect in place, a mistyped URL, or a link pointing to content that’s been removed.

This error is a common frustration for users, but it’s also a crucial signal for website owners. A well-crafted 404 page can turn a potential dead-end into an opportunity to engage visitors, guiding them back to active parts of the site or offering them a way to report the missing page.

It’s also important for SEO, as having too many 404 errors can be a sign of a poorly maintained site, which search engines don’t appreciate.

Dealing with “404 Not Found” errors involves a mix of preventative and reactive measures, including:

  • Ensuring proper redirects are in place
  • Creating a helpful custom 404 page
  • Regularly monitoring and fixing broken links
  • Submitting an updated sitemap to search engines
  • Using a website monitoring tool to identify and fix 404 errors promptly

By implementing these measures, you can minimize the occurrence of these errors and handle them gracefully when they do happen.

500 Internal Server Error

The dreaded “500 Internal Server Error” is the digital world’s cry for help. This status code is a catch-all response for when the server encounters an unexpected condition that prevents it from fulfilling a request.

It’s a broad, generic signal that something has malfunctioned behind the scenes, akin to a “check engine” light in a car—you know there’s a problem, but without further investigation, you can’t determine the specific issue.

Encountering a 500 error can be as disconcerting for users as it is for webmasters.

For the latter, it prompts an immediate investigation into server logs and configurations to identify the root cause, which could range from:

  • Permissions issues
  • Script errors
  • Resource limitations
  • Server crashes

This status code, often indicating an invalid response, means that the server, specifically the origin server, requires a reminder of the importance of robust server infrastructure, diligent monitoring, and a timely response to avoid too many requests.

For the average user, a 500 error is a sign that their action cannot be completed—at least not right now. It also reflects on the website’s reliability and can significantly impact a user’s perception of the brand. Therefore, addressing these errors swiftly is critical to maintain user trust and prevent a negative impact on SEO.

301 Permanently Moved

The “301 Permanently Moved” status code is like the change of address notice you file with the post office when you move to a new home. It tells the internet that the page you’re looking for has permanently moved to a new location and that all future requests should be directed there.

This status code is crucial for maintaining the SEO value of a page when its URL changes.

Instead of losing the accumulated search engine rankings, a 301 redirect passes most of this value to the new URL.

It’s also a way to ensure a smooth user experience. When visitors follow an old link or bookmark, they are seamlessly redirected to the new page without encountering a 404 error.

Handling “301 Permanently Moved” correctly involves setting up server-side redirects, usually through the .htaccess file on Apache servers or the web.config file on IIS servers. It’s important to update internal links and inform search engines of the change through sitemaps and webmaster tools to prevent any negative impact on your site’s performance.

Managing HTTP Status Codes for Better Performance

Managing HTTP status codes effectively goes beyond just damage control; it’s about proactively establishing a robust, user-friendly environment that is favored by search engines. Status codes are the gatekeepers of web performance and SEO. Handling them correctly can be the difference between a site that thrives and one that merely survives.

Errors, particularly those in the 4xx and 5xx categories, require immediate attention to avoid long-term adverse effects on user experience and search rankings. Some actions you can take to address these errors include:

  • Creating a custom 404 page to engage and retain users
  • Swiftly resolving 500 errors to maintain a professional online presence
  • Setting up 301 redirects for URLs that have changed to retain the SEO value of the original page.

Managing status codes effectively involves regular website audits, fixing broken links, and using the correct type of redirects—301 for permanent changes and 302 for temporary ones. It’s about ensuring that the flow of ‘link juice’ remains uninterrupted and that the website’s map is clear for both users and search engines to follow.

Identifying and Fixing Common Errors

In the digital landscape, errors are inevitable, but letting them linger is not. Identifying and fixing common HTTP status code errors is a critical task for maintaining a seamless user experience and solid SEO foundation. Addressing these errors promptly can avert the risk of losing traffic and deteriorating search engine trust.

For 4xx client errors, troubleshooting steps might include verifying the spelling of URLs, ensuring that login credentials are correct, or setting up a user-friendly custom error page to guide lost visitors. On the server side, a 500 Internal Server Error may require a deep dive into server logs or even upgrading server resources to handle increased loads or complex scripts.

Fixing such errors is akin to maintaining a well-oiled machine. It ensures that every part of your website functions smoothly and that the user journey remains uninterrupted. It’s not just about quick fixes but also about implementing long-term solutions that prevent future occurrences, thereby fostering a reliable and efficient web environment.

Redirects and SEO

Redirects are a vital tool in the webmaster’s arsenal, serving as detour signs that guide traffic along the desired path.

When it comes to SEO, the impact of redirects is significant. Search engines use status codes to understand how to handle redirected URLs. A well-implemented redirect strategy can ensure that a page’s SEO value is preserved even when its location changes.

A “301 Moved Permanently” redirect should be used when a page has been permanently relocated. This status code tells search engines that the old page’s SEO value should be transferred to the new URL.

Conversely, a “302 Found” redirect indicates a temporary move, and link equity is not passed on—a crucial distinction for maintaining a site’s ranking power.

In addition to selecting the right type of redirect, avoiding redirect chains and ensuring that redirects don’t create loops are critical for SEO. Redirects can also help recover SEO value from broken external links by directing them to relevant content.

By mastering the use of redirects, you can ensure that your site’s navigation is seamless, and its SEO potential is fully realized.

Tools for Monitoring and Debugging HTTP Status Codes

In the ever-changing digital world, maintaining a close watch on HTTP status codes is vital for any website owner or developer. Thankfully, a range of tools exists to help monitor and debug these codes, ensuring that you can swiftly identify and address issues before they escalate.

These tools are the diagnostics equipment for websites, constantly scanning and reporting on the health of web pages. Some of these tools include:

By utilizing these tools, you can stay on top of your website’s performance and ensure a smooth user experience.

Browser developer tools, like Chrome DevTools, are indispensable for real-time monitoring of HTTP transactions. They allow developers to see status codes as they happen, providing instant insights into the communication between the client and server. These tools can also help pinpoint the cause of errors, offering clues through headers and response bodies.

For broader monitoring, online checkers and crawlers offer functionalities that range from bulk checking URLs for status codes to setting up automated alerts for when errors are detected. These tools can provide comprehensive reports, making them invaluable for large-scale websites where manual checking isn’t feasible.

Regular use of these tools is a best practice for proactive website management and maintaining a clean SEO profile.

Browser Developer Tools

Browser developer tools serve as a multi-tool for web professionals, brimming with features for inspecting, testing, and debugging web pages. Among these features is the ability to monitor HTTP status codes, a crucial capability for understanding the interactions between a user’s browser, or user agent, and web servers.

The Chrome DevTools Network Panel, for instance, offers a real-time view of all network requests made by the browser, complete with status codes. By looking at the Status column, developers can see at a glance whether a resource loaded successfully or if there were redirections, client errors, or server errors. This immediate feedback is invaluable for diagnosing issues and ensuring a website’s responsiveness, and helping developers gain network access insights.

Moreover, these tools can delve into the specifics of each HTTP transaction, displaying request and response headers, previewing response bodies, and even showing the timing of each network event. This level of detail equips developers with the data they need to troubleshoot effectively and optimize web performance.

Online Checkers and Crawlers

When managing a large website, tracking HTTP status codes on numerous pages can be daunting. Online checkers and crawlers lighten the load of this task, offering automated solutions that:

  • Sweep through and report status code issues across a site
  • Act as vigilant sentinels, watching over a website’s health
  • Alert you to changes and potential problems

These tools are the vigilant sentinels, watching over a website’s health and alerting you to changes and potential problems., for example, simplifies the process of checking HTTP status codes with a user-friendly interface and useful features like mass testing and data export. It’s a tool designed for efficiency, allowing webmasters to quickly assess the status of multiple URLs—whether for routine checks or during site migrations.

These online services not only reveal the current status of web pages but can also uncover redirect chains, which can affect load times and SEO. They highlight the importance of regular health checks for websites, ensuring that all pages are accessible and performing as intended.

By leveraging these tools, website owners can stay ahead of issues, maintaining an optimal online presence.

Close-up view of a glowing circuit board with electronic pathways, your ultimate guide to HTTP Status Codes.

List of HTTP Status Codes

1xx Informational

  • 100 Continue
  • 101 Switching Protocols
  • 102 Processing

2xx Success

  • 200 OK
  • 201 Created
  • 202 Accepted
  • 203 Non-Authoritative Information
  • 204 No Content
  • 205 Reset Content
  • 206 Partial Content

3xx Redirection

  • 300 Multiple Choices
  • 301 Moved Permanently
  • 302 Found (Previously “Moved temporarily”)
  • 303 See Other
  • 304 Not Modified
  • 307 Temporary Redirect
  • 308 Permanent Redirect

4xx Client Error

  • 400 Bad Request
  • 401 Unauthorized
  • 403 Forbidden
  • 404 Not Found
  • 405 Method Not Allowed
  • 406 Not Acceptable
  • 408 Request Timeout
  • 409 Conflict
  • 410 Gone

5xx Server Error

  • 500 Internal Server Error
  • 501 Not Implemented
  • 502 Bad Gateway
  • 503 Service Unavailable
  • 504 Gateway Timeout
  • 505 HTTP Version Not Supported


Navigating the waters of HTTP status codes can be a complex endeavor, but mastering them is essential for any web professional. These codes are the backbone of web communication, guiding users through their online journeys and informing search engines about the state of a website.

From the reassuring “200 OK” to the elusive “404 Not Found,” each code serves a specific purpose, shaping the user experience and impacting SEO.

Remember, handling these codes effectively is not just about resolving errors—it’s about creating a seamless, engaging online environment. By leveraging browser tools and online checkers, implementing strategic redirects, and maintaining a vigilant eye on server health, you can ensure that your website not only performs well but also climbs the ranks of search results, providing an optimal experience for all who visit.

Frequently Asked Questions

The 502 Bad Gateway error indicates that the server received an invalid response from another server. This can occur when an interim device like an edge server fails to fetch all the necessary data to load the page.

The main difference between a 201 and 204 response lies in their purpose and content. A 201 response indicates the successful creation of a resource, whereas a 204 response signifies a successful request without any data to return.

HTTP error codes 200, 400, and 500 are among the most common. The 200 OK status indicates a successful request, while 400 and 500 series codes indicate client and server errors, respectively.

Using the correct redirect is vital for maintaining a site’s SEO, as a 301 redirect indicates a permanent move of a web page, passing most of the original page’s SEO value to the new URL, while a 302 redirect is for temporary relocations and does not pass on link equity.

Yes, a well-designed custom 404 page can help maintain a positive user experience and site structure, mitigating the SEO impact of broken links.