A great list of free access images and multimedia repositories (check the licenses).
In fact these are the sources used by the Openverse project (link in our tools directory). With these page you can access these directly when needed for granular search or bulk download.
Openverse is an open-source search engine that aggregates over 800 million Creative Commons-licensed and public domain media files, including images and audio; the source page listed here identifies the specific external repositories indexed by the platform, such as NASA, the Smithsonian Institution, Wikimedia Commons, and iNaturalist.
