Site Inspector

A Ruby Gem to sniff information about a domain's technology and capabilities.

Gem Version Build Status

Demo (source)


Site Inspector involves three primary concepts:

  • Domain - A domain has a host defined by it's TLD + SLD. A domain might be Domain's have certain domain-wide properties like whether it supports non-www requests, or if it enforces HTTPS.

  • Endpoint - Each domain has four endpoints based on whether you make your request with HTTPS or not, and whether you prefix the host with www. or not. So the domain may have endpoints at,,, and There may theoretically be a different server responding to each endpoint, so endpoints have certain endpoint-specific properties, like whether it responds or not, or whether it redirects. Each domain has one canonical (primary) endpoint.

  • Checks - A check is a set of tests performed on an endpoint. A check might look at what headers are returned, what CMS is used, or whether there is a valid HTTPS certificate. There are some built in checks, listed below, or you can define your own. While they're endpoint specific, checks often filter up and inform some of the domain-wide logic (such as if the domain supports HTTPS).



domain = SiteInspector.inspect ""
#  =>  true
#  =>  true
#  => ""
#  =>  { :drupal  =>  {}}

Command line usage

site-inspector inspect -- inspects a domain


  site-inspector inspect <domain> [options]

        -j, --json         JSON encode the output
        -a, --all          return results for all endpoints (defaults to only the canonical endpoint)
            --sniffer      return results for the sniffer check (defaults to all checks unless one or more checks are specified)
            --https        return results for the https check (defaults to all checks unless one or more checks are specified)
            --hsts         return results for the hsts check (defaults to all checks unless one or more checks are specified)
            --headers      return results for the headers check (defaults to all checks unless one or more checks are specified)
            --dns          return results for the dns check (defaults to all checks unless one or more checks are specified)
            --content      return results for the content check (defaults to all checks unless one or more checks are specified)
        -h, --help         Show this message
        -v, --version      Print the name and version
        -t, --trace        Show the full backtrace when an error occurs

What's checked


  • canonical_endpoint - The domain's primary endpoint
  • government - whether the domain is a government domain
  • up - whether any endpoint responds
  • www - whether either www endpoint responds
  • root - whether you can access the domain with www.
  • https - whether HTTPS is supported
  • enforces_https - whether non-htttps endpoints are either down or redirects to https
  • downgrades_https - whether the canonical endpoint redirects to an http endpoint
  • canonically_www - whether non-www requests are redirected to www (or all non-www endpoints are down)
  • canonically_https - whether non-https request are redirected to https (or all http endpoints are down)
  • redirect - whether the domain redirects to an external domain
  • hsts - does the canonical endpoint have HSTS enabled
  • hsts_subdomains - are subdomains included in the HSTS list?
  • hsts_preload_ready - can this domain be added to the HSTS preload list?


  • up - whether the endpoint responds or not
  • timed_out - whether the endpoint times out
  • redirect - whether the endpoint redirects
  • external_redirect - whether the endpoint redirects to another domain


Each endpoint also returns the following checks:


Uses the pa11y CLI to run automated accessibility tests. Requires node. To install pally: [sudo] npm install -g pa11y.

  • section508 - Tests against the Section508 standard
  • wcag2a - Tests against the WCAG2A standard
  • wcag2aa - Tests against the WCAG2AA standard
  • wcag2aaa - Tests against the WCAG2AAA standard


  • doctype - The HTML doctype returned
  • sitemap_xml - Whether the endpoint has a sitemap
  • robots_txt - whether the endpoint has a robots.txt file


  • dnssec - is DNSSEC supported
  • ipv6 - is IPV6 supported
  • cdn - the endpoint's CDN, if any
  • cloud_provider - the endpoint's cloud provider, if any
  • google_apps - whether the domain is using google apps
  • hostname - the server hostname
  • ip - the server IP


  • cookies - does the domain use cookies
  • strict_transport_security - whether STS is enabled
  • content_security_policy - the endpoint's CSP
  • click_jacking_protection - whether an x-frame-options header is sent
  • xss_protection - whether an x-xss-protection header is sent
  • server - the server header
  • secure_cookies - whether the cookies are secure, or not


  • valid - whether the HSTS header is valid
  • max_age - the HSTS max age
  • include_subdomains - whether subdomains are included
  • preload - whether its preloaded
  • enabled - whether HSTS is enabled
  • preload_ready - whether HSTS could be preloaded


  • valid - if the HTTPS response is valid
  • return_code - the HTTPS error, if any


  • cms - the CMS used, if any
  • analytics - the analytics providers used, if any
  • javascript - the javascript libraries used, if any
  • advertising - the advertising providers used, if any

Adding your own check

Checks are special classes that are children of SiteInspector::Endpoint::Check. You can implement your own check like this:

class SiteInspector
  class Endpoint
    class Mention < Check
      def mentions_ben?
        endpoint.content.body =~ /ben/i

This check can then be used as follows:


Checks can call the endpoint object, which, contains the request, response, and other checks. Custom checks are automatically exposed as endpoint methods.


Bootstrapping locally

  1. Clone down the repo
  2. script/bootstrap

Running tests


Development console


How to contribute

  1. Fork the project
  2. Create a new, descriptively named feature branch
  3. Make your changes
  4. Submit a pull request