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Build Your Own Tool With Claude, and Never Lose It

Describe the tool in plain English, fix it by using it, then put it somewhere 11:05pm can't destroy it.

4 min read · Last verified 2026-10-27

Every annoying little calculation you do on a notepad. Every quoting rule of thumb that lives in your head. Every spreadsheet you rebuild from scratch each time.

You can turn those into a real tool tonight. Buttons, fields, the math done for you. And you don't write a line of code.

This is the whole process, start to finish, plus the part everybody skips: making sure you never lose it.

Step 1: Describe the outcome, not the method

You don't need words like HTML or CSS. Describe it the way you'd describe it to a person you hired:

Build me a simple calculator I can use when I'm quoting a client.
I type in: hours, my hourly rate, materials cost.
It shows me: the total, and my margin as a percentage.
Make it one page, big clear numbers, nothing fancy.

3 things in every good ask:

  • What goes in. The fields you'll type into.
  • What it does. The math, in plain words.
  • What comes out. What you need to see at the end.

That's it. Send it.

Step 2: Use it before you judge it

Claude builds it right there. Type real numbers in. Change one. Watch the total move.

Then go looking for what's wrong with it. That's not a failure, that's the job.

Step 3: The fix loop (this is the actual skill)

You find a problem by using it, and you say it in plain words:

The discount box shouldn't let me go above 25 percent.
Add a field for a trip charge.
Make the total bigger, I can't read it from across the room.

Every one of those is a real request. Every one of them works. You never touch the code.

The building isn't the skill. The fixing is. Most people stop after the first version because it's a bit rough. It's supposed to be rough. Permission to start ugly.

Rest of it's yours

Drop your email and the whole thing opens up right here. No waiting on a confirmation, no download, nothing to install.

You'll also get the new ones as I make them. Leave whenever, no hard feelings.

Step 4: Make it a file on your computer

In a chat on the website, your tool lives in that chat. Fine for trying it out.

If you're using the Claude desktop app with a folder open, ask it to save the tool as a file:

Save this as quote.html in this folder, then open it in my browser.

Now it's a real file. It opens in any browser. It doesn't disappear when you close a tab, and you can double click it any time you need it.

Bonus move: if your rates already live in a file in that folder, tell Claude to use them. "Use the rates in my pricing spreadsheet." You don't retype a single number.

Step 5: The undo button (GitHub, explained like you're not a developer)

Here's the problem nobody warns you about. You build something at 11pm. At 11:05 you ask for one more change. It breaks everything, and you can't remember what it looked like when it worked.

GitHub fixes that. Forget everything you've heard about it being for programmers. For you, a repo is a folder with a memory. Every change is saved, with when it happened, and you can go back to any of them.

Setting one up:

  1. Make a free account at github.com.
  2. Click New repository. Give it a name. quote-tool is fine. Naming it is the hardest part, honestly.
  3. Set it to Private. Public means the whole internet can read it. Private means you and whoever you invite. You can always open it up later. You can't un-publish something somebody already copied.
  4. Tick Add a README. It's a note on the front of the folder explaining what this is, for you in 6 months when you've forgotten.
  5. Pick a .gitignore from the dropdown. It's the list of files that must never go up. More on why in the next guide.
  6. Create it.

Then the easiest way to get your tool in there: in the desktop app, ask Claude to do it.

Put this folder in my private GitHub repo called quote-tool, and save a version every time we make a change that works.

Step 6: The commits page is the whole point

Open your repo and click Commits. Every saved version, when it happened, and what changed.

That list is why you're doing this. Not collaboration, not open source. The fact that nothing you build is ever unrecoverable.

When something breaks, you say:

Go back to the version from before the discount change.

And you're back.

What to build first

Pick the thing you do most often by hand:

  1. A quote or price calculator. The one above. Everybody has one living in their head.
  2. A checklist that ticks off. The steps you always forget.
  3. A tracker. Who owes you what, what's due when.
  4. A converter. Whatever you keep looking up or working out on your phone.

Build 1 tonight. Break it. Fix it by talking to it. Back it up.

That's how you go from "AI is a chatbot" to "I make my own tools."

Take it with you

The whole thing as a PDF. Print it, save it, come back to it when you get stuck.

Download Build It and Back It Up (PDF)

There's a lot more where this came from

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