Part 1: Build Your Own Mortgage Calculator - Get a Live Website Before You Write a Single Line of Code

A project that used to cost $10,000+ can now be built BY YOU for $20. This is what we're here for, to do the impossible and put the power to create in everyone's hands. So let's go!

I'm building A calculator that gets Canadian math right, that I can send a client as a link, and that holds no personal information whatsoever. I'm doing it with AI, on video, in five-minute pieces, so you can watch someone who is not a developer do it and decide for yourself whether you could.

This is Part 1. Fair warning: at the end of it, my website shows an error page.

Watch Part 1 on YouTube: Building a Mortgage Calculator With AI: The Setup. Five minutes. The rest of this post is the written version, with the bits that are easier to copy than to pause a video for.

The part nobody films

Every "build an app with AI" video I have ever watched skips straight to the magic. Someone types a sentence, a beautiful interface appears, everyone claps. What they leave out is the twenty minutes beforehand where nothing works, because the interesting part sits on top of a boring part that never makes the edit. So I filmed the boring part.

By the end of this episode there is a real website at a real address that you could open on your phone from another country. There is nothing in it. But the pipe from my laptop to the internet is built, and I never have to build it again, not for this project, and not for the next one.

Run the plumbing before you decide where the sink goes.

One page first. Still.

I wrote a whole post about this and I am not going to repeat it here, but I did the thing I told you to do. Before I touched a single tool I wrote one page describing what I was building. Six questions. What problem this solves, what success looks like, what goes in, what comes out, who touches it, and the one everybody skips — what am I explicitly not building.

That last question did more work than the other five combined. My "not building" list includes any field that holds a name, an address, a SIN, an income figure, or a credit score. Not "we will be careful with that data." There is nowhere to put it. You feed it five numbers and it gives you a payment.

If you work in this business you already know why that matters. The fastest way to turn a useful side project into a compliance conversation is to let it start collecting things. Deciding that on paper, before a single file exists, costs nothing. Deciding it after you have built a form costs a rebuild.

The three things you set up

Here is the entire stack for Part 1. It is shorter than you would expect, and all of it is free.

Git is a program that lives on your computer and tracks changes to files. You install it once and then never open it directly — other tools use it on your behalf. Get it from git-scm.com. On Windows the installer asks about ten questions you have no way of answering: editors, line endings, terminal emulators. Click Next on all of it. The defaults are correct and I have never changed one of those screens in my life. On a Mac, open Terminal, type git --version, and your Mac will offer to install it for you.

GitHub is where the project lives online. If Git is the thing tracking your changes, GitHub is the shared copy that everything else reads from — the recipe book on the shelf that anyone with permission can look at. Free account, create a new repository, keep it private. One thing on that screen matters and I will come back to it: tick the box that says "Add a README file."

Vercel is what puts it on the internet. Sign in with your GitHub account, click Import next to your repository, click Deploy. That is the entire configuration.

What Vercel actually does is worth understanding, because it is the part that feels like magic later. It is not a place you upload a copy of your site to. It watches your GitHub repository. Any time anything changes there, Vercel notices within seconds, rebuilds, and republishes. You wire that up once and then you stop thinking about it forever.

Three tools. Maybe six minutes of clicking. Nothing to configure, nothing to pay for, nothing to maintain.

The three things that broke

I wanted to leave all of these in the video, because watching somebody recover from a small mess is more useful than watching a clean take, but it took the video to 10 minutes, so I didn't. Know this: I screwed up and re-filmed this 5 times. This 5 minute video took me an hour... It's ok to screw up. 

The empty repository would not deploy. I created the repository on GitHub without ticking the README box, so it was genuinely, completely empty. Not one file in it. Vercel refused — there was nothing to build. The fix took thirty seconds: go into the repository, create a file called README.md, put one line in it, commit. Or tick the box in the first place. That checkbox exists for exactly this reason.

Vercel said the project name was already taken. I had clicked Deploy once before, hit an error, and assumed nothing had happened. Something had happened. The project got created and then the deploy failed, so my second attempt collided with my first.

Then Vercel quietly renamed my project. On the retry it pre-filled the name as mortgage-calc-jxdb. Not an error — it noticed the collision and added a random suffix to route around it. Helpful, right up until you realise that suffix becomes your live web address and you are about to read it out loud on camera. I went back, deleted the abandoned project, and started again with a clean name.

There is a pattern in all three. Nothing was actually broken. Every one of those messages was a tool telling me something true about the state of the world, in language that assumed I already knew what it meant. That is most of what "technical difficulty" turns out to be. The gap is not intelligence. It is vocabulary, and vocabulary is the cheapest thing on this list to acquire.

And then, the 404

Deploy went green. I opened the address on my phone.

404: NOT_FOUND

Which is correct. A README is not a webpage. There is no home page in that repository yet, so there is nothing to show — the site is working perfectly and displaying the honest answer, which is "nothing here."

I want to sit on that for a second, because it is the actual result of Part 1 and it is easy to undersell.

There is now a live address on the public internet. It works on any device, anywhere. It is wired to a repository that Vercel is watching every second of every day. The moment a real page appears in that repository it goes live on its own. No uploading. No server. No FTP. No IT ticket and no phone call to anybody.

I did not build a calculator. I built the thing that will publish the calculator the instant it exists. Five minutes of work I will never do again.

Part 2

Next episode I open Claude, point it at that folder, and describe what I want in plain English. The 404 becomes a real page, and I do not write a line of code to make it happen. Then we go back to Vercel — not to do anything, just to watch. A build starts by itself about thirty seconds after Claude finishes. That is the loop, and once you have seen it once you cannot unsee it.

If you want to follow along, do the three things above before Part 2 goes up. Fifteen minutes, no cost, and you will be standing exactly where I am: looking at your own 404 and understanding, for the first time, why that is a good sign.

Part 2 is Claude writing the first real page. Part 3 is the calculator itself, and getting Canadian mortgage math right. Part 4 is saving and sharing a scenario. Part 5 is polish, and what to build next.