Technical SEO: A Complete Checklist for a Fast, Well-Structured Site

Core Web Vitals, crawlability, schema markup, sitemaps: everything you need to know about technical SEO, with a complete checklist to get your site's foundations in order.


Technical SEO: A Complete Checklist for a Fast, Well-Structured Site

Technical SEO is the least visible part of optimisation work, but it's the part everything else relies on. You can have the best content on the web, but if your site is slow, poorly structured, or hard for search engines to crawl, all that effort goes to waste.

In this article, we cover the technical aspects that genuinely matter, without unnecessary jargon. The goal is to give you a concrete checklist you can use to audit and improve your site.

Why Technical SEO Matters

Think of technical SEO as a building's foundations. You can't see them, but without them, nothing stands.

Search engines need to:

1. Find your pages (crawling)
2. Understand what they're about (rendering and indexing)
3. Evaluate the quality of the experience you offer (performance and UX)

If any of these steps fails, you have a problem. And the beauty of technical SEO is that, once fixed, it tends to stay fixed — unlike content that requires ongoing updates.

Core Web Vitals: The Performance Metrics

Core Web Vitals are the metrics Google uses to measure your site's user experience. They're a confirmed ranking factor.

LCP (Largest Contentful Paint)

What it measures: how long it takes to load the largest visual element on the page.
Target: under 2.5 seconds.
How to improve it:

  • Optimise images (WebP/AVIF format, appropriate dimensions)
  • Use a CDN to serve content faster
  • Implement lazy loading for below-the-fold images
  • Minimise render-blocking CSS and JavaScript

INP (Interaction to Next Paint)

What it measures: how long it takes for the page to respond after a user interaction (replaced FID).
Target: under 200 milliseconds.
How to improve it:

  • Reduce the amount of JavaScript executed during interactions
  • Break long tasks into smaller ones
  • Use web workers for heavy operations

CLS (Cumulative Layout Shift)

What it measures: how much page elements move during loading.
Target: under 0.1.
How to improve it:

  • Always specify dimensions for images and videos (width and height)
  • Reserve space for ads and embeds
  • Avoid inserting dynamic content above already-visible content

Crawlability: Let Search Engines Find You

If Google can't crawl your pages, you simply don't exist for the search engine.

Robots.txt

The robots.txt file tells crawlers which parts of your site they can explore. Verify that:

  • You're not accidentally blocking important pages
  • CSS and JS resources needed for rendering aren't blocked
  • The file is accessible at yoursite.com/robots.txt

XML Sitemap

The sitemap is your site's map for search engines:

  • Include it in your robots.txt
  • Submit it through Google Search Console
  • Ensure it contains only canonical URLs and pages with 200 status
  • Update it automatically when you add or remove pages

Site Structure

  • Every important page should be reachable within 3 clicks from the homepage
  • Use a logical hierarchical structure: Homepage > Categories > Specific Pages
  • Implement breadcrumbs to help users and engines navigate

Crawl Errors

Regularly check Google Search Console for:

  • 404 errors: pages that no longer exist (create 301 redirects where appropriate)
  • 5xx errors: server problems preventing access
  • Blocked pages: content you've unintentionally made inaccessible

Mobile-First: It's No Longer Optional

Google indexes the mobile version of your site first. If the mobile version is lacking, your rankings suffer.

Points to verify:

  • Design is responsive and works across all devices
  • Fonts are readable without zooming (minimum 16px for body text)
  • Buttons and links are large enough to tap easily (minimum 48x48px)
  • Content doesn't overflow the screen
  • No intrusive pop-ups covering the main content

HTTPS and Security

HTTPS has been a ranking factor since 2014. If your site is still on HTTP, this is the first thing to fix.

Security checklist:

  • Valid, up-to-date SSL certificate
  • All resources (images, scripts, CSS) served via HTTPS
  • 301 redirect from HTTP to HTTPS configured
  • No mixed content (HTTP resources on HTTPS pages)

Schema Markup: Speak the Engines' Language

Structured data (schema markup) helps search engines understand the context and content type of your pages. It's not a direct ranking factor, but it improves presentation in results and increases CTR.

Essential schemas:

  • Organization/LocalBusiness: who you are, where you are, how to contact you
  • Article/BlogPosting: for blog posts (author, date, category)
  • FAQ: for frequently asked questions sections
  • HowTo: for step-by-step guides
  • BreadcrumbList: for breadcrumb navigation
  • Product: for product pages (price, availability, reviews)

Useful tools:

  • Schema.org for documentation
  • Google Rich Results Test for verifying implementation
  • Google Search Console for monitoring structured data

Site Speed: Practical Tips

Beyond Core Web Vitals, here are additional interventions for improving speed:

  • Compression: enable Gzip or Brotli on the server
  • Browser caching: set appropriate cache headers for static resources
  • Minification: minify CSS, JavaScript, and HTML
  • Preconnect and preload: load critical resources in advance
  • Remove unused resources: strip out scripts, CSS, and plugins you no longer use

Internationalization (hreflang)

If your site is available in multiple languages — like ours, in Italian, English, and French — hreflang tags are essential:

  • They tell Google which language version to show to which audience
  • They prevent duplicate content issues between language versions
  • They must be bidirectional (if the EN page points to FR, FR must point back to EN)

Complete Technical SEO Checklist

Here's the full summary checklist:

Performance

  • [ ] LCP < 2.5 seconds
  • [ ] INP < 200 milliseconds
  • [ ] CLS < 0.1
  • [ ] Gzip/Brotli compression enabled
  • [ ] Browser caching configured
  • [ ] CSS and JS minified

Crawlability

  • [ ] Robots.txt correct and accessible
  • [ ] XML sitemap updated and submitted to Search Console
  • [ ] No 404 errors on important pages
  • [ ] Site structure with maximum 3 levels of depth
  • [ ] Breadcrumbs implemented

Mobile

  • [ ] Responsive design
  • [ ] Readable fonts on mobile
  • [ ] Appropriately sized touch elements
  • [ ] No intrusive pop-ups

Security

  • [ ] HTTPS active with valid certificate
  • [ ] No mixed content
  • [ ] 301 redirect from HTTP to HTTPS

Structured Data

  • [ ] Organization/LocalBusiness schema
  • [ ] Article schema for blog posts
  • [ ] FAQ schema where appropriate
  • [ ] BreadcrumbList schema
  • [ ] Validated with Rich Results Test

Internationalisation

  • [ ] Correct, bidirectional hreflang tags
  • [ ] Sitemap with alternate language URLs

Ongoing Maintenance

Technical SEO isn't a one-off activity. Set up a regular audit schedule:

  • Weekly: check for errors in Search Console
  • Monthly: review Core Web Vitals and speed
  • Quarterly: complete technical audit

Technical issues tend to accumulate silently. Regular checks let you intervene before they become critical.

In the next article, we tackle a topic that ties everything together: how to create content that ranks on both Google and generative AI.

Want a technical check of your site? Our free analysis tool evaluates performance and shows you where to improve.