What LocalCDN actually does
LocalCDN emulates popular CDNs in your browser. When a page tries to load a supported library (e.g., jQuery, Bootstrap) from a third-party CDN, LocalCDN intercepts the request and provides a local copy packaged with the extension. The page works the same—but your browser makes zero requests to that third-party host.
Why this matters
- Privacy: Fewer off-origin requests → less cross-site profiling via CDN logs.
- Speed: Local file → instant, no DNS/handshake/latency.
- Resilience: If a CDN is slow or blocked, the page can still run.
How it looks in the wild
- Site requests https://cdnjs.cloudflare.com/.../jquery.min.js
- LocalCDN recognizes it and serves a matching local copy.
- No network hit to cdnjs/Google/StackPath; functionality unchanged.
When to use it (and when not)
Great fit
- You browse with uBlock Origin and want fewer exceptions.
- You value privacy and prefer fewer third-party dependencies.
- You’re on flaky networks where CDNs sometimes stall or are blocked.
Know the limits
- It only replaces supported library URLs (not every asset on the web).
- New library versions may appear before LocalCDN ships them.
- On Chromium, a few extension APIs are more limited than Firefox.
Rule of thumb: LocalCDN is a great user-side safety net. If you’re a site owner, the gold standard is still to self-host your own JS/CSS/fonts and avoid third-party CDNs entirely.
How to install
- Firefox: Get LocalCDN from the official add-ons store.
- Chromium-based: Install from the Chrome Web Store (works; a few features are Firefox-only).
After install, it works automatically—no setup needed.
Recommended settings
- Pair with uBlock Origin: Let uBO handle network-level blocking; let LocalCDN swap safe library URLs locally.
- Be cautious with font blocking: If you block remote fonts, allow only what you need or prefer sites that self-host fonts.
- Keep it updated: New versions add more libraries and fixes.
Verify it’s working (no tracking needed)
- Open your browser’s DevTools → Network.
- Visit a site that loads common libraries from a CDN.
- Look for requests to cdnjs.cloudflare.com, ajax.googleapis.com, etc. With LocalCDN active, those should be missing (or show as served locally by the extension).
LocalCDN also offers a simple testing page; if you prefer, use that to confirm replacements without digging into DevTools.
FAQ
Isn’t this what Decentraleyes did?
Yes—LocalCDN began as a fork, expanded the number of supported libraries, and continues active development.
Will it break sites?
Rarely. If a site pins a very specific version that LocalCDN doesn’t have yet, it’ll just load the normal remote file. If you’ve set aggressive “block if missing” options, loosen them for that site.
Do I still need a content blocker?
Yes. LocalCDN isn’t an ad/tracker blocker. Use it with uBlock Origin for best results.
For site owners: the sovereign approach
- Self-host your JS/CSS/fonts on your own origin; avoid cross-origin CDNs.
- Pin versions intentionally; don’t auto-pull latest from a CDN.
- Measure: Use your on-page badge (no beacons) to prove zero third-party requests.
LocalCDN helps users; your job as a site owner is to make it unnecessary.
Get LocalCDN
- localcdn.org — overview & tutorial
- Firefox Add-ons
- Chrome Web Store
Disclosure: This site isn’t affiliated with LocalCDN. All trademarks belong to their owners.