KuxCal

The case study

Problem

Financial calculators in Mexico are often inaccurate, slow and buried under ads.

Solution

A suite of calculators —investments, CETES, loans and savings— built with Astro to ship static HTML, with no friction and no distractions.

Outcome

A free, fast and precise tool focused on one thing: helping people decide with clarity.

Process

Development process

The reasoning behind the technical decisions: why each technology was chosen, what challenges came up and how they were solved.

1. 01

   Astro and static HTML

   I chose Astro because it ships no JavaScript by default: each calculator is served as static HTML that loads instantly, and only the calculation logic reaches the client as a small island. For a tool people open, use and close, first-load speed is the most important feature.

2. 02

   TypeScript for correctness

   Money is unforgiving with rounding and unit errors. TypeScript let me model rates, terms and amounts with explicit types, so many mistakes are caught while writing the code instead of when someone trusts a wrong result.

3. 03

   Precision over noise

   The biggest challenge was not technical but trust: I validated every formula (compound interest, CETES, amortization) against official sources and deliberately left out ads and distractions. The interface exists for one thing: helping people decide with clarity.