PerfMatters: From Idea to Launch

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The trigger was a blog post by Stoyan Stefanov: AISlow. His idea: feed Lighthouse data through an ML model and explain it with GPT in plain language.

I wanted to try this.

The result is PerfMatters – a tool that analyzes web performance, predicts the SpeedIndex, and explains in plain language what makes a page slow.

The stack:

  • LightGBM for prediction (R² = 0.90)
  • SHAP for feature importance
  • GPT-4o-mini for the summary
  • Laravel + FastAPI

Stoyan tested it right away and found a few edge cases – now fixed. Thanks for that!

→ perfmatters.com

OpenPIMS: Looking Back at 6 Months Prototype Fund

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Six months of Prototype Fund, for the second time. The project: OpenPIMS – abolishing cookie banners through centralized consent management.

This project was funded as a private individual through the Prototype Fund.

The Goal

With TDDDG §26, there is finally a legal framework for PIMS in Germany. OpenPIMS was meant to provide this infrastructure: Set once centrally, apply everywhere.

What Was Built

  • 3-tier consent system – by category, provider, or individual cookie
  • Browser extensions – Chrome, Firefox, Safari, Edge (unified codebase)
  • Privacy proxy – Python mitmproxy addon + Cloudflare Worker
  • Magic link login – No passwords, deterministic tokens

The Problem

Technically it works. But: Chicken-egg problem. Without websites, there is no benefit for users. Without users, there is no incentive for websites.

Status

OpenPIMS is on hold. The code is on GitHub. Focus is now on PrivacyProxy and TrialCode.

Sometimes pausing is the right decision.