There are many tools that you can use, but I think the most basic one is FREIDA:
Looking for the right medical residency? Get started by searching 13,000 medical residency and fellowship programs on the AMA's FREIDA database.
freida.ama-assn.org
There are more tools that you can use with one of them launched last year and that I found really useful:
www.residencyexplorer.org
I am sure there are more search tools that I dont know about, but those 2 are the main ones that I used.