Baseline Polyfill CDN+

A smart CDN that delivers only the polyfills your target Baseline Year actually needs, making websites faster, lighter, and future-proof.

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Inspiration

As developers, we’ve all faced one major pain: adding huge polyfill bundles just to support older browsers. These files slow down load times and bloat modern web apps, even when most users don’t need them anymore.
We wanted a smarter way: a polyfill CDN that understands web evolution.

What it does

Baseline Polyfill CDN+ automatically delivers only the polyfills required for a selected Baseline Year. It’s like the web’s time machine, you pick your target (e.g., 2024, 2025, 2026), and it dynamically serves exactly what browsers from that year would need.

Developers can preview, test, and embed the generated script directly in their projects.

How we built it

  • Frontend: HTML + Tailwind CSS for a clean, fluid, responsive dashboard UI.
  • Backend: Node.js (Express) to serve dynamic polyfill scripts.
  • Polyfills: Powered by core-js and polyfill.io CDN, loaded only when needed.
  • Live Preview: Embedded <iframe> runs real-time polyfill demos for instant verification.

Challenges we ran into

  • Mapping Baseline compatibility data to feature support was tricky; we had to create a custom dataset for testing.
  • Making the demo update dynamically without a full reload required careful DOM scripting and isolation.
  • Ensuring polyfills were loaded asynchronously and didn’t break native features took a lot of iteration.

Accomplishments we’re proud of

  • A fully working, real-time Baseline-aware polyfill generator.
  • Fast, modular backend that can scale with more features.
  • A clean, intuitive frontend that impresses on first look.
  • All code is structured and documented for open-source collaboration.

What we learned

  • The power of the new Web Baseline initiative.
  • The importance of balancing modern web performance with backward compatibility.
  • How to build a developer tool that’s both functional and presentation-ready.

What’s next

  • Integrate automatic browser detection for runtime polyfill decisions.
  • Add performance insights comparing baseline vs non-baseline bundles.
  • Launch as a free developer tool, "The smarter way to load polyfills."

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