Audisto Crawler Hints
Technical Website Error Scanner Find & Fix Critical Issues
What is the error checker for
Detect Critical Technical Issues: Find HTML validation errors, malformed URLs, and broken implementations that could harm your website's functionality and user experience.
Ensure Security Compliance: Identify security-related issues like mixed content, improper CSP headers, and unsafe form submissions that could compromise your website's security.
Maintain SEO Best Practices: Catch technical errors affecting SEO such as canonical issues, improper meta tags placement, and conflicting robot directives.
Monitor Code Quality: Track implementation errors across your website to maintain high technical standards and prevent regressions.
How to check technical errors at scale
Prevention is better than cure
Technical errors can severely impact your website's performance, security, and search visibility. Our comprehensive error detection helps you identify and fix issues before they affect your business. While our quick check gives you immediate insights for single pages, our full crawler ensures your entire website stays error-free.
Critical Errors related hints
<*> has malformed or empty src attribute
This hint identifies all occurrences of html elements that contain an invalid target URL in the src attribute.Learn more
<a> has malformed href
If a malformed href is found, the URL is flagged with this hint.Learn more
<a> links to fragment by name attribute on non-anchor
The anchor contains a fragment link, but the target is defined by a name attribute and is not an anchor itself.Learn more
<a> links to fragment only, but <base> points to another URL
<a> links to fragment only, while there is a <base> pointing to another URLLearn more<a> links to fragment that was not found
The anchor contains a fragment link, like "#top", but there was no corresponding id or name attribute found in the document.Learn more<base>: Contains malformed or empty href
A <base> tag was found, but its href attribute contains an invalid URL, or a URL that is neither HTTP nor HTTPS.Learn more<base>: Found more than once and differs
More than one <base> directive are found with a differing href attribute value.Learn more<base>: Href contains a path only
The <base> tag's href attribute contains a path, not an absolute URL.Learn more<base>: Occurs more than once
More than one <base> tag was found.Learn more<form> POST to HTTPS from HTTP
The form posts to an HTTPS URL, but resides on an HTTP URL.Learn more<form> Unsafe GET to HTTP from HTTPS
A form uses the GET method and submits itself to an HTTP URL, but resides on an HTTPS URL.Learn more<form> Unsafe POST to HTTP from HTTPS
A form uses the POST method and submits itself to an HTTP URL, but resides on an HTTPS URL.Learn more<form> has malformed or empty action
This hint identifies all occurrences of <form> elements that contain an empty or invalid target URL.Learn more<html> contains too many uncommon non-printable characters
The HTML documents contains too many uncommon non-printable characters, and not all of them will be shown in live analysis.Learn more<html> contains uncommon non-printable characters
If uncommon non-printable characters are detected, the URL of the document containing the character is flagged.Learn more<html> starts with BOM
There is a unicode byte order mark (BOM) at the top of the HTML.Learn more<img> has no alt attribute
If an image without an alt attribute is found, the URL is flagged with this hint.Learn more<link rel=canonical>: Contains malformed or empty href
This hint identifies all occurrences of canonical elements that contain an invalid target URL.Learn more<link rel=canonical>: Found outside <head>
A canonical element was placed outside the <head> section and so search engines will ignore it.Learn more<link rel=canonical>: Found twice
More than one canonical element was found, either as a <link> tag with rel="canonical" or an according link header.Learn more<link rel=canonical>: Found twice and differs
More than one canonical element has been found, either as a <link> tag with rel="canonical" or an according Link header. Additionally, they specify different targets.Learn more<link> found outside <head>
A not allowed <link> tag was placed outside the <head> section where it may have no effect.Learn more<link> has empty, unknown or forbidden rel
This hint identifies all occurrences of <link> elements that contain rel attributes which are unknown, empty or forbidden.Learn more<link> has malformed or empty href
This hint identifies all occurrences of <link> elements that contain an empty or invalid target URL.Learn more<link> has rel and itemprop attribute
This hint identifies all occurrences of <link> elements that contain both a rel and an itemprop attribute.Learn more<meta description> occurs more than once
If a meta description is found more than once in the HTML, the URL is flagged with this hint.Learn more<meta> found outside <head>
A <meta> tag was placed outside the <head> section, where it may have no effect.Learn more<object> has malformed or empty data attribute
This hint identifies all occurrences of <object> elements that contain an empty or invalid target URL.Learn more<title> found outside <head>
A <title> tag was placed outside the <head> section, where it may have no effect.Learn more<title> missing or empty
If the <title> tag is missing, the URL is flagged with this hint.Learn more<title> occurs more than once
If the <title> tag is found more than once, the URL is flagged with this hint.Learn moreCharset: Charset set in HTTP Content-Type header and document differ
Both the document and the HTTP Content-Type header specify a charset, but these are not identical.Learn moreCharset: Invalid charset in Content-Type HTTP header
The Content-Type HTTP header specifies an invalid charset.Learn moreCharset: Invalid charset in Document
This hint identifies all HTML documents where the charset declaration in the HTML document specifies an invalid charset.Learn moreCharset: Not set
There is no charset set, neither in the Content-Type HTTP header, nor in the document, e.g. through a <meta> tag.Learn moreContent-Security-Policy HTTP header missing
If the Content-Security-Policy HTTP header is missing, the URL is flagged with this hint.Learn moreDuplicate id attributes
The same ID was assigned to several elements.Learn moreHreflang: Found outside <head>
An hreflang link was placed outside the <head> section and so search engines will ignore it.Learn moreLanguage: Content-Language http-equiv meta element found
A Content-Language declaration was found as http-equiv meta elementLearn moreLanguage: Invalid
Language found does follow some basic rules for language tags.Learn moreLanguage: Set multiple times and differs
The document language was set multiple times and differs.Learn moreRedirect: Loop member
This URL is an element in a redirect loop. A redirect loop is a chain of redirects that ultimately redirects to the start of the chain again.Learn moreRedirect: Loop starts here
This URL is the first element in a redirect loop. A redirect loop is a chain of redirects that ultimately redirects to this URL again.Learn moreRedirect: Non-ASCII characters in location URL
Only printable ASCII characters are allowed in HTTP header values and redirect location URLs.Learn moreRendering: Console errors
This hint identifies all HTML documents where rendering results in error message within the console output.Learn moreRendering: Content blocked by Content Security Policy
This hint detects all HTML documents where content rendering is blocked by a Content Security Policy during rendering.Learn moreRendering: Has JavaScript errors
This hint detects all HTML documents with JavaScript errors during rendering.Learn moreRendering: Inline content blocked by Content Security Policy
This hint detects all HTML documents where inline content is blocked by the Content Security Policy during rendering.Learn moreRobots: Specified more than once
Robots directives are specified more than once. If a document contains more than one robots definition, it will be flagged.Learn moreRobots: nofollow differs across specifications
There is more than one source for robots, either a robots meta tag or a X-Robots-Tag header, and at least one specifies "nofollow" while another does not.Learn moreRobots: noindex differs across specifications
There is more than one source for robots directives, either a robots meta tag or a X-Robots-Tag header, and at least one specifies "noindex" while another does not.Learn moreSafe HTTPS webpage loads unsafe resource
If an HTTPS webpage contains an unsafe resource that is loaded using HTTP, it is flagged with this hint.Learn moreStrict-Transport-Security HTTP header is invalid
If a Strict-Transport-Security HTTP header is not properly defined, the URL is flagged with this hint.Learn moreURL has // in path
If the URL contains two consecutive slashes, it is flagged with this hint.Learn moreURL too long for some browsers
If a URL longer than 2,000 characters is encountered, it is flagged with this hint, since some browsers are unable to handle URLs of this size.Learn moreXML sitemaps: <html:link> is no hreflang link
This hint identifies all XML sitemap files that contain a <xhtml:link> which is not a valid hreflang link.Learn moreXML sitemaps: <lastmod> in the future
This hint identifies all XML sitemap files and XML sitemap index files that contain a <lastmod> definition with a datetime value in the future.Learn moreXML sitemaps: <lastmod> invalid
This hint identifies all XML sitemap files and XML sitemap index files that contain an invalid <lastmod> definition.Learn moreXML sitemaps: URL invalid or empty
This hint identifies all XML sitemap files and XML sitemap index files that contain an invalid or empty URL reference.Learn more
Problem indicating Errors related hints
Linking: Follow link to a so far nofollow URL
A follow link was found, linking to a URL that was previously linked "nofollow" only.Learn moreLinking: nofollow link to a follow URL
A link with rel="nofollow" was found, linking to a URL that was previously linked "follow".Learn moreLinking: nofollow linking revoked later on
A URL that has been linked nofollow has later (i.e. on the same or a deeper level) been linked to as follow.Learn more