SEO Minion

While I will go into my own specific search including examples, features, and recommendations.  They do a pretty good job explaining it in their own video which I will post below:

Things that SEO Minion will allow you to do straight from your browser:

• Analyze On-Page SEO which includes: Title, description, Headers, images, and much more!
• It also allows you to Highlight all links
• Check for broken links
• SERP location checker
• Also a SERP previewer

This is a pretty straightforward extension and pretty easy to learn.  I would say most people can use it straight away after setup.  Simply go to a page you want to check and click the little Minion on the extension bar and click the option you are looking for.

I would recommend trying it out and seeing if it is a good fit for you!  Personally, it does a lot for an extension, and would not be surprised if it doesn't eventually start charging as Chrome extensions seem to be very popular amongst the SEO community!