I\'m searching for a tool that would allow me to check whether a certain snippet of HTML would be valid in it\'s proper context.
I\'d input something like
You can actually use the W3C validator to check a snippet.
Choose the 'Validate by Direct Input' tab and select More Options. In there there is a radio button to 'Validate HTML fragment'. http://validator.w3.org/#validate_by_input+with_options
It will wrap your page in valid html so the errors which you see are only due to your snippet.