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Dev4Hub

Free · an AI tutor on every lesson

Learn to code without getting stuck.

Short, ordered lessons in Python, HTML, CSS, JavaScript and SQL — with a browser editor that runs your code in 12 languages and a tutor that answers about the page you are actually reading.

Start with PythonOpen the code editor

No account needed to read a lesson or run code. Sign in when you want your progress, notes and review queue kept.

  • 5CoursesPython, HTML, CSS, JavaScript, SQL
  • 12Languages you can runIn the browser, nothing installed
  • AITutor on every lessonIt reads the page you are on
  • FreeAll of itNo paywall, no trial

Courses

Pick a course and start reading

Each course is one ordered path — a page of explanation, an example you can run, and a short check that you got it. Nothing is locked, and you can jump in anywhere.

Not sure what order to take them in? A roadmap lays out a route and keeps your place in it.

How it works

Read it, run it, and get unstuck without leaving the page

A tutorial you can read is only half of learning. The other half is what happens the moment something does not make sense — and that is the part we built.

The tutor

A tutor that already knows which page you are on

The chat panel follows you down the lesson, so when you ask “why does this line do that?” it already has the section, the example and your history with the topic. No pasting code into a separate tab and explaining the context first.

  • Ask in plain language and get an answer about this lesson, not a generic one
  • It can open the editor with the example loaded, or set you a quick check
  • Save any answer as a note and find it again from the notes drawer
  • The conversation carries across pages, so follow-ups need no re-explaining
Try it on a lesson

The editor

Change the example and run it, right in the browser

Reading an example teaches you less than breaking one. Every code block in a lesson has a “Try it yourself” that drops it into a real editor, so you can change a number, run it again and see what happens.

  • 12 languages, including Python, JavaScript, TypeScript, Java, C++, Go and Bash
  • Nothing to install and nothing to configure
  • Every example in a lesson opens here with one click
  • Ask the tutor about the code you have on screen
Open the code editor
one task, three languages
# the scores so far
scores = [72, 88, 91]
average = sum(scores) / len(scores)

print(f"Average: {average:.1f}")

Output

Average: 83.7

average.pyOpen in the editor

Your progress

A record of what you actually know

Finishing a page is not the same as understanding it. Progress here is measured from what you did — the checks you passed, the ones you retried, the pages you lingered on — and turned into a map of what is solid and what needs another pass.

  • Mastery per skill, built from your quizzes and your time on each page
  • The topics you keep slowing down on, surfaced instead of hidden
  • Spaced-repetition review that brings things back before you forget them
  • Roadmaps that hold the order, so you always know the next step
Look at the skill map
86%62%34%16%

Also included

Everything else, and none of it behind a paywall

The parts that turn a set of tutorials into a way of studying — all free, all in the same account.

Start today

The first lesson is one click away

Open a course and read a page. If something does not land, ask the tutor on that page — that is the whole idea.

Start with PythonBrowse the roadmaps

Free to use. An account only adds saved progress, notes and review.