Website Speed Test — Website speed test with a focus on image loading times.
BucketListly Photos — Creative commons photos tagged by country.
Compressor.io — Optimize and compress your images and photos.
DesignersPics — Free high-res photos for use.
FreePhotos.cc — Free stock and royalty-free images.
Gratisography — High-resolution photographs.
Pexels Photos — Free stock photos - public domain and CC.
PicApp — App image generator.
Pixeden — Free designer graphics.
Pixlr.com — Online photo editor.
Public Domain Images Archive — Free public domain stock photos.
Skuawk — Curated public domain photos.
Stock Up — 15,000+ indexed photos from over 30 different stock photography sites.
Superfamous — Stock landscape photos with a CC license.
The Pattern Library — Free pattern images.
TinyPNG — Compress PNG images while preserving transparency.
Unsplash — High-resolution photos.
Vastpic — Free high-res photos.
VisualHunt — Free high-quality stock photos from many different sites.
XnView — Easy-to-use photo viewer, organizer and converter.