Here’s a comprehensive, action-oriented on-page SEO audit checklist organized by priority. You can run this manually or with tools like Screaming Frog, Sitebulb, or Ahrefs Site Audit.

Phase 1: Technical Foundation (Fix First)

These block rankings if broken.

• Indexability Status

  • Check robots.txt isn’t blocking important pages
  • Verify no rogue noindex tags on money pages
  • Confirm canonical tags are self-referencing (or correctly pointing to canonical URL)
  • Check for index bloat (thin pages indexed: tags, archives, parameters)

• Core Web Vitals (Use PageSpeed Insights + CrUX)

  • LCP < 2.5s
  • INP < 200ms (or FID < 100ms if still tracking)
  • CLS < 0.1
  • Action: Prioritize above-the-fold render-blocking resources

• Mobile-First Reality Check

  • Test on actual mobile device, not just emulator
  • Check tap targets (minimum 48px)
  • Verify no hidden content behind "Read more" on mobile (Google discounts this)
  • Check viewport configuration

• Crawl Efficiency

  • Flatten architecture: Important pages within 3 clicks from homepage
  • Check for crawl traps (infinite faceted navigation, calendar pages)
  • Orphan pages identification (pages with 0 internal links)

Phase 2: Content Quality & Keyword Alignment

• Search Intent Match

  • Pull top 3 ranking competitors for target keyword
  • Compare content angle: Are they listing products? Explaining concepts? Providing tools?
  • Mismatch = rewrite. Informational query needs education, not sales pitch.

• Topical Authority Depth

  • Does page cover subtopics that ranking pages include? (Use TF-IDF analysis or Clearscope/SurferSEO)
  • Word count isn’t the metric—concept coverage is. Aim for comprehensive, not fluffy.

• Keyword Cannibalization Audit

  • Search: site:yourdomain.com "target keyword"
  • If multiple pages rank for same term, consolidate (301 redirect weaker to stronger) or differentiate intent clearly

• E-E-A-T Signals

  • Author bio with credentials (YMYL topics critical)
  • "Last updated" date visible and actually updated
  • External citations to authoritative sources (not just Wikipedia)
  • About/Contact pages easily accessible

Phase 3: On-Page HTML Elements

Use Screaming Frog or similar to bulk export these.

• Title Tags (High Impact)

  • Length: 50-60 characters (pixel width matters more—keep under 580px)
  • Front-load primary keyword
  • Unique across site (no duplicates)
  • Include brand at end (separator: | or -)
  • CTR Optimization: Add benefit-driven modifiers ("2024," "Free," "Step-by-Step")

• Meta Descriptions

  • Length: 120-158 characters (mobile often truncates at 120)
  • Active voice with clear value proposition
  • Include primary keyword (bolded in SERPs if it matches query)
  • Unique per page—no templates auto-generating duplicates

• Header Hierarchy (H1-H6)

  • One H1 per page (logically the main headline)
  • H1 includes primary keyword (natural variation acceptable)
  • Logical outline structure (don’t skip H2→H4)
  • Headers formatted as questions or benefits, not just keywords

• URL Structure

  • Short, descriptive, hyphen-separated
  • No parameters/session IDs in final URL
  • HTTPS enforced
  • No dates in URLs for evergreen content (prevents looking stale)

Phase 4: Media & Structured Data

• Image Optimization

  • File size: <100KB per image (use WebP format)
  • Descriptive filenames: red-leather-office-chair.jpg not IMG_0034.jpg
  • Alt text: Descriptive for accessibility, include keyword only if natural
  • Dimensions specified in HTML to prevent CLS shifts
  • Lazy loading implemented for below-fold images

• Schema Markup (JSON-LD)

  • Article/BlogPosting schema for content
  • Product schema with price/availability (commerce)
  • FAQ schema (if applicable—high CTR win)
  • BreadcrumbList schema
  • Validate at: https://validator.schema.org/

Phase 5: Internal Linking & UX

• Contextual Internal Links

  • 3-5 internal links per 1,000 words (minimum)
  • Anchor text varied but descriptive (avoid "click here")
  • Link to pillar content from cluster pages (and vice versa)

• Navigation & Site Architecture

  • Breadcrumbs implemented (especially for e-commerce/categories)
  • Footer links present but not spammy
  • Main nav uses text links, not JavaScript-dependent menus

• User Engagement Signals

  • Time on page analysis (GA4): If <30 seconds, content mismatch
  • Scroll depth tracking: If <50%, move CTA/Hook higher
  • Broken internal/external links check (404 errors)

Quick-Win Priority Matrix

Do today:

1. Fix title tags >60 characters or duplicates
2. Add/update meta descriptions on top 20 traffic pages
3. Fix any 404s from internal links

Do this week: 4. Consolidate cannibalizing content 5. Compress images >100KB 6. Add/update Schema markup

Do this month: 7. Internal linking overhaul 8. Content depth expansion for positions 4-10 keywords 9. Core Web Vitals optimization

Which stage are you at right now? Are you auditing a brand new site, troubleshooting a traffic drop, or optimizing specific landing pages? Also, what tools do you currently have access to (Screaming Frog free/paid, Ahrefs, SEMrush, just Search Console)? I can help you prioritize which checks will give you the biggest ROI based on your specific situation and tool stack.

On-Page SEO Audit Checklist for 2026

This checklist is compiled from the latest 2026 best practices (e.g., Semrush, Ahrefs, WordStream, Loganix), emphasizing Core Web Vitals, mobile-first indexing, AI crawler access (for ChatGPT/Perplexity visibility), user intent matching, E-E-A-T (Experience, Expertise, Authoritativeness, Trustworthiness), and helpful content for both traditional SERPs and AI overviews.

Preparation Steps:

1. Set up tools: Use free ones like Google Search Console (GSC), PageSpeed Insights, Mobile-Friendly Test, and Lighthouse. For deeper audits: Semrush Site Audit, Ahrefs Site Audit, or Screaming Frog (free up to 500 URLs).
2. Crawl your site: Run a site crawl to scan all pages. Export issues by category (e.g., titles, headings).
3. Target pages: Prioritize top pages by traffic (from GSC) or revenue potential.
4. Keyword research: Use Semrush Keyword Magic Tool or Ahrefs Keywords Explorer to confirm target keywords, intent, and top competitors.

Audit Checklist (Check off as you go; fix high-priority issues first like crawl blocks or slow speed):

1. Crawlability & Indexability

• Robots.txt allows key crawlers: Check yoursite.com/robots.txt. Ensure no Disallow: / for Googlebot, Bingbot, OAI-SearchBot (ChatGPT), PerplexityBot. Fix: Remove blocks; test with GSC URL Inspection.
• No unintended noindex/nofollow: Scan for <meta name="robots" content="noindex">. Only use on thin pages. Fix: Remove from important pages.
• Canonical tags: Each page has <link rel="canonical" href="..."> pointing to itself (no duplicates). Fix: Add via CMS plugin (e.g., Yoast).
• XML sitemap submitted: Verify in GSC; includes key pages only.

2. Title Tags & Meta Descriptions

• Unique titles: 50-60 chars, primary keyword front-loaded (e.g., "On-Page SEO Checklist 2026 | Actionable Tips"). No duplicates >80%. Check: Crawler report; Fix: Edit in CMS/head.
• Compelling meta descriptions: 150-160 chars, keyword early, benefits/CTAs (e.g., "Boost rankings with this 2026 checklist... Download free!"). Check: GSC SERP preview; Fix: Add unique ones.

3. Headings & Structure

• One H1 per page: Matches title, includes primary keyword. Check: View page source.
• Hierarchical headings: H2-H3 for sections (e.g., H2: "Keyword Research Steps"), keywords naturally. No skips (H1 to H4). Fix: Use short, scannable headers.
• Table of contents: For long pages (>1,500 words); use jump links.

4. URL Structure

• SEO-friendly: Short (<100 chars), descriptive, hyphens (e.g., /on-page-seo-audit-checklist-2026), keyword-rich, no dates/parameters. Fix: 301 redirect old URLs.

5. Content Optimization

• Matches intent: Analyze top 10 SERP pages; cover all angles (answer main question in first 100-200 words). Check: Semrush SEO Content Template.
• Keyword integration: Primary in intro/H1, natural density (1-2%), LSI terms/variations. No stuffing.
• Quality & E-E-A-T: 1,500+ words for depth, original, factual, expert-backed (author bio, sources). Readability: Short sentences/paragraphs (Flesch >60). Fix: Use Grammarly/SEO Writing Assistant.
• Freshness: Update dates/stats/links annually. Check: Last modified in GSC.

6. Images & Media

• Optimized: Compress (<100KB, WebP format), descriptive filenames (e.g., on-page-seo-checklist-2026.png). Tool: TinyPNG.
• Alt text: Keyword-relevant, descriptive (e.g., "2026 on-page SEO audit checklist infographic"). 100% coverage.

7. Links

• Internal links: 3-5 per page, descriptive anchors to relevant pages (boosts authority flow). Fix: Add from high-traffic pages.
• External links: 2-3 to high-DA sites (nofollow if sponsored). No broken links (check crawler).

8. Schema Markup (Structured Data)

• Implemented: Use JSON-LD for Article, FAQ, HowTo, Product, LocalBusiness. Test: Google's Rich Results Test. Add: Schema.org generator.

9. Technical Performance

• HTTPS: Secure site-wide.
• Page speed/Core Web Vitals: LCP <2.5s, INP <200ms, CLS <0.1 (mobile/desktop). Check: PageSpeed Insights; Fix: Lazy-load images, minify JS/CSS, CDN.
• Mobile-friendly: Responsive, tappable elements. Test: Google's Mobile-Friendly Test.

10. UX & Engagement Signals

• Readability/Accessibility: High contrast, keyboard nav, no layout shifts.
• Above-fold CTA: Clear next step (e.g., "Download checklist").
• Entities for AI: Mention specific brands/topics; conversational tone.

Post-Audit Actions:

1. Prioritize fixes: Errors > Warnings (e.g., via Semrush/Ahrefs reports).
2. Re-crawl & monitor: Submit updated sitemap to GSC; track in 2-4 weeks.
3. Test changes: Use GSC URL Inspection > "Test Live URL".

This checklist can boost rankings by 20-50% on optimized pages (per Semrush studies). Download free templates from Semrush/WordStream for spreadsheets.

What specific page or website are you auditing first? Do you have access to tools like Semrush or GSC, and what's your niche/industry for tailored advice?