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* **[WAI-Aria](http://www.w3.org/TR/wai-aria/):** use WAI-Aria tags to help machines understanding your code
* **[RichSnippets](http://schema.org/):** markup your code with rich snippets, they show up on the search results page
* **[Custom Search](https://developers.google.com/structured-data/slsb-overview):** with sitelink Google Sitelink search box, people can reach your content more quickly
* **[nofollow](https://support.google.com/webmasters/answer/96569):** add `rel="nofollow"` attribute to external links only to prevent spam and bad links
* **[mobile friendly](http://googlewebmastercentral.blogspot.be/2014/11/helping-users-find-mobile-friendly-pages.html):** mobile optimized sites are marked in search results. Test for [mobile friendly site](https://www.google.com/webmasters/tools/mobile-friendly/)
* **[AppLinks](http://applinks.org/documentation/):** apps that link to your content can then use this metadata to deep-link into your app
* **[Tap targets](https://developers.google.com/speed/docs/insights/SizeTapTargetsAppropriately):** clickable links should not be too small
* **[Smart App Banner](https://developer.apple.com/library/ios/documentation/AppleApplications/Reference/SafariWebContent/PromotingAppswithAppBanners/PromotingAppswithAppBanners.html):** Safari has a Smart App Banner feature that provides a standardized method of promoting apps on the App Store from a website.
* **[Social Profiles](https://developers.google.com/webmasters/structured-data/customize/social-profiles):** add social profiles to your Google search results
* **[Google Search Console (GWT)](https://www.google.com/webmasters/):** allows webmasters to check indexing status and optimize visibility ot their websites
* **[PageSpeed Insights](https://developers.google.com/speed/pagespeed/insights/):** Page Speed Insights measures the performance of a page for mobile devices and desktop devices.
* **[feedthebot seo tool](http://www.feedthebot.com/tools/):** displays: domain strength, links, image seo, social counts & mentions, page/technical seo, pagespeed and more.
* **[Webpagetest.org](http://www.webpagetest.org/):** Web Page Test gives you an overall performance waterfall as well as rendering timeline for sites. It also provides critical insight into time to first byte and what could be holding back web page performance
* **[AdWords Keyword Tool](https://adwords.google.com/KeywordPlanner):** plan your Search Network campaigns and learn what your customers are looking for
* **[Google Trends](http://www.google.com/trends/):** explore Google trending search topics with Google Trends.
### Structured Data
* **[Google+ Snippet Creator](https://developers.google.com/+/web/snippet/):** customize the snippet people see when your page is shared.
* **[Structured Data Testing Tool](https://developers.google.com/structured-data/testing-tool/):** past in you rich snippets or url to test it
* **[Twitter card validator](https://cards-dev.twitter.com/validator):** Enter the URL of the page with the meta tags to validate
* **[Facebook Debugger](https://developers.facebook.com/tools/debug):** Enter the URL you want to scrape to see how the page's markup appears to Facebook.
* **[OuiSEO](https://github.com/carlsednaoui/seo-bookmarklet):** An open-source bookmarklet that shows you on-page SEO and social meta data information.
* **[SEO Bookmarklet](http://twkm.ca/projects/seo-bookmarklet):** A One-Stop SEO Bookmarklet to Quickly Review On-Site SEO