Adding to the list: Pixels<p>[3] <a href="https:&#x2F;&#x2F;www.pexels.com" rel="nofollow">https:&#x2F;&#x2F;www.pexels.com</a><p>[4] <a href="https:&#x2F;&#x2F;www.pexels.com&#x2F;photo-license&#x2F;" rel="nofollow">https:&#x2F;&#x2F;www.pexels.com&#x2F;photo-license&#x2F;</a><p>They currently have over 5000 photos (~600 new images are added every month)