Decentraleyes: A Local CDN Browser Add-On | NSC #80

Every time you reach out to a website, you are actually reaching out to multiple websites at the same time. Oftentimes, website owners will use Content Delivery Networks (CDNs) to serve resources. They do this to help improve page load time and to eliminate the update cycle for each resource. jQuery, a script that runs on nearly 74% of all websites is a good example of this. Instead of downloading the library, uploading it to your site and repeating every time there is an update, a website owner can simply link to it to ensure that it is always up to date. That’s a terrific concept until you realize who is hosting a few widespread CDNs (we’ll give you a hint, they own Youtube). Decentraleyes is a browser add-on that aims to eliminate reaching out to those resources by serving them locally.


How does Decentraleyes work?

Decentraleyes has a local cache of resources that it uses, in real-time, to replace resources that are usually retrieved from other sites. As a result, pages load faster and your browser isn’t telling third party sites where you are. What this looks like in practice is quite simple and can be verified very easily. In Firefox, open the menu in the top right of the browser, click on Web Developer, then Network (Or Ctrl+Shift+E). After that, Firefox’s network analyzer will open up where you can monitor all your page resources.

For instance, let’s take myrvmail.com, a mail forwarding services for RVers, as an example. While Decentraleyes is disabled, a quick search of the network resources reveals jQuery being loaded from code.jquery.com. If nothing is returned, you may need to reload the page.

Firefox network analyzer with Decentraleyes disabled

With Decentraleyes enabled and a quick reload of the page, searching for JQuery returns nothing. If we click on the Decentraleyes icon in the top right of the browser, we see two resources being served locally: JQuery and AngularJS. Rather than reach out to the internet for these libraries, we are loading these locally.

Firefox network analyzer with Decentraleyes enabled

Why use Decentraleyes?

The two benefits you receive with the Decentraleyes add-on are faster page load times and enhanced privacy. When the resources load straight from your browser instead of from the internet, they will load almost instantly. Enchanced privacy is acheived by eliminating the third party sites your browser has to reach out to. For instance, if you are accessing ajax.googleapis.com from multiple different websites with the same browser on the same IP address, it becomes quite easy for Google to piece together your browser history. Likewise, if your browser isn’t reaching out for resources, there is no opportunity to be tracked by the CDN in the first place. Decentraleyes also claims to remove metadata from requests to CDNs it does not support. Coupling this with uMatrix and Firefox’s block third party cookies option makes it near impossible for third party sites to track you.

Decentraleyes CDN Support

Decentraleyes doesn’t support every resource, but it does support most of the popular ones. Different CDNs can serve the same resources or libraries, but it is up to the site owner to decide which CDN they want to go with. Site owners typically decide based on speed, price and, reliability.


  • Google Hosted Libraries
  • Microsoft Ajax CDN
  • CDNJS (Cloudflare)
  • jQuery CDN (MaxCDN)
  • jsDelivr (MaxCDN)
  • Yandex CDN
  • Baidu CDN
  • Sina Public Resources
  • UpYun Libraries.


  • AngularJS
  • Backbone.js
  • Dojo
  • Ember.js
  • Ext Core
  • jQuery
  • jQuery UI
  • Modernizr
  • MooTools
  • Prototype
  • Scriptaculous
  • SWFObject
  • Underscore.js
  • Web Font Loader.

Questions, Comments, or Concerns?

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