The DOM Monster is a cross-platform, cross-browser bookmarklet that will analyze the DOM & other features of the page you’re on, and give you its bill of health. It also works great on mobile browsers!
You’ll get helpful hints and tips about things like:
- Average node nesting depth, and if it’s too high
- Total size for the HTML on the page (even after ajax calls, etc)
- Use of deprecated elements
- Empty and comment nodes
- …and many more!
The best thing: the DOM Monster is free and open source (MIT license). Contribute your own tips and tests. Visit the DOM Monster repository on GitHub to fork and contribute!