magnus919_agent-skills/seo/references/technical-seo.md

Technical SEO Reference

Technical SEO ensures search engines can find, crawl, interpret, and index your content. If the technical foundation is broken, nothing else matters.

Crawlability & Indexability

Robots.txt

• Purpose: Directs crawlers which URLs to avoid
• Check: Does the site have a robots.txt at /robots.txt?
• Check: Are important pages accidentally disallowed? Disallow: / blocks ALL crawlers
• Check: Is the sitemap referenced? Sitemap: https://example.com/sitemap.xml
• Best practice: Allow CSS/JS files (modern crawlers need them for rendering)
• Hosted CMS sites: Ghost CMS auto-generates robots.txt; verify after any config change

XML Sitemaps

• Purpose: Tells crawlers about all pages and their relative importance
• Check: Does the sitemap exist and is it referenced in robots.txt?
• Check: Are only canonical URLs included? (No pagination params, sort filters, etc.)
• Check: Are noindex pages excluded from the sitemap?
• Check: Lastmod dates are accurate (not all the same date)
• Ghost split sitemaps: Ghost generates sitemap-posts.xml, sitemap-pages.xml, sitemap-tags.xml, sitemap-authors.xml. Verify each is present and valid.
• Hugo: Verify sitemap.xml is generated with correct changefreq and priority settings

Canonical URLs

• Purpose: Tells search engines which URL is the authoritative version of a page
• Check: Every page has a self-referencing canonical or points to the canonical version
• Check: No conflicting canonicals (page A canonicals to B, B canonicals to C)
• Common issues: HTTP/HTTPS duplication (canonical must use HTTPS if site is HTTPS), www/non-www duplication, trailing slash inconsistency
• Ghost: Canonical is auto-generated from the post/page slug. Verify no slug changes break inbound canonical signals.

Meta Robots / Noindex

• Purpose: Prevents indexing of specific pages
• Check: Pages that should be indexed don't have <meta name="robots" content="noindex">
• Check: Thin pages (tag pages, author pages, pagination) have noindex if they shouldn't rank
• Check: Login/admin pages have noindex

Page Speed

Core Web Vitals (Google's ranking signals)

• LCP (Largest Contentful Paint): < 2.5s (good), 2.5-4.0s (needs improvement), > 4.0s (poor)
• FID (First Input Delay) / INP (Interaction to Next Paint): < 100ms (good), 100-300ms (needs improvement), > 300ms (poor)
• CLS (Cumulative Layout Shift): < 0.1 (good), 0.1-0.25 (needs improvement), > 0.25 (poor)

Common Fixes by Platform

Ghost CMS:

• Enable lazy loading for images (Ghost 5+ has built-in)
• Use a CDN for image delivery (Ghost Pro includes; self-hosted needs Cloudflare or similar)
• Limit the number of visible posts on home/tag pages (paginate aggressively)
• Disable unused Ghost integrations and background tasks
• Verify the theme isn't loading unused CSS/JS (many Ghost themes are bloated)

Hugo (example.com):

• Hugo generates static HTML — inherently fast
• Image processing: use Hugo's built-in image processing to serve appropriately sized images (.Resize, .Fill, .Fit)
• Minify HTML output: minify: true in config
• Avoid excessive JavaScript (Hugo sites shouldn't need much JS)
• Verify CSS is not render-blocking (inline critical CSS if needed)

Tools for Measurement

• Google PageSpeed Insights (lab + field data)
• Lighthouse (Chrome DevTools)
• Web Vitals library (RUM data)
• GTmetrix / Pingdom (third-party)

Mobile-Friendliness

• Check: Responsive design — does the site render correctly at all viewport widths?
• Check: Viewport meta tag present: <meta name="viewport" content="width=device-width, initial-scale=1">
• Check: Font sizes are readable on mobile (min 16px body text recommended)
• Check: Tap targets are adequately sized (min 48x48px recommended)
• Check: Content not hidden behind unplayable media or unsupported formats
• Test: Google's Mobile-Friendly Test

HTTPS & Security

• Check: Valid SSL certificate (not expired, not self-signed)
• Check: All resources load over HTTPS (no mixed content warnings)
• Check: HSTS header present for repeat visitors (Strict-Transport-Security)
• Check: Redirects HTTP → HTTPS (301 permanent redirect)
• Check: No security warnings in browser (mixed content, invalid cert)

International SEO (If Applicable)

• hreflang tags: Correctly implemented for multi-language/multi-region sites
• Check: Self-referencing hreflang (each page includes its own language tag as well)
• Check: No conflicting signals (hreflang says X, redirect says Y)

Ghost-Specific Technical SEO

Check	Where to look	Action
Canonical URLs	Post settings → canonical URL	Verify self-referencing or correct canonical
Meta robots	Code injection → per-page	No thin pages indexed
Sitemap	/sitemap.xml	Verify split sitemaps present
Robots.txt	/robots.txt	Verify sitemaps referenced, no accidental disallows
Structured data	Source HTML → JSON-LD	Verify Ghost's built-in JSON-LD is correct + any custom
AMP	Ghost settings	Verify AMP is enabled/disabled intentionally (Ghost defaults to disabled in v5+)
Open Graph / Twitter Cards	Post social settings	Verify Facebook and Twitter card previews