SEO Audit Checklist: 200 Points in 10 Categories

Last month I asked 30 independent site owners in an export community: “When was your last full-site SEO audit?” Twenty-seven said “never” or “once at launch.”

SEO isn’t a one-time thing. Google updates its algorithm over 5,000 times per year¹ — ranking #1 today doesn’t mean you’ll hold that spot next month. A site that has never been audited is leaking rankings without knowing it.

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01. The 10 Categories and 200 Checkpoints

Categories are ordered by impact weight — the earlier the category, the more fatal its problems.

#	Category	Items	Auto-checkable	Primary Tool
1	Crawl & Index	25	20	Screaming Frog, GSC
2	Technical Infrastructure	25	18	Screaming Frog, Lighthouse
3	On-Page Optimization	25	15	Screaming Frog
4	Content Quality	25	5 (manual)	Manual review
5	Image SEO	20	10	TinyOpt, Screaming Frog
6	Structured Data	15	10	Schema Validator, GSC
7	Internal Links	20	15	Screaming Frog
8	Backlink Health	15	10 (via GSC)	GSC, Ahrefs
9	Mobile Adaptation	15	10	Lighthouse, GSC
10	Analytics & Tools	15	8	GSC, GA4

Below are the most overlooked, highest-consequence items.

02. Critical #01: robots.txt Blocking the Entire Site

This is a real case from our previous technical SEO article²: a site went live for two months, and Google indexed exactly zero pages. After checking every possible cause, we found one line in the root directory:

Disallow: /

The hosting provider’s default robots.txt was never updated. A one-character error blocked the entire site for 60 days.

How to check: Open https://yourdomain.com/robots.txt and confirm the following aren’t present:

Dangerous Directive	Consequence
`Disallow: /`	Entire site blocked from crawling
`Disallow: /wp-admin/` with default template	Common leftover, not fatal but a red flag
`Sitemap: http://example.com/sitemap.xml`	Sitemap pointing to a demo domain

If your robots.txt contains Disallow: /, Google has never seen your site.

03. Critical #02: Mixed Content — HTTPS Page Loading HTTP Resources

HTTPS certificate installed ≠ site is fully secure. If a single image or script on any page loads over http://, the browser shows a “Not Secure” warning.

Google has treated HTTPS as a ranking signal since 2014³. As of 2024, Chrome blocks all HTTP resources by default. Mixed content equals an automatic penalty.

Resource Type	Risk
Images (`<img>`)	Browser flags the entire page as “Not Secure”
JS/CSS	Browser blocks loading outright — page breaks
Embedded video/fonts	Content won’t render

One-click detection: Screaming Frog → Security → Mixed Content report. Results in seconds.

04. Critical #03: Title Tags Duplicated Across Pages

Last year I audited a B2B site with $20M annual revenue. Four hundred pages. Seven Title templates. Fifty product pages shared one identical Title: “Products — Company Name.”

Google can’t differentiate those pages. It randomly picks a few to rank and ignores the rest.

How to check: Screaming Frog → Page Titles → Duplicate column. A healthy site should be under 5%.

Fix principles:

Page Type	Title Format
Homepage	Core keyword + Brand name
Product page	Product name + 1 key feature + ”\| Brand”
Category page	Category term + “Best \| Top \| Wholesale” + ”\| Brand”
Blog post	Post title (with target keyword) + ”\| Brand”

Every page unique. No exceptions. This is the first law of on-page SEO.

05. Critical #04: Core Pages Missing Canonical Tags

Canonical tags tell Google: “This is the official version of this page.” Without them, Google might choose the wrong version to index — or think you’re publishing duplicate content.

Google’s official guidance: every page should have a self-referencing canonical tag⁴.

<link rel="canonical" href="https://yoursite.com/current-page-url/" />

Common mistakes:

Error	Consequence
All pages missing canonicals	Google decides which version to index — may choose wrong
Canonical pointing to homepage `href="/"`	All pages treated as duplicates of homepage
Canonical pointing to a 404	You’re telling Google your page is dead
Paginated pages canonical → page 1	Pages 2-N will never be indexed

Screaming Frog → Directives → Canonicals. Check the missing and error ratios.

06. Critical #05: Image Sitemap Never Submitted

Many sites submit a page sitemap but never an image sitemap. Consequence: Google never actively crawls your images. Image search traffic: zero.

For e-commerce and image-heavy sites, image search can drive 10-25% of organic traffic⁵.

Checkpoint	How to Verify
Image sitemap generated?	WordPress: Rank Math / Yoast auto-generate. Others: requires plugin or manual creation
Submitted to GSC?	GSC → Sitemaps → check image sitemap submission status
All image URLs HTTPS and accessible?	Spot-check 5-10 image URLs from the sitemap

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07. High Risk #06: Broken Internal Links (404) Wasting Crawl Budget

Google allocates a limited crawl budget to each site daily. If Google spends 30% of that quota hitting 404 pages, 30% of your valid pages don’t get crawled in time.

How to check: Screaming Frog → Response Codes → Client Error (4XX).

Source of Broken Links	Fix
Deleted product page, still linked from category	301 redirect to related category or alternative
Old URL structure changed, no redirects	Batch 301 to new URLs
External links in articles now dead	Update link or remove

Ideally, internal 404 count should be zero. If a page must be removed, give it a 301 destination.

08. High Risk #07: Thin Content Pages (<300 Words)

Google’s Helpful Content System specifically targets “low-quality, non-unique” pages⁶. If your site hosts many sub-300-word pages with no unique value, they drag down the entire site’s quality score.

How to check: Export all page URLs. Manually review word counts. Focus on:

Product pages (many sites have images only, no text)
Tag/archive pages (identical across the site)
Author archive pages (minimal content)

Fix strategy:

Situation	Action
Page has potential but lacks depth	Expand to 500+ words with unique information
Page has zero value (e.g., tag archives)	Add `noindex` tag
Page duplicates another page’s content	Merge content, 301 old URL to new

09. High Risk #08: Mobile Usability Issues

Google has used mobile-first indexing for all sites since 2023⁷. Your desktop version being perfect means nothing if mobile fails.

GSC → Mobile Usability report. Three most common issues:

Issue	Trigger	Quickest Fix
Text too small to read	Font size <12px	Set `font-size: 16px` as baseline
Clickable elements too close	Button spacing <8mm	Increase padding/margin, touch targets ≥48px
Content wider than screen	Non-responsive images or tables	Add `max-width: 100%`

Every mobile usability error is telling Google: “I don’t care about mobile users.”

10. 30-Minute Quick Audit: 20 Must-Check Items

If you only have 30 minutes, follow this sequence:

GSC (5 minutes, 5 items):

Pages report → check “Not indexed” count and reasons
Sitemaps → confirm submission status is “Success”
Core Web Vitals → check mobile and desktop LCP/INP/CLS groupings
Mobile Usability → confirm zero errors
Security Issues → confirm no issues

Screaming Frog quick scan (10 minutes, 5 items):

Response Codes → check 404 and 500 error counts
Page Titles → duplicate Title percentage
Meta Description → missing or duplicate percentage
Canonicals → missing percentage
H1 → pages with missing or duplicate H1

Manual check (10 minutes, 5 items):

yoursite.com/robots.txt → confirm no Disallow: /
Type your domain in browser → confirm HTTPS auto-redirect, no security warning
Open homepage on phone → check load speed and horizontal scrolling
Spot-check 3 core product pages → confirm each has unique Title / H1 / Description
Google search site:yoursite.com → compare indexed count to your total page count

Lighthouse (5 minutes, 5 items):

Performance score ≥70 (mobile)
Accessibility score ≥85
Best Practices score ≥90
SEO score ≥90
Check Opportunities → what’s the single biggest improvement?

11. Automation Approach

With the right tools, you can cover ~160 items automatically. The remaining ~40 require human judgment.

Tool	Items Covered	Cost	Core Capability
Screaming Frog	~120 items	Free (500 URLs) / Paid	Full site crawl
Google Search Console	~40 items	Free	Index status, performance data
Lighthouse	~30 items	Free	Performance and PWA audit
Schema Validator	~15 items	Free	Structured data validation
TinyOpt	~10 image/CSS items	Free	Bulk image compression

Must involve human review: content quality assessment, E-E-A-T signal evaluation, keyword strategy review, backlink quality analysis.

12. The Pattern: Audit for Impact, Not Volume

After a full-site audit, you might find 50-200 issues. The number doesn’t matter. The priority does.

The 80/20 rule applies: 20% of issues cause 80% of ranking loss.

Priority logic:

If Google can't find your pages → clear all crawl and index issues first
If pages are found but not clicked → optimize Title and Description
If clicked but users bounce → check content quality and page speed
If content is good but won't rank → check E-E-A-T signals and backlinks

Start from category 1. If the foundation is broken, nothing else matters.

13. FAQ

Q1: How often should I do an SEO audit?

Full deep audit: quarterly. Light checkup (GSC + spot-check core pages): monthly. Immediately after any technical change (domain migration, redesign, theme switch).

Q2: Can I audit without a technical background?

Yes. At minimum, complete the “Manual check 5 items” and “GSC 5 items” from Section 10 — no technical background needed. Technical sections can be handed off to a developer.

Q3: I found 100 issues. Which do I fix first?

Fix “blocker-class” issues first: robots.txt errors, site-wide noindex, expired HTTPS certificate, Sitemap submission failure. These make every other fix irrelevant.

Q4: Do I need paid tools for an audit?

No. Screaming Frog’s free version scans 500 URLs — enough for small sites (<100 pages). GSC and Lighthouse are entirely free. Paid tools improve efficiency but don’t change your ability to find core problems.

Q5: How do I convince a client or boss to invest in SEO fixes?

Don’t use SEO jargon. Use their language: “When people search for [your core product term], Google isn’t showing your site. Your competitor occupies that spot. Fix this, and expect to see traffic changes within X weeks.”

14. Summary

Start with Category 1 — Crawl & Index. A page Google can’t see doesn’t exist.

You don’t need to check all 200 items in one sitting. Round one: clear the 8 critical items. Then rotate through categories monthly, covering all 10 within a quarter.

An SEO audit isn’t a test with a passing score. It’s a map — showing you where rankings are leaking and which hole to plug first.