UPDATED: November 27, 2017
When I originally published this post nearly 6 years ago, it was much more difficult to find images that could be used for free, for any purpose, including commercially. Since that time, much has changed. There are a plethora of sites that offer CC0 or public domain photos now, so it’s long past time for me to update this post. Although I could probably list about 25 good free stock photo sites here, there is really very little purpose in doing so. Instead, you deserve to know about only the best, most comprehensive sites available. When you need an image, you don’t want to spend time on 25 sites trying to find the right one. You want to search one or two sites, knowing that they will have what you need. So below you’ll find 4 sites in 3 categories, and yes, one of them isn’t free. That’s because there are times when the free sites, no matter how extensive they might be, just don’t have that one image you are looking for. 9 times out of 10, the paid site will. So I include it here because I actually end up using it fairly often, and you probably will too. Enough talk. Let’s get to the images!
The 2 Best CC0 and Public Domain Free Image Mega-Search Sites

Pexels is definitely my favorite source for free stock photos. The images are presented beautifully, and along with having various image sizes available to download, Pexels also gives the option to download a custom size. Just enter the height and width you need, and that’s what you’ll get. Great timesaver! I also like the fact that each image lists the source of the original image. Since this is a mega-search site, it pulls in CC0 images from many other, usually much smaller, free image sites, such as the popular Unsplash. I like knowing that others are getting credit for their efforts.

Pixabay is also an excellent source for free stock photos. I find what I need here probably 75% of the time. It’s well laid-out, has a good selection of photos for most topics, and offers various sizes to download. It lacks the excellent option to download a custom-sized image, so it falls behind Pexels in that regard. Otherwise, it is a solid choice.
Best Unique Free Image Site
You’ll find that many of the free image sites have mostly the same free images as every other site. That may end up being true of this next site as well in the future, but at least for the moment, it has a lot of images that I don’t see everywhere else (approximately 1/3 of the 60,000+ images on the site are currently exclusive to Pikwizard). For that reason, plus the fact that it’s got a very nice interface, Pikwizard joins my list of favorites. You’ll find both CC0 and “free licensing” images. Free licensing images are free to use, but the photographer retains the copyright. You can read more about the difference here.
Best Free Transparent PNG Image Site

Sometimes, you just need an image with a transparent background. Maybe you are creating your own graphic, and need to place an ice cream cone on it, for example. I bring this up because this was exactly what I needed to do yesterday for another site I was working on. Sure, you can download a photo of an ice cream cone, but then you’ll need to do all the work of cutting out the background, and hoping the edges of the cone look sharp and well-defined. Or, better yet, you could cross your fingers and hope to find an image of an ice cream cone that has a transparent background. The best place to find that is at PNGIMG.