A technical SEO audit is the starting point for any serious SEO engagement. Before investing in content or link building, you need to know whether Google can actually reach, render, and understand your pages. This guide walks through the exact 7-step process used on every client site – from checking robots.txt to diagnosing JavaScript rendering problems – with actionable fixes at each stage.
What Is Technical SEO?
Technical SEO covers everything that affects how search engine crawlers discover, access, render, and index your pages. It is distinct from on-page SEO (content and keyword optimization) and off-page SEO (backlinks and authority). While on-page and off-page work drives rankings, technical SEO is the prerequisite – it removes the barriers that prevent search engines from seeing your content at all.
The three pillars of technical SEO are crawlability (can Googlebot reach your pages?), indexability (will Google choose to include those pages in its index?), and renderability (can Google execute your JavaScript and see the same content users see?). Most sites fail on at least one of these, even sites with otherwise strong SEO profiles.
For a complete implementation of these measures, the technical SEO service covers auditing and fixing all issues identified in this guide. If page speed is a primary concern, the website speed optimization service addresses Core Web Vitals in detail.
Step 1: Crawlability Audit
Start with robots.txt. Fetch your site's robots.txt file at yourdomain.com/robots.txt and check for unintended disallow rules. Common mistakes include disallowing the entire site (a single stray Disallow: /), blocking CSS and JavaScript files that Google needs to render pages, or blocking staging subdirectories that were never removed when the site went live.
Next, check your XML sitemap. Your sitemap should list only canonical, indexable pages – not paginated pages, filtered URLs, or pages with noindex directives. Submit your sitemap in Google Search Console under Sitemaps, and check for errors in the coverage report. A sitemap with 200 URLs but only 80 indexed pages is a signal of indexation problems worth investigating.
Run a crawl with Screaming Frog (free up to 500 URLs) or Sitebulb. The crawl will surface: broken internal links (4xx errors), redirect chains longer than 2 hops, pages returning 200 status codes but actually showing error content, and orphaned pages with no internal links pointing to them. Export all 4xx pages and fix or redirect them – broken links waste crawl budget and degrade user experience.
Check your crawl budget if you have a large site (10,000+ pages). Use the URL Inspection tool in Search Console and the "Crawl stats" report under Settings to see how many pages Googlebot is crawling per day. If Googlebot is crawling far fewer pages than your site has, you have a crawl budget problem. Fix it by removing low-value pages (faceted navigation, thin content, duplicate parameter URLs) and improving internal linking to priority pages.
Step 2: Indexability Checks
Use Search Console's Coverage report to understand the state of your index. Focus on these four statuses: Indexed (good), Valid with warnings (investigate each warning), Excluded (understand why each page is excluded – some exclusions are intentional, others are not), and Error (fix these immediately).
Common indexability problems include noindex directives left in place from development, canonical tags pointing to the wrong URL (canonicalizing your main product page to a paginated variant, for example), and conflicting signals (a page with a canonical to URL A but a sitemap entry for URL B – Google's response to conflicting signals is unpredictable).
Check for duplicate content issues by searching Google for a unique phrase from your page (site:yourdomain.com "exact phrase") and see which URL ranks. If you have both www and non-www versions, both HTTP and HTTPS versions, or both trailing-slash and no-trailing-slash versions accessible and indexable, you have a duplicate content problem. Choose one canonical version and 301 redirect all others.
Quick check: Fetch three pages with the URL Inspection tool in Search Console and check the "Page is indexed" status and the "Canonical URL Google selected" value. If Google selected a different canonical than you intended, investigate why.
Step 3: Core Web Vitals
Google's Core Web Vitals are three user experience metrics that directly affect rankings. As of 2026, the three metrics are LCP (Largest Contentful Paint), INP (Interaction to Next Paint, which replaced FID in March 2024), and CLS (Cumulative Layout Shift). These are measured from real user data (CrUX field data) and lab data (Lighthouse). Field data is what counts for rankings.
LCP targets: under 2.5 seconds is good, 2.5–4 seconds needs improvement, over 4 seconds is poor. LCP is almost always a hero image, a large heading, or a video poster frame. The most common causes of poor LCP are: hero images not preloaded, hero images served without a CDN, render-blocking third-party scripts delaying page rendering, and large unoptimized images (PNG/JPEG instead of WebP/AVIF). Check your LCP element using Lighthouse or the Core Web Vitals DevTools panel (Performance insights).
INP targets: under 200ms is good, 200–500ms needs improvement, over 500ms is poor. INP measures responsiveness to user interactions. Common causes of poor INP: heavy JavaScript execution on the main thread, large event handler callbacks, unoptimized React re-renders, and third-party scripts (chat widgets, analytics, ad scripts) blocking the main thread. Fix with code splitting, deferred script loading, and moving heavy computation to web workers.
CLS targets: under 0.1 is good, 0.1–0.25 needs improvement, over 0.25 is poor. CLS measures visual stability – how much page elements shift during loading. Common causes: images and embeds without explicit width/height attributes, web fonts causing FOUT (Flash of Unstyled Text), dynamically injected banners or cookie consent dialogs that push content down, and ads that expand after load. Fix by always setting image dimensions, using font-display: optional or swap, and reserving space for dynamic content.
The SEO optimization service includes a full Core Web Vitals assessment and a prioritized remediation plan for each metric.
Step 4: Structured Data
Structured data (Schema.org markup) tells search engines what your content is about in machine-readable format. Correct structured data is required for rich results (star ratings, FAQ dropdowns, breadcrumbs, product prices) in Google Search, and is increasingly used by AI Overviews and answer engines for content extraction.
The most impactful structured data types by page category: homepage and about pages benefit from Organization and LocalBusiness schema (establishes entity identity). Service pages benefit from Service schema with offers and areaServed properties. Blog posts and articles benefit from Article or BlogPosting schema with datePublished, dateModified, author, and image properties. FAQ pages benefit from FAQPage schema (enables FAQ dropdown rich results). Product pages benefit from Product schema with offers, price, availability, and aggregateRating.
Implement structured data as JSON-LD in a script tag in the page head. JSON-LD is Google's preferred format because it decouples the markup from the HTML structure. After implementation, validate using Google's Rich Results Test at search.google.com/test/rich-results and the Schema Markup Validator at validator.schema.org. Watch for errors that prevent rich results (missing required fields) vs. warnings (optional fields not present).
Step 5: Mobile SEO
Google has used mobile-first indexing for all sites since 2023, which means Google uses the mobile version of your page for indexing and ranking. If your mobile page is missing content that exists on desktop, or if your mobile experience is significantly worse, it will hurt rankings even for desktop searches.
Check mobile rendering using the Mobile-Friendly Test at search.google.com/test/mobile-friendly and the URL Inspection tool in Search Console (click "Test Live URL" and review the rendered screenshot). Common mobile SEO problems include: content hidden in CSS on mobile that exists on desktop (Google may not count this content), font sizes below 12px triggering a "text too small to read" warning, tap targets (buttons, links) closer than 48px apart, and viewport meta tag missing or misconfigured.
Prioritizing and Fixing Issues
A technical SEO audit typically surfaces 20–60 issues. Prioritizing them correctly matters. Use this impact framework: Critical (fix this week) – site not indexable, sitewide noindex directive, broken sitemap, widespread 4xx errors on priority pages, Google selecting wrong canonicals for key pages. High (fix this month) – poor Core Web Vitals on key pages, missing structured data on revenue-driving pages, significant crawl budget waste. Medium (fix this quarter) – redirect chains, orphaned pages, missing canonical tags on low-traffic pages. Low (backlog) – minor structured data warnings, minor CLS issues on non-critical pages.
Document every issue with: the URL affected, the issue type, the current state, the desired state, and the fix instructions. For development teams, this becomes a sprint backlog. For agency clients, it becomes the deliverable roadmap. Re-crawl and re-run PageSpeed Insights after fixes to verify resolution and track progress in Search Console over the following 4–6 weeks.
For ongoing technical SEO support and full audit implementation, the technical SEO service provides both the audit and the fixes as a managed engagement.
