A simple extension to list all the meta tags used on a webpage
Read all about it: http://blog.staginginstance.com/creating-first-chrome-extension-show-meta-tags-used-webpage-5-easy-steps/
Download the extension here: https://chrome.google.com/webstore/detail/meta-tags-seo-tool/miihmfdpfdioogfbfofbnagblnjbjomg