Free during testing Windows now, Mac in testing

Read the code your AI writes. Then write your own.

KohAI is a desktop app that works alongside the AI coding tool you already use. Your AI builds the software. KohAI explains each change line by line, checks that you understood it, and teaches you to write code yourself.

Download KohAI Find your level

Works with Claude Code, Codex or Gemini CLI. Your code and your AI login never go to KohAI.

Hi, my name is KohAI.

How it works

Your AI writes the code. KohAI makes sure you understand it.

Scroll to follow one small request from prompt to explanation. The app does this after every change your AI makes.

You Split a bill between friends, with a tip.

def split_bill(total, friends, tip=0):    with_tip = total * (1 + tip / 100)    return round(with_tip / friends, 2) print(split_bill(120, 4, tip=20))

  1. Line 1

    A function gets a name

    What it is. A function is a named set of instructions you can use again. This one takes three inputs: the bill, the number of friends and the tip.

    Why it is there. Writing tip=0 means the tip is zero when you leave it out. Nothing breaks if you forget it.

  2. Line 2

    The tip goes on top

    What it is. A sum that is stored under a name. With a tip of 20, the part in brackets becomes 1.2, so a bill of 120 becomes 144.

    Why it is there. Giving the result a clear name makes the next line easy to read.

  3. Line 3

    Divide it and return the result

    What it is. The total is divided by the friends and rounded to two decimals. The word return hands the answer back to whoever asked.

    Why it is there. Money has cents. Without the rounding you could get 33.333333 on a receipt.

  4. Line 5

    Run it and check the result

    What it is. This line uses the function with a bill of 120, four friends and a 20 percent tip, and prints what comes back: 36.0 each.

    Why it is there. A quick test. If the number looks wrong, you know before anyone pays.

  5. Your turn

    Then it checks what you learned

    You predict what a line does before you read the explanation, and short questions follow. Correct answers raise your level, and the explanations go deeper as you improve.

    Try a lesson

Try it here

Try a one minute lesson.

Three questions in the same formats the app uses. Nothing is stored.

Three modes

Build with your AI. Learn the fundamentals. Practice on your own.

Build

Every change your AI makes, explained.

Work with your own AI as usual. Each file it changes appears as a card in plain language, and a walkthrough takes you through the lines that matter. You predict first, then read the explanation.

Learn

Structured lessons, from the first line to real projects.

Each lesson introduces one concept with a worked example, then tests it: choose the answer, fill the gap, order the lines, find the broken line, write the code. Lessons run offline and need no AI.

Practice

Write code yourself and get it reviewed.

Choose a task and write the solution. Ask for a hint when you are stuck. When you submit, your own AI reviews it: what works, what to fix, and on which line.

Built for consistency

Progress you can see, so you keep coming back.

Learning to code takes months, not days. KohAI rewards steady practice and never punishes a mistake.

  • A level from 1 to 1000

    Every lesson, check and task earns experience points. Your level never goes down.

  • A streak

    The number of days in a row with at least one lesson, check or task. A few minutes is enough to keep it.

  • Chests and gems

    Chests are earned through progress, never sold. They hold gems to spend in the shop.

  • Pets and outfits

    Customize Brackets, choose a color theme, and add a pet to your workspace.

Try something on

Pick a pet

Privacy

Your code and your AI login never go to KohAI.

That is how it is built, not a setting you have to find.

Your login stays yours

KohAI never holds your AI login or a key. It starts the tool you installed and signed in to yourself, unchanged.

Your code stays on your computer

KohAI never uploads your code, file names or chats. Your code goes only to your own AI tool, exactly as it does without KohAI.

No AI bill from us

Every explanation, hint and grade is written by your own AI tool, on the plan you already have.

You need one of these, installed and signed in:

  • Claude Code
  • Codex
  • Gemini CLI

KohAI is independent. It is not made by, affiliated with or endorsed by Anthropic, OpenAI or Google.

The level test

What is your coding level?

Ten questions on real code, the kind your AI writes for you. The difficulty adapts to your answers. About three minutes, no sign up, and your answers stay in your browser.

Start the test Available in six languages.

Questions

Common questions.

Is it free?

Yes, during testing. Paid plans come later, and we will tell you well before anything changes. KohAI never charges for AI: explanations and grades come from your own AI tool, on the plan you already have.

Which AI tool do I need?

One of Claude Code, Codex or Gemini CLI, installed and signed in on your computer. Use the one you already have. The Learn lessons also work without any of them, and offline.

Does KohAI see my code?

KohAI reads your project on your own computer, to show what changed and to build the walkthrough. It never uploads it. The only thing the app sends to us is the sign in for your free KohAI account.

Windows or Mac?

Windows works today. The Mac version is in testing. Phones and tablets are not supported: KohAI sits next to your coding tool on a computer.

Do I need to know how to code?

No. Lessons start from the first line of code, and every technical term is explained when it first appears. Explanations become more detailed as your level rises.

Which languages does it speak?

The app and its lessons come in English, Dutch, German, French, Japanese and Simplified Chinese. Code stays code in every language.

Join the wait list.

Leave your email and we will let you know when the next version is ready and when the Mac version opens.

On a computer right now? Go to the download page