SEO Audit Checklist 2026: What to Check and Why

An SEO audit is the fastest way to find out why your site isn't ranking. Most sites have 5-15 technical issues that silently suppress their search visibility — and fixing them takes less time than writing a single blog post.

This checklist covers every technical SEO item that matters in 2026, including the new AI-answer-engine optimization (AEO) checks that most guides ignore.

#Phase 1: Crawlability and indexability

Before worrying about rankings, make sure search engines can actually find and read your pages.

#Sitemap

Your sitemap is a roadmap for search engine crawlers. Check:

• sitemap.xml exists and returns 200
• All canonical URLs are included
• No 4xx or 5xx URLs in the sitemap
• lastModified dates are accurate (not hardcoded to today)
• Submitted in Google Search Console and Bing Webmaster Tools

Learn more: Google Sitemap documentation

#Robots.txt

Your robots.txt controls what crawlers can access. Common mistakes:

• robots.txt exists and returns 200
• No important pages are blocked (check Disallow rules)
• Sitemap location is declared: Sitemap: https://your-site.com/sitemap.xml
• AI crawlers are allowed (or deliberately blocked — see AEO section below)

Learn more: Google Robots.txt specification

#Canonical tags

Canonical tags tell search engines which URL is the "real" version of a page. Without them, duplicate content can dilute your rankings.

• Every page has a <link rel="canonical" href="..."> tag
• Canonical URL matches the page's actual URL (no trailing slash mismatches)
• Canonical points to the HTTPS version, not HTTP
• No canonical chains (A points to B, B points to C)

Learn more: MDN canonical link element

#Crawl budget

For large sites (10,000+ pages), crawl budget matters. Search engines allocate a finite number of requests per day.

• No excessive redirect chains (max 3 hops)
• No infinite crawl traps (calendar pages, faceted navigation)
• noindex on low-value pages (tag pages, search results, paginated archives)

#Phase 2: On-page SEO

These are the elements on each page that directly influence rankings.

#Title tags

• Every page has a unique <title> tag
• Title is 30-60 characters (Google truncates after ~60)
• Primary keyword appears near the beginning
• Brand name at the end (optional for home page, skip for deep pages)

Learn more: Google title link documentation

#Meta descriptions

• Every page has a unique meta description
• Description is 120-160 characters
• Contains the primary keyword naturally
• Includes a call-to-action or value proposition

#Heading structure

• One <h1> per page (the page title)
• <h2> for major sections, <h3> for subsections
• Keywords appear in headings naturally
• No skipped heading levels (h1 → h3, skipping h2)

#Internal linking

• Every page is reachable within 3 clicks from the homepage
• Important pages have multiple internal links pointing to them
• Anchor text is descriptive (not "click here")
• No orphan pages (pages with zero internal links)

#Images

• Every <img> has an alt attribute
• Alt text describes the image (not keyword-stuffed)
• Images are compressed (WebP or AVIF format preferred)
• Lazy loading is set for below-the-fold images: loading="lazy"

Learn more: MDN image lazy loading

#Phase 3: Core Web Vitals

Core Web Vitals are Google's page experience signals. They directly influence rankings.

#Largest Contentful Paint (LCP)

Target: less than 2.5 seconds.

LCP measures when the largest visible element (hero image, heading, video) finishes rendering.

Common fixes:

• Preload the LCP image: <link rel="preload" as="image" href="...">
• Use a CDN to serve images from edge locations
• Avoid client-side rendering for above-the-fold content
• Compress images to WebP (30-50% smaller than PNG/JPEG)

#Interaction to Next Paint (INP)

Target: less than 200ms.

INP measures how fast the page responds to user interactions (clicks, taps, key presses).

Common fixes:

• Break long tasks into smaller chunks (less than 50ms each)
• Defer non-critical JavaScript (defer or async attributes)
• Use requestIdleCallback for non-urgent work
• Avoid layout thrashing (batch DOM reads and writes)

Learn more: Web.dev INP guide

#Cumulative Layout Shift (CLS)

Target: less than 0.1.

CLS measures visual stability — how much the page layout jumps around as it loads.

Common fixes:

• Set explicit width and height on images and videos
• Reserve space for ads and embeds
• Use font-display: swap for web fonts
• Avoid injecting content above the fold after page load

Learn more: Web.dev CLS guide

#Phase 4: Structured data

Structured data (Schema.org JSON-LD) helps search engines understand your content and enables rich results (FAQ boxes, how-to steps, product ratings).

#Essential schemas

• WebSite with SearchAction — enables sitelinks searchbox
• Organization — company name, logo, social profiles
• Article or BlogPosting — for blog posts and news
• FAQPage — for FAQ sections (generates FAQ rich results)
• SoftwareApplication — for SaaS products (enables app store-like results)

#Validation

• Test with Google Rich Results Test
• No errors in Google Search Console Enhancements
• Structured data matches visible page content (no misleading markup)

Learn more: Schema.org documentation

#Phase 5: AEO (Answer Engine Optimization)

This is the new frontier. AI chatbots (ChatGPT, Claude, Perplexity) now answer millions of queries that used to go to Google. If your site isn't optimized for AI citation, you're invisible to this growing traffic source.

#AI bot access

• robots.txt does NOT block GPTBot, ClaudeBot, or PerplexityBot
• Or: deliberately block them if you don't want AI citation (your choice)

#Citation-friendly content

• Pages have clear, concise answers at the top (AI bots extract the first paragraph)
• Structured data helps AI bots understand your content type
• Statistics and facts are cited with sources (AI bots prefer well-sourced claims)
• Your site has an llms.txt or llms-full.txt file (emerging standard for AI-friendly content)

#Content structure for extraction

• Use descriptive headings (H2/H3) that match common questions
• Include comparison tables (AI bots love tabular data)
• Write definitive statements, not hedged opinions

Learn more: OpenAI GPTBot documentation, Anthropic ClaudeBot documentation, Vergate AEO analysis

#Running the audit

You can check most of these items manually, but automated tools save hours:

Free tools:

• Google Search Console — index coverage, Core Web Vitals, manual actions
• Google PageSpeed Insights — Core Web Vitals from real user data
• Google Rich Results Test — structured data validation

Automated scanners:

• Vergate — one-click audit covering SEO, AEO, security, performance, and accessibility with scored results
• Screaming Frog — deep crawl analysis for large sites

Manual checks:

• curl -I https://your-site.com — verify headers, canonical, redirects
• View page source — check structured data, meta tags, heading hierarchy
• Google site:your-site.com — see what Google has indexed

#Common audit mistakes

#Further reading

• Google SEO Starter Guide — the official baseline
• Web.dev Learn SEO — structured learning path
• Ahrefs SEO Blog — in-depth guides and research
• Vergate SEO and AEO analysis — automated scoring with fix suggestions