Alt Tag Checker

Hi Dominique,

I was wondering if you know if a software or program that will scan through my whole website and produce a list of images that don't have alt tags? I'm trying to fix all the messiness of the person who was in charge before me and don't particularly fancy manually crawling through the whole site looking for missing alt tags.

Any light you could spread on the situation would be great.

Thanks, 
Chloe