ZFlex Selantes.

ZFlex Selantes Técnicos manufactures industrial sealants in Limeira-SP, and since October 2023 I am the sole developer behind their institutional website. The site increased inbound business contacts and became the company's primary product information channel, used by customers before and after the sale. This is a real client project, in continuous production, with real people depending on it.

The stack is Node.js + Express + EJS with LowDB for lightweight data persistence, totaling 8 production dependencies. That number is intentional: every dependency earns its place. No heavy framework, no build pipeline for the front end, no abstractions that would make a two-year-old project harder to maintain. MVC structure keeps routes, controllers and views cleanly separated without ceremony.

The front end ships as a PWA with a manually written service worker. Pages load via network-first (always fresh when online, falls back to cache when offline), while static assets (CSS, fonts, images) use cache-first for instant repeat visits. The design system is entirely in CSS custom properties: responsive typography with clamp() across breakpoints, an elevation system, category tag styles, all written without Tailwind or any preprocessor. The goal was a design that looks professional without any framework opinion baked in.

Security on the contact form uses reCAPTCHA Enterprise (not v2/v3 checkbox) combined with server-side field validation via the validator library and Nodemailer for email delivery. On the infrastructure side, the app runs as a Docker container on GCP Cloud Run (serverless, scales to zero, no fixed VM cost) with CI/CD via Cloud Build: push to main, container builds and deploys automatically.