Build a little tool for yourself

So far everything you’ve built has been a web page — something that lives in a browser. But the exact same skills can build a small tool that just does a job for you on your own computer. A little helper. The kind of thing you’d otherwise do by hand, over and over.

This module shows you what’s realistic, what to skip, and walks through building one for real.

what “a tool” can mean

There are two beginner-friendly shapes a tool can take. You don’t have to memorise the difference — your assistant will pick the right one. It just helps to know they exist:

• A little web tool — a single page with some buttons that you open in your browser, exactly like the project you already made. Good when the tool needs to look like something: a tip splitter, a unit converter, a random name picker for game night.
• A script you run in the terminal — a small file you run with one command to do a job, usually with files. Good for chores: tidying a messy folder, renaming a batch of photos, pulling a list out of something. A script A small file of instructions your computer runs top to bottom to do one job. You run it with a single command. is just a tool without buttons.

The good news: you already know how to make the first kind. The second kind is new, and it’s what the rest of this module focuses on, because it’s where a tiny bit of effort saves you the most repetitive time.

the rabbit hole to skip (on purpose)

You might wonder: can I make a real Windows program — the kind with an installer, that shows up in my Start menu like a normal app?

Technically yes. But it’s a genuinely deep, fiddly world, and none of it is worth your time right now. Packaging a program into an installer means wrestling with code-signing certificates A paid digital stamp that proves an app came from you. Without it, Windows shows scary 'unknown publisher' warnings. Costs money and renews yearly. , the “Windows protected your PC” warning that pops up for unsigned apps, and a pile of setup that teaches you nothing about building.

build one for real — a folder tidier

Let’s make an actual tool: one that looks at a messy folder and sorts the files into subfolders by type (images together, PDFs together, and so on). You almost certainly have a Downloads folder that could use it.

This uses Node The engine you installed back in Module 2. As well as running websites, it can run small scripts on your computer. — which you already installed in Module 2, so there’s nothing new to set up.

First, make a home for your tools. Open VS Code’s terminal (Module 4) and make a folder, the same way you made your project folder:

PS> cd ~\Projects
PS> mkdir tools
PS> cd tools
PS> code .

Now start Claude Code in that folder’s terminal and describe what you want. Notice this is the same move as always — plain English, and one clear request:

I want a little tool I can run on my Windows computer.
It should look at a folder I choose and move the files in it
into subfolders by type — images into an "Images" folder,
PDFs into a "Documents" folder, and so on.
Use whatever is simplest to run on Windows, explain what
you're doing as you go, and tell me exactly how to run it.
Before it moves anything, have it list what it's about to
do and wait for me to say yes.

That last line — list what it’s about to do and wait for me to say yes — is your safety net. It turns a tool that quietly moves your files into one that shows you the plan first.

running your tool

Your assistant will create a file (something like tidy.js) and tell you the exact command to run it. It’ll look something like this — but use the command Claude gives you, since the filename and the way you point it at a folder may differ:

PS> node tidy.js

Press Enter, read what it says it’s about to do, and tell it to go ahead. That’s your tool, working.

The best part: it doesn’t disappear. Any time you want to run it again, open that folder, open the terminal, and run the same command. You built it once; you can use it forever.

a few ideas worth building

Once the folder tidier clicks, the pattern opens up. Things people commonly make in an afternoon:

• Rename a batch of files to a tidy, consistent pattern (great for photos).
• Make a list of everything in a folder and save it to a text file.
• A little web page tool — a tip splitter or countdown timer you keep bookmarked.
• Pull the useful bits out of a messy file into a clean one.

The recipe is always the same: describe the chore in plain English, let Claude build it, test it somewhere safe, then keep it around.

the same good habits apply

Nothing new to remember — your existing habits cover tools too:

• It still costs the same way. Building a tool uses your assistant just like building a page does, so the Module 8 habits (stay on Sonnet, one task per conversation) keep it cheap.
• You can save tools too. A tool you love is worth keeping. The Module 5 commit-and-push routine works on a tools folder exactly the same way.
• When it breaks, you know what to do. Module 9 is your friend here as much as anywhere.
• Keep secrets out of tools too. If a tool ever needs a password or key, don’t type it into the file — ask your assistant for the safe way (the same .env habit from Module 5).