CodeTrain

What CodeTrain Does

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, so what you finish with is a record of the steps you wrote unaided rather than a completion percentage.

The core idea is simple. An AI coding assistant answers the question you asked. A Socratic coding tutor answers with the question you should have asked next. Both are useful, but only one of them leaves you able to do it again tomorrow without the tool open.

Key Features

• Learn on real code, not toy exercises. Point CodeTrain at any public repository URL and it authors the lesson from the code that is actually in it. You practice on the thing you actually have to work in.

• Small steps in a real editor. Each step is a handful of lines with a Run button. Nothing advances until your code passes its criteria.

• You write every line. The tutor asks questions and reviews your work. It never hands over the fix, so the solution stays yours.

• Two lesson modes. Explore is read only, so you learn the code and nothing on disk moves. Guided means you are making a real change, and the work comes back as a single reviewable patch.

• Runs in your browser and locally. Python and JavaScript lessons run in the tab with nothing to install. Pro can run the same thing against your own checkout on 127.0.0.1, where the code never leaves your machine.

• Built in secret protection. A fixed denylist keeps .env files, private keys, certificates, service account JSON, keystores, and VPN configs from ever reaching the model or your browser. Gitignored files are skipped too.

Who It Is For

CodeTrain is built for developers who want to actually understand the code they work with, not just ship features they cannot debug. It suits engineers onboarding onto a new codebase, juniors who want to build real skills instead of copying output, and teams that need evidence of what someone can write without help. It is also useful for anyone preparing to work in an unfamiliar repository and wanting a fast, hands on path through it.

Why It Stands Out

As AI writes more of the code, the understanding behind it erodes. Juniors ship features they cannot debug, onboarding still takes months, and the discovery phase of learning gets skipped when the answer is one tab away. General AI study modes are excellent for most subjects, but they are conversations. There is nowhere to type, nothing you write is executed, and nothing tells you when your version is subtly wrong. CodeTrain is different because the step does not advance until your code actually runs and passes. The struggle is not a side effect of the method, it is the method.

There is also a second, quieter difference. In a general assistant, the refusal to give the answer is a setting, and settings get switched off at exactly the moment learning would have happened. In CodeTrain there is no mode that writes the code for you. The step still needs code you wrote yourself.

Getting Started

You can try a mock lesson right in your browser with no account and no install. Two steps, about a minute. Then with a free account (no card) paste any public repository URL and let the lesson build itself from the code that is really in it. Whether you want to understand a codebase in thirty minutes or build a habit of writing code you can still read in six weeks, CodeTrain delivers a hands on path through it.