Search engine optimization has evolved dramatically over the past few years. What once involved manually reviewing web pages, checking metadata, and analyzing content now requires a more scalable approach. As websites grow into hundreds or thousands of pages, traditional SEO audits become time-consuming, repetitive, and difficult to maintain. I encountered this challenge while working on large-scale content projects. I needed a way to automatically audit websites, identify SEO issues, generate recommendations, and produce structured reports without manually reviewing every page. That need led me to architect an automated Programmatic SEO Auditor powered by Node.js and Large Language Model (LLM) function calling. In this article, I will walk through my thought process, architecture decisions, implementation strategy, and the lessons I learned while building the system.…