Some of the Free Public CDNs for Web Developers

Website speed is crucial for developing the best user experience possible, because, well, no one likes to wait for web pages to load. One of the simplest ways for improving the performance of a site is by serving page dependencies like JavaScript libraries and CSS frameworks via a public content delivery network (CDN). A public CDN is a web service that hosts and serves open source projects used for web development (e.g. jQuery, AngularJS, and Bootstrap). Public CDNs allow websites to use their services for free. Here are the best public CDNs for web development.

With over 1,000 open source projects hosted on jsDelivr, it’s currently one of your most comprehensive options. Similar to Google Hosted Libraries, jsDelivr is an open source CDN that allows developers to host their own projects and anyone to link to our hosted files in their websites.We offer a stable CDN that can be used in production even on popular websites with huge amounts of traffic. There are no bandwidth limits or premium features and its completely free to use by anybody.All kinds of files are allowed, including JavaScript libraries, jQuery plugins, CSS frameworks, fonts and more.You can use this repo to make your own changes and improve the contents of jsDelivr's CDN. Feel free to open issues and pull requests if you think something should be changed.All changes made to this repo are synced to the CDN. It can take a few minutes for the changes to appear on the website.

Another extensive public CDN is cdnjs, which has a little over 900 open source resources conveniently listed all in one page. Tip: See their list of plugins and extensions on GitHub to find useful tools related to the service cdnjs is the repository mirroring all library assets on cdnjs.cloudflare.com. Thomas Davis and Ryan Kirkman created cdnjs, Drew Freyling and Peter Dave Hello are maintainers. Juan Gallardo is our community moderator.cdnjs will host any production version of any JavaScript/CSS library, subject to licence permissions. Beta, release candidate and alpha releases are not usually considered ready for full production status. Requests for pre-release versions of libraries may be declined after peer review.

Many people outside of the ASP.NET development community don’t know that Microsoft has a public CDN. Among the open source projects on Microsoft’s Ajax CDN are jQuery, Bootstrap, and Respond.js. Compared to your other choices, Microsoft’s list of available open source projects is sparse, but what you do get is the peace of mind that comes from using a service maintained by a well-established, 39-year-old tech company.

This CDN is an open source project by MaxCDN and is powered by jsDelivr. The difference between OSSCDN and jsDelivr, besides the user interface and project ownership, is that MaxCDN, which is jsDelivr’s failover/backup CDN, is the primary content delivery network.

Google is a leader in the realm of website speed and performance. But not to be a company satisfied by just talking the talk; they also walk the walk by maintaining a public CDN that hosts popular JavaScript frameworks such as AngularJS, jQuery, and even older ones like MooTools and Prototype.
Project-specific CDNs

Users of BootstrapCDN can load CSS, JavaScript and images remotely, from its servers. Bootstrap uses MaxCDN's global content delivery network, which makes websites using its service resilient to unexpected surges in web traffic

jQuery is a cross-platform JavaScript library designed to simplify the client-side scripting of HTML. Used by over 60% of the 10,000 most visited websites, jQuery is the most popular JavaScript library in use today. jQuery is free, open source software, licensed under the MIT License. jQuery's syntax is designed to make it easier to navigate a document, select DOM elements, create animations, handle events, and develop Ajax applications. jQuery also provides capabilities for developers to create plug-ins on top of the JavaScript library. This enables developers to create abstractions for low-level interaction and animation, advanced effects and high-level, theme-able widgets. The modular approach to the jQuery library allows the creation of powerful dynamic web pages and web applications.The set of jQuery core features—DOM element selections, traversal and manipulation—enabled by its selector engine (named "Sizzle" from v1.3), created a new "programming style", fusing algorithms and DOM-data-structures. This style influenced the architecture of other JavaScript frameworks like YUI v3 and Dojo, later stimulating the creation of the standard Selectors API. Microsoft and Nokia bundle jQuery on their platforms. Microsoft includes it with Visual Studio for use within Microsoft's ASP.NET AJAX framework and ASP.NET MVC Framework while Nokia has integrated it into the Web Run-Time widget development platform. jQuery has also been used in MediaWiki since version 1.16.

The public CDNs in this list are backed by major tech companies, giving you a bit of assurance with regards to their trustworthiness and service performance.

Because public CDNs are used by many websites, there’s a bigger chance that the user coming to your site already has a resource stored in their browser, further improving your page response times.

In my definition of what a "public CDN" is, the service should have no fees and should be accessible by anyone, just like Gmail or Dropbox.