The Complete Technical SEO Audit Checklist

A technical SEO audit answers one question: can search engines actually crawl, understand, and index your site? You can write the best content on the internet — none of it matters if Google can't find it or your pages take eight seconds to load.

And the data says most sites are getting this wrong. Only about 48% of mobile websites pass all three Core Web Vitals^[1] — meaning more than half the mobile web is failing Google's own performance benchmarks. That's a lot of sites leaving rankings on the table.

This is the checklist I use. Not every item applies to every site, but every site should at least be checked against these categories.

Crawlability

First things first. Can Google get to your pages?

• Robots.txt — Does it exist? More importantly, is it accidentally blocking pages you want indexed? I've seen this happen more than you'd think — a developer adds a disallow rule during staging and nobody removes it at launch.
• XML Sitemap — Submitted to Search Console? Does it include the pages that matter and leave out the ones that don't?
• Crawl errors — Check Search Console. Anything flagged on an important page needs to get fixed.
• Internal link structure — Can someone reach every important page within 3 clicks from the homepage? Are there orphan pages floating around with zero internal links pointing to them?
• URL structure — Clean, descriptive, consistent. No session IDs, no unnecessary nesting, no parameter soup.

Indexability

Google can reach your pages. But will it actually index them?

• Index status — Compare how many pages Google has indexed versus how many actually exist on your site. A big gap means something's wrong.
• Canonical tags — Every page needs one. Watch for conflicting canonicals — they confuse Google and they'll confuse you when you're debugging why a page dropped out of the index.
• Noindex directives — Check whether any important pages are accidentally tagged noindex. It happens.
• Duplicate content — Multiple URLs serving the same content. The usual suspects: HTTP vs HTTPS, www vs non-www, trailing slash vs no trailing slash.
• Thin content — Pages under 300 words of unique content often don't get indexed. Either beef them up or consolidate them into something more substantial.

Core Web Vitals

Google uses these as a ranking signal. They measure what real users actually experience. And they matter more than many people realize — website conversion rates drop by an average of 4.42% for each additional second of load time, and the probability of a bounce increases 106% as page load time goes from 1 to 6 seconds.^[2]

• Largest Contentful Paint (LCP) — Under 2.5 seconds. How fast does the main content appear?
• Interaction to Next Paint (INP) — Under 200ms. When someone clicks a button, does something happen quickly or does the page just sit there?
• Cumulative Layout Shift (CLS) — Under 0.1. Do elements jump around while the page loads? Users notice immediately, and Google penalizes it.

Test mobile and desktop separately. Mobile is almost always worse, and it's what Google actually uses for ranking decisions. With mobile now accounting for over 60% of global web traffic^[3], your mobile performance isn't a secondary concern — it's the primary one.

On-Page SEO Elements

• Title tags — Unique, under 60 characters, primary keyword included. Every single page.
• Meta descriptions — Unique, under 160 characters, written to make someone want to click. Every single page.
• H1 tags — One per page. Descriptive. Includes the primary keyword or topic.
• Image alt text — All meaningful images need descriptive alt text. Decorative images can be left empty.
• Structured data — Schema markup appropriate to your content type: Organization, Article, Product, FAQ, whatever fits. Only 41% of pages use JSON-LD markup^[4] — so implementing it properly is still a genuine competitive advantage.

Security and Infrastructure

• HTTPS — Entire site over HTTPS. No mixed content warnings. 92.6% of the top 100,000 websites now default to HTTPS^[5] — so if you're still on HTTP, you're in a shrinking minority that search engines and browsers increasingly penalize.
• Mobile responsiveness — Test on actual phones, not just by resizing your browser window. They're different experiences.
• Status codes — Zero 5xx errors. Minimize 4xx. Redirect chains should be one hop — not three or four redirects daisy-chained together.
• Server response time — TTFB under 200ms for most pages. If your server is slow, nothing else you do matters much.

Prioritizing Fixes

You will find a lot of issues. That's normal. Don't try to fix everything — prioritize by impact:

1. Critical — Pages blocked from indexing, site-wide security issues, core pages returning errors
2. High — Missing titles on important pages, Core Web Vitals failures, duplicate content problems
3. Medium — Missing meta descriptions, unoptimized images, internal linking gaps
4. Low — Alt text on decorative images, minor redirect chains, cosmetic URL stuff

Handle critical and high first. Getting a perfect score on minor issues while your crawl structure is fundamentally broken is a waste of time.

References

1. HTTP Archive — Web Almanac 2024 (Core Web Vitals / CrUX Data)
2. Cloudflare — Website Performance and Conversion Rates
3. MobiLoud — Mobile Internet Traffic Statistics
4. HTTP Archive — Web Almanac 2024 (Structured Data)
5. W3Techs — HTTPS Default Usage Statistics