CodeTrain never writes the code for you. Pick a course or paste any public repo, and it builds a hands-on lesson out of what is actually in there. You type every line, it reviews what you wrote, and a step has to run before the next one opens.
Ten lessons a month on the free plan, no card. There is also a free open-source skill you can run on your own machine, where your code never leaves it.
Ramping a team rather than yourself? Start on the team page instead.
Two steps, about a minute, and the first one is going to catch you. Everything here runs for real in your browser. The tutor's replies are pre-recorded, so it knows the handful of ways this lesson usually goes wrong. The real one reads whatever you actually wrote, and it is free for ten lessons a month.
This lesson needs JavaScript to run. With it on, you get a real editor and a Run button right here. You can also run the open-source skill locally instead.
Everything below is a curated course, written by hand so there is somewhere to start. It is laid out like a transit map: a course is a line, each class is a stop along it, and every class is hands-on lessons where you write each small step yourself. You are not limited to this list. Ask for any topic and CodeTrain writes the lesson on the spot, paste any public repo and it teaches you that codebase, or on Pro point it at your own private checkout.
Nothing matches that. Clear the filter, or start free and ask for any topic.
Reading an explanation feels like learning. Producing the code is learning. The whole design is built around making you do the second one.
Ask it to write the function and it will not, no matter how you phrase the request. Stuck learners get a smaller step or the next hint instead. The full rule set is published here, quoted from the prompt it actually runs under.
You write the line in a real editor and hit Run. Python and JavaScript execute in your browser; bash runs in a sandbox. If it does not pass, the lesson does not advance, so you can never finish something you cannot actually do.
Paste a repository URL and say what you want to understand. The lesson is built from the code that is in there today, not from a course someone recorded two years ago. Secrets and gitignored files are refused before they are read.
The concepts you fumbled are scheduled to return at widening intervals. One click turns a due concept into a fresh drill built from your actual mistake, not a replay of the lesson you already sat through.
Start free, no card. Upgrade when you want your own private repos or your own model key.
Ramping a whole team rather than yourself? There is a version of this page for that, with seats, a progress dashboard and per-seat budgets.
No, and it is the one rule it will not bend. The tutor's own instructions say the learner writes every line and that it must never write or paste their solution, not even a single line. The full rule set is published here.
The opposite. Explainers do the work for you. CodeTrain makes you write every line, reviews it Socratically, runs it, and schedules the concepts you did not get to come back as a fresh drill days later. You finish able to do it without help.
Opposite jobs. Those exist to produce code faster and they are good at it. CodeTrain exists so you can still explain and change that code in six weeks. Most people should run both. Where each one fits, including when not to use us.
Two ways. The free downloadable agent runs on your machine and reads your local checkout, so nothing leaves it. On Pro, repo mode runs against your own checkout on 127.0.0.1 and edits land in your real branch. On the free managed tier you can point it at any public repo URL.
Curated courses cover Python, JavaScript, bash and the maths behind LLMs in pure NumPy. Repo mode is not limited to that list: the lesson is built from whatever is in the code you point it at. Browse every course.
Yes, two of them. The managed tutor is free for ten lessons a month with no card, and the core tutor is a free, open skill you can run today and keep forever.
Pick a course or paste a repo you have always meant to understand. Free to start, no card.