Midudev's intro to a free OpenAI Codex course: 22 lessons in 3.5 hours, but what's inside?
A faithful rundown of the free OpenAI Codex course introduced by developer midudev: 22 lessons across 3.5 hours, a build-and-iterate flow for webs and apps, ski
Developer Miguel Ángel Durán (@midudev) introduced a free OpenAI Codex course in an X post dated October 8, 2026 (UTC). According to that post, the course covers building and iterating on webs and apps, with 22 lessons, a 3.5-hour runtime, no card required, and English with subtitles. Those lesson-count, duration, and curriculum claims come from this single introducing post and have not been independently corroborated.
Image source: image attached to the @midudev X post / master.dev course page
The course outline, exactly as the author wrote it
The original post (in Spanish) reads: "OpenAI ha publicado un curso gratis de Codex. Te explica cómo desarrollar e iterar webs y apps." Its checklist continues with "22 lecciones. 3,5 horas. Sin tarjeta" and "Skills, plugins y feedback visual para iterar menos." On language, it adds "En inglés pero con subtítulos," and links to the course page at master.dev (https://master.dev/courses/codex/).
The practically interesting line is the last one: it groups skills, plugins, and visual feedback as the way to iterate less. The post carries one attached photo, but the factual scope of this article stays with the text claims.
Two usage suggestions from the replies, kept separate
These are commenters' opinions, not course content, so read them apart from the author's claims.
- @camiloarizaf's suggestion: visual feedback changes the frontend loop most because the agent sees the render instead of guessing from code; pairing the course with Playwright tests leaves each iteration verified rather than merely "looking good."
- @IArtesanoX's suggestion: bring an existing project plus one small improvement to the course, so that fixing it without breaking prior work forces code understanding, change review, and testing — a course pays off more when you can maintain what you built.
Neither suggestion is an official description of the course curriculum.
How to consume this introduction
This article is a translation and faithful rundown of an introduction post, not a course review. The five conditions — 22 lessons, 3.5 hours, no card, English with subtitles, and skills plus plugins plus visual feedback — all trace to @midudev's single post. Before enrolling, check the lesson list, runtime, and enrollment terms on the course page itself.
Original source
- Original post by Miguel Ángel Durán (@midudev): Free OpenAI Codex course introduction
- Course page: https://master.dev/courses/codex/