I've seen this question but it's a few years old and isn't specific to a state.
I am past the inspection stage on a potential new house and the seller wants to use a certain plumber to do some repairs. They forwarded me an estimate and the plumber's address comes up as a residence. I realize that doesn't necessarily mean much, but Googling the business name also yields no results. Does the state of Pennsylvania maintain a searchable online database of licensed contractors in the state, so I can see if this plumber is in fact licensed and insured in PA (specifically, the city of Philadelphia)?