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SEOInfo displays icon alerts as you navigate website pages for SEO errors. At the click of a button, all SEO and performance information and graphs about the current page are displayed. Includes SEO checks, Structured data and AMP validation inside the extension. This information can be saved with a single click to another tab for printing or saving to file.


SEOInfo is currently available in English, Spanish and French. Languages are built-in and should be picked up automatically from your browser upon installing the extension.


The extension icon changes to tell you if the current page is ok or has errors or warnings. Clicking the extension icon provides you with all the details, as follow:

Page content

SEOInfo main popup screenshot

  • Page title, description, canonical
  • Accurate Google search results preview with title truncating by pixel, breadcrumb and publication date representation based on JSON-LD structured data
  • Page can be indexed, followed - applying robots.txt content
  • Page is mobile-compatible
  • Chain of server-side redirects to load the page
  • All server response headers
  • Server IP and HTTP protocol version used
  • All OGP and Twitter Cards tags
  • All other meta tags and links tag
  • All JSON-LD structured data tags
  • All microdata structured data
  • Page uses a service worker
  • Save links and resources list to an Excel file

Background checks:

  • Canonical: full automatic validation of the canonical link, ie not an error, not blocked by meta or robots.txt and not a redirect loop
  • HrefLang: full automatic validation (see below)
  • Web Vitals: automatic scoring (on supporting browsers)

Structured Data

SEOInfo Structured data validation screenshot

Structured data are validated using Google public structured data validator. After opening the extension popup, go to the Struct. data tab and click the Validate button. After a few seconds, validation results will be displayed, including the full display of structured data found on the page and detailed error descriptions if any.

Json-ld and microdata found in the page are parsed, displayed on a separate tab and used in Google Search preview.

Page Audit

SEOInfo page full audit screenshot

At the click of a button, SEOInfo will use the Page Speed Insight API to perform a full audit of your page. Audit can be done either for the desktop or mobile version of the page.

SEOInfo uses the full API, not just the Performance section which is what you get using the online Google tool. You will get audit on:

  • Performance
  • Accessibility
  • Best Practices
  • SEO
  • Progressive Web App

For each section, you will get the full detailed report on each error or improvement opportunity. Here is an example from an Accessibility report:

SEOInfo example of accessibility report error screenshot

SEOInfo links validation screenshot

  • Display all links found in a page with:
  • total count
  • total internal
  • total external
  • total follow/no Follow
  • total non-http (ie javascript, tel, skype, etc)

Upon click of a button

For each link found in page:

  • HTTP status
  • Invalid links
  • List can be filtered by status

Note: as there might be a high number of links to check on each page, the verification process is throttled so that requests are made to each domain at a rate of 2req/sec on average with bursts of maximum 3 req/sec.

Full list of links with their status can be saved as an Excel file.


SEOInfo hreflang validation screenshot

  • Displays all HRefLang link tags found in head section
  • Validation against Google HrefLang specification:

  • Validate that each link is fully qualified, including transport method.

  • Validate language code against iso639-1
  • Validate country code against iso3266-1 alpha 2
  • Validate language script variations against iso15924
  • Check language codes with multiple entries
  • Check for multiple x-default entries
  • Check for meta robots blocking current page
  • Check for robots.txt blocking current page
  • Display language and country or script variation in plain text for verification
  • Check that page is canonical

Background checks:

On all pages linked with hreflang tags:

  • All hreflangs must be present
  • Language code and country/script variations checks
  • Check for multiple entries
  • Check for meta robots blocking
  • Check for robots.txt blocking
  • Check that page is canonical


SEOInfo main popup screenshot

  • Performance: TTFB, Interactive, Load times, transfer sizes for page and assets (images, fonts, css, javascript, ...)
  • On supporting browsers: First Paint and First Contentful Paint
  • On supporting browsers: Web Vitals scoring and icon alert
  • Performance and resources sizes displayed in table and as graphs

Response details

  • Server IP address
  • Server protocol (ie HTTP/2, HTTP 1.1, etc)
  • All server response headers

Accelerated Mobile Pages

SEOInfo example of AMP validation errors screenshot

  • AMP status: has an AMP version? is this an AMP page? does it have errors?
  • If a page as an AMP version, the AMP version is validated in the background so you do not need to visit it
  • Is the AMP version stored in Google AMP cache?
  • If not AMP cache, add it with a single click

Due to restrictions from Mozilla add-ons store, and from version 1.3.0, all AMP-related features have been removed from the Firefox version of SEOInfo.

Background checks:

  • AMP pages: full validation. Errors and warnings are displayed in the extension

Resources loading and errors

SEOInfo resources loading information screenshot

  • List of all assets loaded, with error/success status, from server/from cache status and indexability (check against meta robots and robots.txt file)

SEOInfo resources errors information screenshot

  • List of resources errors including HTTP status and indexability
  • List of assets can be saved to an Excel file with their status, size and load time

Background checks:

  • load status of all resources (OK, 404, 403, etc)
  • indexable and followable status for all resources

Saving information

  • The entire report can be saved in a different tab with a single-click and then printed or saved to a file.
  • You can include a screenshot in the saved report, or just do a screenshot

SEOInfo saving information screenshot