I run a small niche site called PetHuts that provides free tools for people building bioactive terrariums and vivariums. It has 7 interactive calculators, all built as WordPress shortcodes — no page builders, no calculator plugins, no React, no build step. Here's how and why I did it this way. Why Shortcodes Instead of a Plugin? Most WordPress calculator plugins are bloated. They load their own CSS frameworks, jQuery dependencies, and admin interfaces even on pages that don't use them. For a site where speed matters for SEO (mine went from 8.9s to 3.7s LCP after optimization), every unnecessary script hurts. A PHP shortcode is just a function that returns HTML. WordPress calls it when it encounters [your_shortcode] in a page. The CSS and JS are inline, so nothing loads on pages that don't use the calculator. Zero overhead.…