CodeTrain teaches your developers on their own codebase, one small step at a time. They type every line themselves and every step has to run and pass, so you get proof of what actually stuck, not a completion percentage.
The free skill: your code never leaves your machine, grab it on GitHub. Pro (from $24/mo) adds a managed tutor that works differently, here's exactly what it sends.
AI can write the code. It can just as easily take a team off the rails.
CodeTrain keeps your engineers on the tracks: they understand what they ship, and you can prove it.
CodeTrain is a Socratic AI coding tutor that teaches developers on their own codebase instead of writing code for them. It breaks a real task into small steps, asks questions, reviews each line you write, and runs your tests. Every step must pass before the lesson advances.
Engineers ramping on an unfamiliar codebase, teams who need onboarding that leaves something behind, and anyone who can ship AI-written code but would rather also understand it.
In your browser with nothing to install, or as a free open-source agent that serves its UI on 127.0.0.1 and keeps your code on your machine.
The core tutor is free and open source. The managed tutor is free for 10 lessons a month, and Pro adds your own private repos from $24.
Longer reads: how a Socratic coding tutor works, and learning any codebase in 30 minutes.
As AI writes more of the code, the understanding behind it erodes. Juniors ship features they can't debug. Onboarding still takes months. "It works" stops meaning "we know why."
The discovery phase of learning, where understanding actually forms, gets skipped when the answer is one tab away.
Source: Digital Education Council, 2026
Generic courses teach someone else's code. Your patterns, your standards, your gotchas go untaught.
Source: engineer onboarding ramp-up analysis
Seniors burn their week answering the same questions. Skill doesn't compound; it leaks.
Source: SHRM turnover-cost research
No videos, no toy exercises. A Socratic tutor asks, nudges, reviews what you wrote, and runs the tests, but it never hands you the answer.
Paste any public repo URL on the free tier and the lesson is built from the code that's actually in it. Say what you want ("how the API works", "the auth flow") and it aims there. On Pro, repo mode runs against your own checkout and edits land in your real branch, on 127.0.0.1, so your code stays local. Secrets and gitignored files are never read, in either mode.
The tutor breaks the work into tiny steps in a real editor with an instant Run button. You type the line; it reviews what you wrote and explains what changed.
Stuck? It shrinks the step or reveals the next hint, never the solution. Failing code is the best teaching moment, so it leans in instead of bailing out.
The concepts you got stuck on are scheduled to come back at widening intervals. One click turns a due concept into a fresh drill built from what you actually got wrong, not a replay of the lesson. Syncs across the browser, the agent, and the open skill.
CodeTrain is laid out like a transit map. A course is a line, each class is a stop along it, and every class is a set of hands-on lessons where you write each small step yourself. Start free on any live class; the rest of each line rolls out stop by stop. These curated tracks are just the on-ramp: ask for any topic and CodeTrain builds the lesson on the spot, paste a 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.
Built from your repo and standards. Not generic katas (Codecademy, Scrimba), and not a course generated from docs that went stale three sprints ago.
Hands-on by design. Reading an explanation isn't learning; producing the code is. That's the difference from AI explainers.
Every step has to actually run and pass before the lesson moves on. What you get back is evidence someone can do the work in your repo, not a percentage on a dashboard.
With the free skill and the codetrain agent your code stays on your machine. Only small prompt snippets cross the wire (or, with your own key, nothing but a license check). The managed in-browser tutor sends what you submit; see our privacy policy.
A free tutor helps one dev. A team needs to standardize and measure understanding. This is not an LMS. Nobody watches a video and clicks "complete." They write code in your repo, it has to pass, and you get the record.
Configure your repo, standards, and a safe first task; CodeTrain runs each new hire through an interactive journey to an early win. They ramp in weeks, not months, without tying up your seniors.
A team dashboard shows each member's finished lessons, concepts, and usage at a glance. Per-seat budgets keep spend predictable; bring your own model key for your data on your account. SSO/SCIM, audit logs & self-host are available for Enterprise. Talk to us.
Start free. Upgrade when you want your real repos, your own model key, or your whole team. No card to start.
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. Stuck learners get a smaller step or the next hint instead. The full rule set is published here.
Opposite jobs. Copilot and Cursor exist to produce code faster, and they are good at it. CodeTrain exists so the person who shipped that code can still explain and change it in six weeks. One is a typing accelerator, the other is a tutor that refuses to type. Most teams should run both. Where each one fits, including when not to use us.
Yes, two ways. The free open-source 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. In every mode, secrets and gitignored files are refused before they are read.
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, and steps run in a real sandbox. Browse every course.
No. The agent runs on your machine and serves the UI on localhost. On the managed plan, only short prompt snippets go to the model. On Bring-Your-Own-Key (Team/Enterprise), model calls go straight to Anthropic with your key, and nothing but a license check touches our servers.
The opposite. Explainers do the work for you. CodeTrain makes you write every line, reviews it Socratically, runs your tests, and schedules the concepts you didn't get to come back as a fresh drill days later. You finish able to do it without help.
For most subjects you should. They are free, they teach well, and they put diagrams and video inside the explanation, which we do not do at all. The gap is code specifically. There is nowhere to type, nothing you write gets executed, and nothing can tell you your version is subtly wrong because nothing ran it. Here you type every line, it runs against the step's criteria before you move on, and a lead gets a record of what you did unaided. The full comparison, including when not to use us.
Those make your team faster at producing code. This makes sure they still understand it, and gives you a way to prove ramp and retention. Different job. They're complements, not competitors. Full comparison, including when not to use us.
Those tools turn documents into courses. In software the documents are the least reliable thing you own; the repo is the source of truth, and it moved this morning. A generated course also can't tell you whether anyone can actually do the work, because nothing executes. It grades a written answer against a rubric and reports a completion percentage. CodeTrain builds the lesson from the code itself, makes the engineer write each step, and runs it. If it doesn't pass, the lesson doesn't advance. Different input, different proof. Full comparison, including when not to use us.
You connect your own Anthropic (or Bedrock) API key. Your code and prompts go directly to the model on your account. That is best for security and cost control, and we just provide the software, accounts, and dashboards.
Yes. The core tutor is a free, open skill you can run today. Paid plans add zero-setup managed access, your real repos, cross-device sync, and the team layer.
Spin up a lesson on your own repo in two minutes. Free to start.