Technical SEO determines whether search engines can crawl, index, and rank your pages. With Google's 2026 algorithm updates, Core Web Vitals signals carry more weight than ever. This checklist covers the items that move rankings in practice.

Crawlability and indexing

robots.txt: Verify it's not blocking important pages or assets (CSS, JS). Test at yourdomain.com/robots.txt.
XML sitemap: Submit to Google Search Console. Include only canonical, indexable URLs. Exclude paginated pages unless they're truly unique content.
Canonical tags: Every page needs <link rel='canonical'>. Pagination: use ?page=N with canonical pointing to itself, not page 1.
noindex audit: Check for accidental noindex on production pages via Search Console Coverage report.

Core Web Vitals

Google uses field data (Chrome User Experience Report) for ranking. Lab data from Lighthouse doesn't directly affect ranking but correlates strongly. Target:

LCP (Largest Contentful Paint): under 2.5s
INP (Interaction to Next Paint): under 200ms
CLS (Cumulative Layout Shift): under 0.1

See our Core Web Vitals 2026 guide for fixes for each metric.

Structured data (JSON-LD)

Structured data enables rich results (sitelinks, FAQs, breadcrumbs, ratings). Use JSON-LD in a <script type='application/ld+json'> tag, not microdata.

Article: For blog posts — datePublished, dateModified, author
BreadcrumbList: For navigation hierarchy
WebSite: Enables sitelinks search box
Product: For e-commerce — price, availability, reviews

Validate with Google's Rich Results Test before deploying.

hreflang for multilingual sites

For sites with multiple language versions, hreflang tags prevent duplicate content penalties and route users to the correct locale:

<link rel="alternate" hreflang="ko" href="https://example.com/ko/page" />

Include an x-default fallback pointing to your default language
Reciprocal: if page A links to page B, page B must link back to page A
Use canonical + hreflang together correctly — common mistake to mix them up

URL structure

Use hyphens, not underscores: /web-performance not /web_performance
Keep URLs short and descriptive. Avoid query strings in URLs for content pages.
Consistent trailing slash: pick one and 301-redirect the other
HTTPS everywhere — HTTP is a ranking penalty

Meta tags

Title tag: 50–60 characters. Primary keyword near the front. Unique per page.
Meta description: 120–155 characters. Not a ranking factor but affects click-through rate.
Open Graph: og:title, og:description, og:image (1200×630px minimum). Required for social sharing.

Page speed

Enable GZIP/Brotli compression on your server
Set long cache headers for static assets (Cache-Control: max-age=31536000, immutable)
Use a CDN for static assets — reduces latency for global users
Preload LCP image: <link rel="preload" as="image" href="hero.webp" />

Mobile-first indexing

Google indexes the mobile version of your site. Verify in Search Console that mobile usability has no errors. Ensure:

Responsive design (not separate m. subdomain)
Tap targets are at least 48×48px with 8px spacing
Font size is legible without zooming (16px base)

Internal linking

Link to important pages from your homepage and hub pages
Use descriptive anchor text — avoid "click here" or "read more"
Fix broken internal links (404s) — use a crawler like Screaming Frog
Orphaned pages (no internal links) rank poorly — connect them

Image SEO

Descriptive filenames: product-red-sneaker-size-10.webp not IMG_4821.jpg
alt text: describes the image for screen readers and search. Don't stuff keywords.
Use srcset for responsive images so search engines understand you have size variants

Monitoring and measurement

Google Search Console: coverage, performance, Core Web Vitals field data
Google Analytics 4: organic traffic trends, landing page performance
Monthly: run Lighthouse on key pages, check for regressions
Set up alerts for 404 spikes and crawl errors