Unsplash
When you need a quality photo, but can't afford to pay photo a photographer, or just need a placeholder for some design, Unsplash (https://unsplash.com/) is for you. It provides open source and free-to-use images uploaded by photographers:
Unsplash (https://unsplash.com/)
I use it every day, and, to be honest, it became one of the websites I use the most.