Youngin’ moving here from Richmond - apps for housing/finding roommates

To make a long story short, I’ve lived in Nova for a decade (Arlington and Alexandria) but am at a loss in providing advice to a young friend looking to move to Arlington. He is coming from Richmond and doesn’t know where to start. I could generally advise about where to live based on my old guy knowledge when I lived in Virginia square in my early 20s, but I really don’t know how you would go about finding a place now. He is looking to move in with people and be relatively close to the action. Isn’t there some type of apps the young kids must be using these days for this sort of thing? Any help would be appreciated!