A technical SEO checklist is your operational guide for the backend infrastructure that determines whether Google can find, understand, and rank your pages. Unlike content or link building, technical SEO deals with what happens under the hood: server configurations, code efficiency, and crawl accessibility. The core components fall into several buckets. Crawlability covers your robots.txt file, XML sitemap accuracy, internal linking structure, and whether you're blocking important pages accidentally. Indexability means canonical tags are set correctly, no orphaned pages exist, and you're not wasting crawl budget on duplicate or thin content. Site speed includes server response time (aim for under 200ms), image compression, browser caching, and minified CSS/JavaScript. Mobile-friendliness has been a ranking factor since 2015, so responsive design and touch-element spacing matter. Core Web Vitals now measure LCP under 2.5 seconds, FID under 100ms, and CLS under 0.1. Structured data markup helps Google understand your content type, whether that's local business schema for Ottawa companies or product schema for e-commerce. SSL certificates (HTTPS) have been table stakes since 2014. URL structure should be clean, descriptive, and free of unnecessary parameters. You need proper 301 redirects for moved content, 404 handling for dead pages, and no redirect chains longer than two hops. At Ottawa SEO Inc., we run this checklist quarterly across our 500+ domain portfolio because technical debt accumulates fast. A site that scored 95 on Lighthouse six months ago might drop to 72 after a WordPress update or new plugin. We prioritize fixes by impact: a broken sitemap affects every page, while one slow-loading image affects one URL. The checklist isn't one-and-done; it's a recurring audit that catches regressions before they cost you rankings. Most agencies sell technical audits as standalone deliverables, but the real value is in monitoring trends over time and catching issues within days, not months.