Unsplash has tons of free photos.
PixaBay has Tons of free photos.
Pexels has tons of free photos.
NegativeSpace. Free high-resolution stock photos.
StockSnap.io. Free stock photos
ISO Republic. Free high-resolution stock photos. It has some videos too.
Free Photos. Free stock photos
Stockvault. Nice free stock images.
Burst. by Shopify. Free photos for websites and commercial use.
LifeOfPix. has free high-res photos.
SplitShire. Good selection of free images. There are some videos too.
New Old Stock. Vintage photos, free of copyright. If you need old photos for a project, it’s perfect!
Free Nature Stock.com Beautiful royalty-free nature stock photos and videos
Zoommy is a Paid Mac app to search for images from multiple free sources. I have purchased it, and its search function is mediocre, but sometimes gives you good results.