Technical SEO Audit Checklist [2025]: Complete Guide

Why Technical SEO Matters in 2025

Technical SEO is the foundation that allows search engines to discover, crawl, index, and rank your content. Without solid technical foundations, even the best content may never reach its audience.

In 2025, technical SEO has expanded to include Core Web Vitals, which are direct ranking factors. Page experience signals now matter more than ever.

This checklist provides a systematic approach to auditing and improving your site's technical SEO. Work through each section methodically for comprehensive coverage.

Crawling and Indexing

Before search engines can rank your pages, they must be able to find and index them. Crawling issues are often invisible but can devastate your SEO.

Use Google Search Console to monitor crawl stats, coverage issues, and indexing status. Most crawling problems are easily fixable once identified.

Ensure your most important pages are easily discoverable within three clicks from the homepage. Deep pages with no internal links may never be crawled.

• robots.txt: Verify it doesn't block important content. Test with robots.txt Tester in Search Console
• XML Sitemap: Submit to Search Console, include only indexable URLs, update automatically
• Crawl Budget: For large sites, ensure crawl efficiency. Remove duplicate content, fix redirect chains
• Index Coverage: Check Search Console for excluded pages. Fix errors, review warnings
• Canonical Tags: Set canonical URLs on all pages. Avoid conflicting signals
• Noindex Tags: Verify noindex is only on pages you want excluded. Check meta tags and headers
• Internal Linking: Ensure important pages have adequate internal links. Use descriptive anchor text

Site Speed and Core Web Vitals

Core Web Vitals (LCP, INP, CLS) are now direct ranking factors. Test your pages using MakeWebsite.fast or PageSpeed Insights.

Focus on field data from Chrome User Experience Report (CrUX), not just lab scores. Field data reflects real user experiences and is what Google uses for rankings.

Mobile performance matters most due to mobile-first indexing. Test on real mobile devices, not just desktop emulators. See our mobile vs desktop guide.

• LCP under 2.5 seconds: Optimize images, improve server response, eliminate render-blocking resources
• INP under 200ms: Reduce JavaScript, break long tasks, optimize event handlers
• CLS under 0.1: Set image dimensions, reserve space for dynamic content
• TTFB under 800ms: Use CDN, enable caching, optimize server
• Mobile Performance: Test with throttling, optimize for slower devices
• Resource Optimization: Compress images, minify CSS/JS, use modern formats

Mobile-First Indexing

Google uses mobile-first indexing for all sites, meaning the mobile version of your site is what counts for rankings. Ensure mobile and desktop content parity.

Responsive design is the recommended approach. If using separate mobile URLs (m.example.com), ensure proper annotations and identical content.

Test mobile usability in Google Search Console. Fix any mobile usability errors as they can affect rankings.

• Responsive Design: Use viewport meta tag, flexible layouts, responsive images
• Content Parity: Mobile should have same content as desktop. Hidden content may not be indexed
• Touch Targets: Buttons/links should be at least 48x48 pixels with adequate spacing
• Font Size: Use minimum 16px for body text. Ensure readability without zooming
• Viewport Configuration: Set width=device-width, initial-scale=1
• Mobile Usability: Check Search Console for issues. Fix clickable elements too close together

Security and HTTPS

HTTPS is a ranking factor and essential for user trust. All pages should be served over HTTPS with no mixed content.

Implement proper redirects from HTTP to HTTPS. Use HSTS headers to enforce secure connections. Ensure SSL certificate is valid and properly configured.

Security headers protect users and demonstrate site quality. Implement Content Security Policy, X-Frame-Options, and other protective headers.

• SSL Certificate: Valid, not expired, covers all domains/subdomains
• HTTP to HTTPS Redirects: 301 redirect all HTTP URLs to HTTPS equivalents
• Mixed Content: No HTTP resources loaded on HTTPS pages
• HSTS Header: Enable Strict-Transport-Security to enforce HTTPS
• Security Headers: Implement CSP, X-Frame-Options, X-Content-Type-Options
• Secure Cookies: Set Secure and HttpOnly flags on cookies

Structured Data and Schema Markup

Structured data helps search engines understand your content and can enable rich results in search. Implement relevant schema types for your content.

Use JSON-LD format (recommended by Google) rather than microdata or RDFa. Test with Google's Rich Results Test and Schema Markup Validator.

Don't over-optimize structured data. Only mark up content that actually exists on the page. Misleading structured data can result in manual penalties.

• Organization Schema: Company name, logo, social profiles, contact info
• WebSite Schema: Site name, URL, search action for sitelinks search box
• Breadcrumb Schema: Navigation path for breadcrumb rich results
• Article/BlogPosting: For blog posts and news articles
• FAQ Schema: For FAQ sections to get FAQ rich results
• HowTo Schema: For step-by-step guides and tutorials
• Product Schema: For e-commerce product pages

URL Structure and Site Architecture

Clean, descriptive URLs improve user experience and can help search engines understand page content. Keep URLs short, readable, and keyword-relevant.

Flat site architecture (important pages within 3 clicks of homepage) ensures thorough crawling and distributes link equity effectively.

Avoid URL parameters when possible. If necessary, configure URL parameters in Search Console to prevent duplicate content issues.

• URL Format: Use hyphens, lowercase, descriptive words. Avoid underscores, IDs, session parameters
• URL Length: Keep under 100 characters when possible. Shorter is better
• Site Depth: Important pages within 3 clicks of homepage
• Breadcrumb Navigation: Visual breadcrumbs matching schema markup
• URL Parameters: Minimize usage, configure in Search Console if needed
• Trailing Slashes: Be consistent. Redirect non-canonical version

International SEO (If Applicable)

If targeting multiple countries or languages, proper hreflang implementation is essential. Hreflang tells search engines which version to show in each market.

Hreflang is complex and easy to get wrong. Common mistakes include missing self-referential tags, broken bidirectional links, and incorrect language codes.

Consider using ccTLDs, subdomains, or subdirectories based on your resources and strategy. Each approach has trade-offs.

• Hreflang Tags: Implement correctly with bidirectional linking
• Language Codes: Use correct ISO 639-1 codes (en, es, fr, etc.)
• Region Codes: Use correct ISO 3166-1 Alpha-2 codes (US, GB, DE, etc.)
• X-Default: Set fallback for unmatched languages/regions
• Content Translation: Fully translate, don't auto-translate. Include metadata
• International Targeting: Set in Search Console if using gTLD