Unsplash - Unsplash is a website with high-quality free HD images. It has a catalog of more than three hundred thousand striking images that are neatly organized with tags. Read more about Unsplash.
Nucleo - Commercial vector icons and accompanying apps to manage and customize them.
Visual Hunt - We hunt free high quality stock photos.
Streamline icons - The world’s largest icon pack library - 100k icons and illustrations.
Pixabay - Over 270,000 free photos, vectors and art illustrations
Freepik - More than a million free vectors, PSD, photos and free icons. Exclusive freebies and all graphic resources that you need for your projects