I built TrustGate from scratch — a business review and trust platform for the Indian market. Think verified business profiles, customer reviews, owner responses, and an embeddable trust badge that pulls live data. The entire backend runs on a custom WordPress plugin using the REST API exclusively. No admin-ajax.php . Not a single call to it. This post is about what I learned building it, what broke, what I got wrong the first time, and the decisions that actually held up. Why REST API and not admin-ajax When I started, the easy path was admin-ajax.php . Every tutorial uses it. It works. But it has real problems for a platform of this type. Every request, regardless of whether a user is logged in or not, boots the entire WordPress admin. That is expensive. For a review platform where anonymous users are searching and browsing businesses constantly, that overhead adds up fast. The REST API routes only load what they need. Public endpoints run lean.…