Bálint’s Side Project: A web-based calculator app that’s easy to share

“The solution I created is web-based, so there’s a URL for every calculation. You can always share it.”
– Bálint Kléri, CTO

Bálint and I sat down (in different countries) to talk about the shareable web-based calculator app he built over the winter break. Here’s what he had to say.  


Can you tell me a little bit about the project and what it was that you built? 

Last year I switched from using macOS to Linux as my main operating system. And there was this calculator app on macOS called Numi that I was totally into. (Now I’m back to macOS again, but that’s another story.)


I loved doing quick calculations with it. I used it as my calculator app and there was no alternative for Linux. 


I started wondering if I could recreate my favorite features from Numi, for the web and possibly even more. The web is what I know. And I needed a solution quickly.


So, that was the motivation for the app and I wanted to have some fun during the Christmas break. So, that’s what I did. 


On one monitor, I was watching the Fast and the Furious movies (don’t judge me!). And then on my other monitor, I was coding the calculator. By the third movie, I had it working. 


I love how you have fun. So, what were you using Numi for when you were working on Mac OS? Personal things or for the company?  

Anything. Whenever I needed to calculate something, I would use it. Even for the company stuff, very quick notes, some quick estimations on projects. Things like that.


What does this calculator app do that you haven’t found anywhere else? 

Well, Numi is a desktop app, so there was no way of sharing calculations, unless it was a text file. If I ended up doing a calculation that could be useful for others — like an estimation for a project — there was not an easy way to share it. The solution I created is web-based, so there’s a URL for every calculation. You can always share it. 


Can you expand on that?

My calculator app is like a sheet of paper where each line gets a result on the side. It is designed to do calculations where you use your own variables. E.g. you can define a rate for a project’s cost calculation instead of typing the same number all over again. Then updating the rate would update all calculations that use it. Almost like a simplified spreadsheet. You can even write your own functions.

Here’s an example.

When you open the app what you see is a blank page. Anything you type will get immediately encoded and added to the URL. This way your calculation will always have a URL that you can share with others. When they open it, they will see exactly what you entered previously. I like the simplicity of storing everything in the URL. It allowed me to keep this little project lean and focused on one thing — calculations.


How are you and the rest of the team currently using this?

When we talk about cost for a project or estimations for a project, we usually share a link. From this app, we put in some quick numbers, add in notes because you can add notes in the calculations and we send that to each other.


How did you build it?

The project is heavily based on an open source library called Math.js. When it comes to executing those calculations, the heavy lifting is done by this library. I’m just piecing some things together.


Is it available for anyone to use?

Yes. The URL is public. There is no authentication and we don’t actually plan to introduce any kind of authentication or anything or any data tracking. It’s really just a pet project.

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