The tesseract gif on the home page was found on bing.com image search, and the source is laetusinpraesens.org.

The tetrahedron and octahedron images on the similarities page were both found on bing.com image search, their sources are d138zd1ktt9iqe .cloudfront.net for the tetrahedron and www.mathsisfun.com for the octahedron

The cube, dodecahedron, and icosahedron images on the similarities page are all from wikipedia, their links are below.

The gifs on the similarities page are all from wikipedia, links below.

The gif on the prisms page is from wikipedia, link below.

The image on the chirality page is from wikipedia, link below.

All this information is coming off the top of my head, with the exception of the information on honeycombs, which I got from google AI and fact-checked on wikipedia's honeycomb sections in its list of polygons,polyhedra,and polytopes.