HTTP Status Codes Explained: Full List & Impact on SEO
Expert reviewed
Our subject matter experts have reviewed this article to ensure it meets the highest standard for accurate information and guidance. Learn more about our editorial standards and process.
What Are HTTP Status Codes?
HTTP status codes are three-digit numbers servers generate in response to a client (e.g., a browser) request. They indicate whether the request was completed successfully.
For example, a 404 error is a common HTTP status code you might have seen.
If you’re a website owner, HTTP status codes give you important information for improving your website’s functionality and user experience. And they can impact your SEO.
Categories of HTTP Status Codes
There are five categories of HTTP status codes:
- 1XX (informational codes): The server received the request and is processing it
- 2XX (success codes): The server successfully received and processed the request
- 3XX (redirection codes):The server received the request, but there’s a redirect to another destination (301 or 302 are common)
- 4XX (client error codes):The requested resource couldn’t be found or reached due to a client error
- 5XX (server error codes): The server ran into an error when processing the request
A Complete List of HTTP Status Codes
How to Check a Webpage’s HTTP Status Codes
You can easily check a page’s HTTP status codes using Google Chrome.
Go to the webpage you want to check.
Right-click anywhere on the page and select "Inspect” to open the Developer Tools. Or press “Ctrl + Shift + I” (Windows/Linux) or “Cmd + Option + I” (Mac).
Click on the "Network" tab in the Developer Tools panel.
Refresh the page (select “F5” or “Ctrl + R”).
Look at the list of network requests.
The “Status” column shows you a list of HTTP status codes for the page. The first one in the list is the page’s HTML document.
It’s also a good idea to audit your site for HTTP status code errors. You can do this easily in Semrush’s Site Audit tool.
Simply run a crawl and click on “Crawled Pages.”
The “Status” column will show you the status code of each page so you can see if there are any errors that need fixing.
Check HTTP Status Codes
with the Site Audit Tool
The Implications of Common HTTP Status Codes for SEO
Here’s what some of the most common status codes mean for your SEO:
200 (OK)
A 200 response code is what you’ll want most of your webpages to return.
It indicates that a webpage works and is accessible to both people and search engines.
301 (Moved Permanently)
A 301 code means you’ve permanently moved a page to a new URL. And signals to Google that the old URL in its index should be replaced with the new one.
Importantly, a 301 redirect also transfers link equity from the old page to the new one. Which preserves your visibility.
302 (Found/Temporary Redirect)
A 302 redirect is a temporary redirect. It can preserve links and rankings while a webpage is temporarily unavailable.
For example, if you’re doing website maintenance and want to send users to a temporary holding page. Or you’re carrying out A/B testing.
If a 302 redirect is in place for a long time, Google may start treating it as a 301 redirect. Meaning the old URL will be replaced by the new one in Google’s index.
404 (Not Found) and 410 (Gone)
Both 404 and 410 status codes tell search engines that a page no longer exists, which typically leads to it being removed from the index.
While both ultimately lead to deindexing, a 410 more clearly communicates that the page is gone for good. This can speed up its removalfrom search engine indexes.
5XX (Server Errors)
Search engines have trouble accessing pages with 5XX errors, which can lead to problems with crawling, indexing, and the user experience.
Over time, this can negatively impact visibility in search results. So it’s important to monitor and resolve 5XX errors promptly.
The Impact of HTTP Status Codes on LLMs
It’s important to make sure your content’s accessible to tools built on large language models (LLMs), like Google’s AI Overviews, ChatGPT, Perplexity, and Claude. Because it’ll help you gain more visibility in those AI responses.
Status codes that signal errors—like 404s and 500s—can block LLMs from seeing your content. Because LLMs find and understand website content similar to traditional search engines.
Web developer and AI engineer Vincent Schmalbach notes:
“Sites with frequent HTTP status code errors may find their content underrepresented in both search results and AI-generated responses, since both systems require reliable access to index and utilize content effectively.”
Vincent adds the following when talking specifically about 4XX and 5XX status codes:
“Both 404 and 410 responses mean no content is available, so those pages don't contribute to training data. Server errors like 500s cause crawlers to retry later, but persistent errors result in content being skipped entirely.”
Toby Basalla, Founder and Principal Data Consultant at data analytics consultancy Synthelize, warns that a website with unintentional redirect status codes can skew data used to train the actual models if it's scraped all at once. Because those mistakes are difficult to spot among so much data.
He reflects on a notable experience running a custom-trained LLM that relied on a scraped dataset:
“In one case, a client had 180 landing pages misflagged as temporary redirects, and none of it made it into our scraped dataset. Which means, in effect, those pages did not exist to the model.”
Check Your Website for HTTP Status Code Errors
You should check your website’s HTTP status codes regularly to stay on top of any errors.
Semrush’s Site Audit tool makes it easy to identify any of these problems. So you can swiftly address issues and boost your SEO performance.
Find and Fix HTTP Status Code Errors
with the Site Audit Tool
Carlos Silva leads the editorial pipeline for the English blog—coordinating writers, editors, strategy, and building AI workflows that boost content quality and AI visibility. With 10+ years of experience writing and editing across in-house and agency roles, Carlos blends content strategy, SEO, and AI to help marketers stay ahead of an evolving search landscape.
Carlos Silva
Carlos Silva leads the editorial pipeline for the English blog and builds AI workflows that boost content quality and AI visibility. 10+ years writing and editing across in-house and agency roles.
Tells Google to show you more from Semrush in AI, Search, and Discover.