Dropbox is the more common of the two in our index: it runs on 670 websites against 187 for Cloudinary, and 3 sites use both. Counts come from real scans, not vendor claims.
Cloudinary is an end-to-end image- and video-management solution for websites and mobile apps, covering everything from image and video uploads, storage, manipulations, optimisations to delivery.
3 sites run both Cloudinary and Dropbox. That is 2% of the sites using Cloudinary, the smaller of the two.
Want to know which one a particular site uses? Look it up and see its whole stack, or compare two sites side by side.