Included here are some of the businesses that provides a quick way to fetch your project resources.
cdnjs
CDN for web-related libraries.
Cloudinary
Mostly images and video CDN; also has image and video manipulation.
Staticaly
CDN that serves files from different repo (BitBucket, GitLab, GitHub, and even GitHub gists) with the proper headers.
UploadCare
Image CDN with image manipulation on-the-fly.
Freebies Hunt is a programmer-oriented and a personal resource list gathered by @foo-dogsquared after having a stroke with open content enthusiasm. This'll help you in finding quality free (and open source) resources to get started doing on your projects (or learnings).
Freebies Hunt is also an open source website which you can see the source code for it right here. Of course, feedbacks and contributions are welcome! 🤗
If you are looking for an API of this site (for some reason) to get its data, you're in luck! It's available as an npm package. You could also see the source code of it in this remote repo.
Personal comment:
If you're looking for web dev't libraries, I recommend you find it here. Most of the popular libraries and frameworks are hosted here.