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Joshua Gutierrez
Joshua Gutierrez

Posted on • Originally published at axiondeepdigital.com

We Built a Free AI SEO Audit Tool — Here's What We Learned Scanning 500+ Sites

We're Axion Deep Digital, a web development and SEO agency. Six months ago we built DeepAudit AI — a free tool that renders pages in a real Chromium browser, runs 60+ SEO checks, and uses AI to rewrite your meta tags.

Since launch, hundreds of sites have been scanned through it. Here's what we found — and what we built to fix it.


Why We Built It

Every free SEO tool we tried did the same thing: parse raw HTML, give a vague score, and upsell a $99/month plan.

The problems:

  • They don't render JavaScript, so they miss content on React/Next.js/Vue sites
  • They check 10-15 surface-level things and call it an "audit"
  • They tell you what's wrong but never how to fix it

We wanted a tool that works the way Google actually crawls — real browser rendering, real Lighthouse scores, and actual fix snippets you can copy-paste.


What We Found Scanning 500+ Sites

78% have broken or missing meta descriptions

The most common issue. Either the meta description is missing entirely, or it's a generic CMS default like "Just another WordPress site." AI rewrites these in seconds.

65% fail basic accessibility checks

Missing alt text, no skip navigation, poor color contrast, unlabeled form inputs. These aren't just compliance issues — Google factors accessibility into rankings.

71% have no structured data

No Schema.org markup at all. No FAQ schema, no LocalBusiness, no breadcrumbs. This is free real estate in search results that almost nobody claims.

Average Lighthouse performance score: 44

The average small business site scores below 50 on Lighthouse performance. Unoptimized images, no lazy loading, render-blocking scripts. Most don't even know their score.

83% missing at least one security header

HSTS, CSP, X-Frame-Options — most sites ship with none of these. Search engines increasingly factor security signals into trust.

Only 12% have proper internal linking

Orphan pages, broken links, no logical hierarchy. Crawlers can't find what isn't linked.


The Tech Stack

For anyone curious about how we built it:

  • Frontend: Next.js 16, Tailwind CSS, Framer Motion
  • Audit Engine: AWS Lambda with Puppeteer (real Chromium rendering)
  • AI Layer: DeepSeek for meta tag rewrites and action plan generation
  • Performance Data: Google PageSpeed Insights API
  • Security Checks: Mozilla Observatory methodology
  • Report Generation: Puppeteer PDF export, stored in S3 with presigned URLs

The Lambda function spins up a headless Chromium instance, navigates to the target URL, waits for JavaScript to execute, then extracts everything — DOM structure, meta tags, headings, images, links, structured data, security headers, and more.

All 60+ checks are deterministic. AI only comes in at the end to analyze results and generate the rewrite suggestions and action plan.


The 7 Categories We Score

Each site gets a weighted score across:

  1. Technical SEO — HTTPS, canonical URLs, robots.txt, sitemap, structured data
  2. Content & Keywords — word count, keyword density, heading hierarchy, readability
  3. Performance — Lighthouse scores, Core Web Vitals, image optimization
  4. On-Page SEO — title tag, meta description, alt text, internal/external links, Open Graph
  5. Accessibility — contrast, form labels, ARIA landmarks, focus indicators
  6. Security — HSTS, CSP, X-Frame-Options, referrer policy
  7. Site Health — multi-page crawl, broken links, redirect chains

Final score: 0-100 with a letter grade.


What Makes It Different

Real browser rendering. Most tools fetch raw HTML with a simple HTTP request. We spin up Chromium. If your site uses React, Next.js, or any client-side rendering, we actually see your content.

Copy-paste fixes. Every failing check includes the exact HTML, CSS, or server config snippet to fix it. Not "improve your meta description" — the actual rewritten tag you can paste into your <head>.

AI-generated action plan. After all checks run, AI reads every result, your Lighthouse scores, and your keyword data, then generates a prioritized list ranked by revenue impact.

Competitor comparison. Run any two sites side-by-side across all 60+ checks.

No signup. 3 audits per day, no account, no credit card, downloadable PDF report.


Try It

DeepAudit AI — Free AI SEO Audit Tool

Paste any URL and get a full report in under 60 seconds. If you find bugs or have feature requests, drop a comment — we're actively building.

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