Unsplash is a service which provides royalty free images. I've followed Unsplash since its more humble beginnings.
Originally their photos were all under a Creative Commons license, but they switched to their own license for more control. Also, their API offering promotes image downloading versus focusing on finding ways to ensure photographers are credited. To be fair, photographers know they may not be credited if they upload to services like Unsplash. Also, alternatives I provide may not be any better as far as photographer crediting. However, by offering a free API that encourages downloading, large apps integrated with Unsplash tend to allow users to use Unsplash images with no obvious mention of who the photographer is once the image is downloaded or embedded. In fact, one doesn’t know that the image came from Unsplash at all.
The reason I know they promote downloading over photographer promotion is from personal experience.
At another website I manage I created a page which would show a random image from Unsplash's API with a large credit to the Photographer and Unsplash. I did not want to create anything fancy or allow the image to be downloaded. One would think this would be preferred. By not allowing downloads I’m saving their servers bandwidth and I’m helping to ensure the photos and photographers are clearly seen and not just easily downloaded as a profile picture or something with no credits. The website I was adding this to is also small with little traffic. But, I was sent an email stating they turned the API off for my site because it didn’t allow downloads and (paraphrasing) wasn’t fancy enough.
Having said all of this I’m a strong believer in being allowed to do what you want with your website. I’m not as bitter as this post may sound. Unsplash has reasons for what they do, it’s their website/service, and API traffic is expensive if the API is popular. But, I’m also a strong believer in there being alternatives to popular services. Otherwise you start to lean towards monopoly situations and/or web companies may feel empowered to begin doing questionable things because they are the only game in town.
In the spirit of alternatives, personally I’ll be trying out the following services more going forward. I’m not offering recommendations at this time because I haven’t used any of these services enough yet. Instead, I’m simply offering a list.