On one 4-bed you'd typically be looking at a small stack rather than one product. Property management software handles the leases and rent collection, and the common tier for a handful of doors runs from free with per-transaction fees up to roughly 30 to 60 dollars a month. Listing sites that let you advertise a single room rather than a whole house often charge per listing or per lead, so plan on a marketing cost each time you fill a room instead of a flat monthly fee. Tenant screening, meaning the credit and background check, is usually charged per applicant, commonly somewhere in the 30 to 50 dollar range, and in a room rental you screen more applicants than you would on a whole-house lease.
Roommate matching is a feature of some larger co-living platforms rather than a thing most small operators buy. On four rooms, most people do that themselves by asking about work schedules and smoking.
One term to keep straight: per-room rental means each tenant signs their own lease for their own bedroom. A single lease signed by four housemates together is a joint lease, and it's a different arrangement even though people call both of them room rentals.
Spreadsheet and a payment app does work at four rooms. What it doesn't give you is a dated record of who paid what and when, which matters a great deal if you ever have to remove one tenant while three others keep living there. That's the reason most operators move onto software earlier here than they would with a single lease.
