Cloudflare is open-sourcing the BEACON dataset, making billions of anonymized Real User Monitoring (RUM) performance records publicly available on Google BigQuery.

The U.S. Web Design System helps the federal government build fast, accessible, mobile-friendly websites. - uswds/uswds

I will be presenting an all-day Web Performance MasterClass at the WeAreDevelopers World Congress in San Jose, CA from September 23-25, 2026. I have a discount registration codes available if you're interested in attending.

Agentic workflows can hide the cost/quality trade-off rather than remove it, making defects harder to trace back to their source.

CSS text-fit property, background-clip border-area, Focusgroup, and more.

YouTube video by Web Conferences Amsterdam

CSS Day is the conference for CSS designers, developers, spec writers, and browser vendors.

A 10-minute DevTools audit of a top 10k website reveals heavy pages, poor Core Web Vitals, and a preload list that reads like competing team priorities

What has happened with page weight with the adoption of AI?

Using bfcache to plug holes in your site's conversion funnel.

CSS containment lets you isolate layout and paint work to self-contained ‘islands’. Here’s what each contain value does and how to use it safely.

Check your UX Score for free. Real CrUX data across LCP, INP, CLS, TTFB and FCP. Benchmark against the top 300 Dutch websites. No login required.

In a competitive market, page speed is as important as your design and content.

Understand how web performance metrics connect to UX research outcomes.

Web components and CSS custom properties can create a future-proof design system with maximum flexibility

What I learned and did in 2025

When I explain the difference between lab (aka synthetic) and field data to people, one of the things I mention is that the lab allows for testing under repeatable, controlled conditions. Each test ru...

YouTube video by Web Conferences Amsterdam

Image credits: https://commons.wikimedia.org/wiki/File:TAR_Detour_clue.png https://commons.wikimedia.org/wiki/File:Carach_Angren_M%C3%A9an_22_08_200…

On 30th and 31st of October, 2025, the sixth edition of performance.now() will take place in Amsterdam—a single track conference, covering today’s most important web performance insights.

performance.sync() is a meet-up taking place on the evening before the performance.now on Wednesday October 29th! We are looking for speakers! Submit your…

In this episode we have Andrea Verlicchi walking us through some real-world case studies of optimizing INP, and Ethan Gardner will discuss how to make allies...

Join the PerformanceObserver virtual performance meetup to get all the latest web performance news and hang out with the community.

My Journey with AI and how you can get started

YouTube video by JetBrains

Pyenv Wiki Common Build Problems when it was useful - pyenv-common-build-problems-useful.md