It's not my tool, but just discovered this and I think it can be very useful. Detects common problems and also checks for things like duplicate CSS selectors and heavy Javascript use.
Besides this hosted version there are other options available, including a commandline client and an API. Check the GitHub repo [1].
Besides this hosted version there are other options available, including a commandline client and an API. Check the GitHub repo [1].
[1] https://github.com/gmetais/YellowLabTools