HTML—the Most Difficult Programming Language in the World

Published on Oct 9, 2025, filed under development, html. (Share this on Mastodon or Bluesky?)

Years ago, the web development community discussed and declared on Twitter that HTML was not just a document language, but a programming language.

Meanwhile, virtually no HTML page is error-free. In HTML parlance, almost no page is conformant, compliant, valid, or “validates.” (Cf. validation data from 2021 through 2025.)

If HTML is a programming language, yet virtually no one writes error-free HTML code, there can be only one conclusion:

HTML is the most difficult programming language in the world.

This is tongue-in-cheek, but the underlying point isn't: If you’re a professional who puts HTML on your resume, ship valid HTML. This is the minimum to be expected of our work, even when our manager or our client doesn’t ask for it. It’s not that hard.

About Me

I’m Jens (long: Jens Oliver Meiert), and I’m a web developer, manager, and author. I’ve been working as a technical lead and engineering manager for companies you’ve never heard of and companies you use every day, I’m an occasional contributor to web standards (like HTML, CSS, WCAG), and I write and review books for O’Reilly and Frontend Dogma.

I love trying things, not only in web development and engineering management, but also in other areas like philosophy. Here on meiert.com I share some of my experiences and views. (I value you being critical, interpreting charitably, and giving feedback.)