5XX Errors These are fatal errors that will prevent anyone, including search engines, from accessing your website. They are normally caused from a programming bug or a server misconfiguration.

4XX Errors These errors normally occur because a page does not exist (404), it requires authentication (401) or it is forbidden to access the page (403). Make sure you deal with each type of code appropriately to ensure the page can be crawled.

Large Page Size In order to keep page load time low, you should try to minimize the amount of content and HTML contained in it. Generally, a page file size should be less than 1 MB in order to avoid any search engine penalties. Please note: Because this test is connected with search optimization and content, it may fail if the page is missing its canonical tag.

Page contains link relation conflicts By mixing commands to search engines as to whether to index or not index your page, this can lead to URLs not being indexed, decreasing overall search ranking.

Page contains a redirect chain A redirect chain is a page that contains multiple redirects between the source and target URL. Redirect chains can delay/reduce page crawling, increase page load time, and cause overall loss of link equity. It is a good idea to eliminate these whenever possible. Please note: Because this test is connected with search optimization and content, it may fail if the page is missing its canonical tag.

Page contains canonical links to broken pages Canonical links on the page point to pages that respond with a 4xx or 5xx code. This can confuse search engines, and causes them to ignore canonical links.

Duplicate Title Tags The page has more than one title tag. This can confuse a search engine as to which title to show, negatively affecting ranking. Please note: Because this test is connected with search optimization and content, it may fail if the page is missing its canonical tag.

Recursive Canonical Error The page contains rel='canonical' tag to another page, which in turn, refers back to the initial page. This will confuse search engines as to which page is canonical, negatively affecting rank

Canonical Chain The page has a canonical tag referring to a page, which in turn, has a canonical tag referring to a different page. This will confuse search engines as to which page is canonical as there are multiple canonicals to consider, which negatively affects the rank

Page contains canonical links to redirects When a canonical link points to a redirect, it sends a conflicting message to search engines. This can lead to incorrect URLs being indexed, resulting in potential duplicate content issues.

Missing Title A <title> tag is one of the most important components of a page. It is often used as a link to your page on a search engine and is meant to describe the purpose of the page in a few words. Please note: Because this test is connected with search optimization and content, it may fail if the page is missing its canonical tag.

Duplicate Titles A title is considered to be a duplicate if it matches the exact title of another page. Duplicate titles will diminish the quality of a page since it is unclear on which page has more relevance to a given topic. Furthermore, it will also confuse the user when navigating your site.

Duplicate Content A page is considered to have duplicate content if it contains very similar text to another page. Duplicate content will diminish the quality of a page since it is unclear on which page has more relevance to a given topic. Since there would be no purpose for a search engine to index the same page twice, it may ultimately lead to banning both pages from the results.

Broken Links A link is considered broken when the page cannot be accessed. This could be because it does not exist or there is an error trying to connect to it. Make sure the URL is inputted correctly and that you clear up any issues with the page. Excessive broken links will not only impact your visitors experience, it may also cause search engines to diminish the importance of your website.

Broken Resources A resource (image, stylesheet, script) is considered broken when it will not load. This could occur because the file does not exist or the resource could be too large and is randomly timing out when trying to load it.

Duplicate Descriptions A meta description is a hidden tag that describes the purpose of a page. Search engines may use this description in the listing for this site and in determining the topic of the page. If the same description is used on other pages, it maybe be difficult to differentiate between pages. Make sure meta descriptions are unique and use topical keywords to describe the content of the page.

Page is not Canonical Canonical tags help to avoid duplicate content when an unique content is accessible via multiple urls. Defining a correct canonical tag for all pages will keep them away from possible duplicate issues.

Low Readability Rate Readability is a major factor in page content by making your content understandable. Pages with low readability have scored less than 15 points on the Flesch–Kincaid readability test. Please note: Because this test is connected with search optimization and content, it may fail if the page is missing its canonical tag.

Missing Alt Attributes An alt attribute is used to describe an image in a textual context. Search engines may interpret an alt tag to identify the purpose of the image. This is a great way to increase your page relevance as it relates to a topic. Please note: Because this test is connected with search optimization and content, it may fail if the page is missing its canonical tag.

Irrelevant Description The page description tag is irrelevant to the content of a page. This can result in a negative user experience, which can harm your overall site's SEO ranking. Please note: Because this test is connected with search optimization and content, it may fail if the page is missing its canonical tag.

Irrelevant Title The page title is irrelevant to the content of a page. This can result in a negative user experience, which can harm your overall site's SEO ranking. Please note: Because this test is connected with search optimization and content, it may fail if the page is missing its canonical tag.

Low Word Count This test fails if the number of words on a page is less than 200. If a page does not have much content, it is hard for a search engine to properly assign a topic to it and may not bother indexing it. Try to make use of relevant content while using as many keywords as possible.

Depreciated HTML Tags Used Depreciated HTML tags may no longer be supported by modern browsers, leading to an overall negative user experience. These tags should be updated to supported tags whenever possible. Please note: Because this test is connected with search optimization and content, it may fail if the page is missing its canonical tag.

Long Title Any title with more than 65 characters is generally considered to be too long. Most search engines and sites will automatically shorten such a long title. A long title could penalize your site especially if you are keyword stuffing. Please note: Because this test is connected with search optimization and content, it may fail if the page is missing its canonical tag.

Short Title Generally, using short titles on web pages is a recommended practice. Having a title containing more than 30 characters should provide enough information about what your web page is about and assist your page’s potential to show up in search results for different keywords. Please note: Because this test is connected with search optimization and content, it may fail if the page is missing its canonical tag.

Duplicate Meta Tags The page has more than one meta tag of the same type. Please note: Because this test is connected with search optimization and content, it may fail if the page is missing its canonical tag.

Low Content Rate The amount of text compared to HTML tags represents your text to HTML ratio. This test will fail if the ratio is less than 10%. A search engine can only look at your text to determine the page's relevance. If there is an abundance of HTML compared to actual content, it will have difficulty segmenting the content. Furthermore, too much HTML may cause your page to load much slower. Please note: Because this test is connected with search optimization and content, it may fail if the page is missing its canonical tag.

Flash Content Used It is generally a bad idea to use flash on your website. It isn't possible for a search engine to interpret flash content and may skip over your page when crawling it. Furthermore, it creates a bad user experience as they will have to wait for it to load and may not be able to see anything on their mobile device.

SEO Friendly URL The page does not contain an SEO-friendly URL. Pages are not SEO-friendly if they contain special characters, dynamic parameters, are greater than 120 symbols, or are not relevant to the page. Please note: Because this test is connected with search optimization and content, it may fail if the page is missing its canonical tag.

Frames Used Using HTML frames are considered to be dated and should be avoided. It is difficult for a search engine to read them and creates a bad user experience. Try to remove any frames from your pages in favour of better and newer methods to accomplish the same thing.

Page contains render blocking resources Render blocking resource are static files that stop the downloading of additional resources until it is completed. Render blocking resources can increase load and wait time, negatively affecting user experience, and for that reason, they should be avoided if possible. Please note: Because this test is connected with search optimization and content, it may fail if the page is missing its canonical tag.

Low Character Count Indicates whether the page has less than 1024 characters. Please note: Because this test is connected with search optimization and content, it may fail if the page is missing its canonical tag.

Page contains a meta refresh redirect The page has a <meta http-equiv=”refresh”> tag that instructs a browser to load another page after a specified time span. From an SEO point of view, a meta refresh redirect is not the most optimal way of redirecting because it is actually a page refresh rather than a redirect. It is recommended that 301 redirects be used instead. Please note: Because this test is connected with search optimization and content, it may fail if the page is missing its canonical tag. Keywords contained in the meta keywords tag are irrelevant to the content of a page. This can result in a negative user experience, which can harm your overall site's SEO ranking. Please note: Because this test is connected with search optimization and content, it may fail if the page is missing its canonical tag.

Irrelevant Meta Keywords Keywords contained in the meta keywords tag are irrelevant to the content of a page. This can result in a negative user experience, which can harm your overall site's SEO ranking. Please note: Because this test is connected with search optimization and content, it may fail if the page is missing its canonical tag.

Has misspelled content Spelling mistakes can negatively affect user experience. Spell-checking should always be performed before publishing content to the web.

High Content Rate Indicates whether a page has the plaintext size to page size ratio of more than 0.9. Please note: Because this test is connected with search optimization and content, it may fail if the page is missing its canonical tag.

Page Contains Lorem Ipsum Content Lorem Ipsum content is placeholder text for determining page layout. Lorem ipsum text should be replaced with unique and relevant website content, otherwise search engines may find the page not relevant or duplicate. Please note: Because this test is connected with search optimization and content, it may fail if the page is missing its canonical tag.

Page does not have internal links pointing to it Orphaned pages stand a very, extremely low chance of ranking well in SEO terms. This tells search engines that the pages are unimportant and (likely) unworthy of indexation.

Missing H1 H1 tags are considered to be the main heading of a page and are used to help define the topic of the page. Creating a descriptive heading is an effective way to improve your search engine presence and make it easier for a user to navigate your page. Please note: Because this test is connected with search optimization and content, it may fail if the page is missing its canonical tag.

Meta Robots Blocking Crawlers The page’s ‘meta robots’ tag contains “nofollow” parameter instructing crawlers not to follow the links on the page.

Missing Meta Description A meta description is a hidden tag that describes the purposes of a page. Search engines may use this description in the results listing and in determining the topic of the page. Make sure each of your pages has a meta description that is unique and topical. Please note: Because this test is connected with search optimization and content, it may fail if the page is missing its canonical tag.

Page contains HTTP links HTTPS page has links to HTTP pages. HTTPS pages provide a rankings boost for your site, and linking to less secure links can negatively impact your SEO ranking. Please note: Because this test is connected with search optimization and content, it may fail if the page is missing its canonical tag.

Too Many On-Page Links This test will fail if a page has more than 200 links. Having too many links on a page can overwhelm the user and offer too many exit options. Search engines also have a limit on the numbers of links that they crawl on a page.

Redirect Links Links to redirected pages involve a network overhead and potentially slower navigation for the end user. It could also negatively impact the SEO. For this reason it's generally preferred to have direct links rather than redirects. A slow page can be frustrating for a user and will lower your relevance in the eyes of a search engine. Most users will not put up with a slow page and go elsewhere. A search engine understands this and will do the same. This test fails if it takes longer than 3 seconds to load the page.

Slow Page Load A slow page can be frustrating for a user and will lower your relevance in the eyes of a search engine. Most users will not put up with a slow page and go elsewhere. A search engine understands this and will do the same. This test fails if it takes longer than 3 seconds to load the page.

Encoding not Declared Specifying an encoding for a page will ensure that each character is displayed properly. Generally this usually set to utf-8 but depending on the language of the page, this could be different. Example: <meta charset='utf-8'>. Please note: Because this test is connected with search optimization and content, it may fail if the page is missing its canonical tag.

Doctype not Declared A doctype is the first thing that appears in your page's source code and instructs a web browser which version of HTML you are using. If this is not specified then your code could be interpreted incorrectly and become uncrawlable.

Missing Https Redirect Every website should be accessible securely with an https url. In order to make sure that you're always using https, your website should redirect any request from http to https.

Missing Favicon Although a missing favicon will not have a direct affect on SEO, but having a favicon for your site will provide increased usability by showing your icon in bookmarks and browser tabs. Please note: Because this test is connected with search optimization and content, it may fail if the page is missing its canonical tag.

High Waiting Time Indicates whether a page waiting time (aka Time to First Byte) exceeds 1.5 seconds. A slow page can be frustrating for a user and will lower your relevance in the eyes of a search engine. Most users will not put up with a slow page and go elsewhere. A search engine understands this and will do the same.

High Character Count Indicates whether the page has more than 256,000 characters. Large character counts can impact site performance, decreasing overall SEO. Please note: Because this test is connected with search optimization and content, it may fail if the page is missing its canonical tag.