W3CV - W3C Validator CLI
How can this tool help?
I often have to validate pages locally which are not accessible publicly on the internet (eg. http://wptest.dev). I know there are browser extensions and other tools. However I was convinced, I didn't need a feature rich swiss army knife. I just needed a tool that can fetch a webpage, validate it and give me the results. I built it to do a very specific task.
How to use it?
php w3cv.phar http://example.com
Yes, use the phar file. You can also make it executable and put it in your path for more fancy workflow.