Hi I’m Felix!

Web Engineer / WordPress Core Committer / Consultant at Yoast

  • WordPress Core Committer
  • Plugin Developer
  • Conference Speaker
  • Multisite & REST API Maintainer
  • Community Member
  • World Traveller
  • Blogger

I’m @flixos90 on wordpress.org and @felixarntz elsewhere.

Projects I have contributed to

Latest Posts

This Site is now AMPenberg

Category: September 12, 2018


Category: , June 24, 2018

Using the WordPress Test Suite

Category: August 22, 2017

Core Contributions

I have been a WordPress Core Contributor since version 4.3 which was released in August 2015. I’m currently a component maintainer of the Multisite component and the REST API component, but regularly work in other areas as well. With WordPress version 4.6 I became one of the “Recent Rockstar” developers for the first time, and since November 2016 I have been a Core Committer.

Over the course of time I have opened 169 tickets, received 144 props and made 111 commits. Working on WordPress Core and other open-source projects is a high priority for me, so I ensure I have work time available to dedicate to it, and I am always interested in opportunities to get sponsored.

Consultant at Yoast

Since early 2018, I have been working part-time for Yoast, who I have always admired and regarded as one of the very top companies in the WordPress space. They have an agenda that I can truly align with, a crazy-successful product, solid developers who are constantly improving, and a wonderful team that I am grateful to be part of, after having been friends with some of them for quite a while.

Not to forget, Yoast also give back to open-source a ton, they are the company that sponsored most WordPress core committers in recent years. As such, they enable me as well to spend a significant amount of my time contributing to WordPress core, in addition to helping with their SEO plugin (which of course is open-source too).

GitHub Projects


A JavaScript-based cache solution for WordPress using the client’s local storage or, as fallback, a simple variable storage.

Language: JavaScript Stars: 23


Object cache implementation for WordPress that acts as an adapter for PSR-6 and PSR-16 caching libraries.

Language: PHP License: GPL-2.0 Stars: 18


An OOP library to register admin pages in a sane way. Focused on WordPress, but easily reusable in any other environment.

Language: PHP License: GPL-2.0 Stars: 7

WordPress Plugins

Bootstrap for Contact Form 7

This plugin modifies the output of the popular Contact Form 7 plugin to be styled in compliance with themes using the Bootstrap CSS framework.

40,000+ installs Rated 96 / 100

WP Encrypt

Generate and manage SSL certificates for your WordPress sites for free with this Let's Encrypt client.

10,000+ installs Rated 82 / 100

Plugin Name: Responsive Video Shortcodes

This tiny plugin allows you to embed online video from YouTube, Vimeo and more media…

2,000+ installs Rated 90 / 100