Free Image databse, behind website

I am working on a University project. I have developed a test harness, one of the features of the test harness is visual regression testing.

I am developing a basic website, as a means to displays these generated images programmatically.

My original idea was to use a mongodb database, however after some reading many people advise not using mongodb to store images.

I then tried to use google drive and drop box, however they do not facilitate permanent url's to the stored images. Or in the case of dropbox, these urls are random so not programmatic.

I need to find a way to store these images, programmatically store them using a nodeJS script, programmatically access them using JS.

Any ideas?