Technical SEO Checklist: Fix Foundation Issues First

In Google Search Console → Coverage report. Error pages: 5xx (server errors — fix immediately), 4xx (not found — redirect or restore). Excluded pages: check "Crawled - currently not indexed" and "Discovered - currently not indexed" — these may need content improvement or indexing priority adjustment. Use the URL Inspection tool to diagnose any specific page's indexing status.

A canonical tag (<link rel="canonical" href="URL">) tells Google which version of a page is the preferred one when multiple URLs serve similar or duplicate content. Use canonical tags when: (1) Your site is accessible via both HTTP and HTTPS (canonicalize to HTTPS), (2) www and non-www versions both resolve (canonicalize to one), (3) URL parameters create duplicate pages (/products?sort=price and /products should both canonical to /products), (4) Paginated content — /category/page/2 may canonical to /category/ if pagination is handled via JavaScript, (5) Syndicated content published on external sites — the external site should canonical back to your original. Every page should have a self-referencing canonical tag (pointing to itself) as a best practice to prevent crawler confusion. Incorrect canonicals are one of the most common technical SEO issues.

Diagnosis process for indexed-but-not-ranking pages: (1) Check Google Search Console → Performance → filter by the specific URL — is it appearing for any queries at all? If zero impressions, Google may be ignoring it despite indexing, (2) Search intent check: Google your target keyword and review page 1. Does your page format match the content type Google is ranking? (article vs product page vs tool), (3) Content quality assessment: is your page as comprehensive and authoritative as the pages ranking above you? Use Ahrefs Content Gap to identify topics they cover that you do not, (4) Backlink comparison: check referring domains of top-ranking pages vs yours — a significant backlink gap is the most common reason for ranking plateaus, (5) E-E-A-T evaluation: does your page demonstrate Experience, Expertise, Authoritativeness, and Trustworthiness? Add author credentials, cite sources, add real examples and data. Most non-ranking indexed pages have one or more of: wrong intent, thin content, or insufficient authority.

Structured data is machine-readable markup (JSON-LD format recommended by Google) that helps search engines understand your page content and display rich results. Priority order for implementation: (1) Organization schema on homepage — enables Knowledge Panel, (2) FAQPage schema on any page with Q&A — displays expandable questions in SERPs, significantly improving CTR, (3) Product + AggregateRating schema for e-commerce — star ratings in SERPs improve CTR 15–35%, (4) Article schema on blog posts — enables article rich results, (5) LocalBusiness schema for local businesses — supports Local Pack rich results, (6) BreadcrumbList sitewide — breadcrumbs in SERP URLs. Validate all implementations with Google Rich Results Test before deploying. Check Search Console → Enhancements reports 2 weeks after deployment to ensure no errors.

JavaScript-heavy sites (React, Angular, Vue, Next.js) present specific SEO challenges because Google must render JavaScript to see content, which adds a processing step that can delay indexing. Key JavaScript SEO fixes: (1) Use Server-Side Rendering (SSR) or Static Site Generation (SSG) for critical content and navigation — content in the initial HTML response is crawled immediately, (2) Test what Google actually sees: use Search Console URL Inspection → "View Tested Page" → "More Info" → check the rendered HTML, (3) Ensure internal links are real <a href> elements, not JavaScript event listeners — Google cannot reliably follow JavaScript-triggered navigation, (4) Avoid content hidden in tabs, accordions, or lazy-loaded sections that only load on user interaction — Google may not execute these interactions, (5) Check Screaming Frog in JavaScript rendering mode to see what content is actually crawled vs what requires JavaScript execution.