Use pxhere.com to find images and stock photos free of copyrights under a CC0 license.
CC Search is a tool that allows you to browse images, audio and video that can be reused.
oaFindr was a curated open access discovery platform. Now the name has changed to 1findr and it aims to index articles in all peer-reviewed journals, in all fields of research, in all languages. So both paywalled and Open Access articles are indexed, but you can refine your results by Access Type (Open Access or Paid/Subscription).
The 1findr institutional edition is available to Max Planck researchers at:
NOA is a search engine for scientific images from open access publications. It is based on automatic harvesting and indexing of figures from the fields of engineering and technology. NOA is using the infrastructure of Wikimedia Commons and Wikidata.
With its constantly growing index, oaFindr is the world’s largest curated open access discovery platform, offering access to more than 25 million articles published in peer-reviewed journals.
The full oaFindr collection is now available to Max Planck researchers at: https://oafindr.1science.com/