Freeimages

Searchable high-resolution photos. Provide suggestions for iStock ...

iStock

Good selection of stock images, both photos and illustrations

Pexels

Pexels provides high quality and completely free stock photos ...

PhotoDune

Part of Envato Market. Offers low price stock photos and some free ones too each month.

Pixabay

Pixabay is a vibrant community of creatives, sharing copyright free images and videos.

Unsplash

Directory of high quality photos (that don’t resemble generic stock images) offered for completely free use