What Is a Technical SEO Audit? What It Checks and What It Finds

A while back I started working with a company that had good content and no idea why it wasn't ranking. They'd written real, useful pages. They had a designer who cared. And their traffic just sat there, flat, for months. The marketing lead was convinced it was a content problem and wanted to write more.

It wasn't a content problem. In the first stretch of poking around, I found a chunk of their most important pages were quietly missing from Google's index. The content was great. Google just wasn't being allowed to see it cleanly. That's the pattern I see over and over, and it's the reason a technical SEO audit exists.

This piece is the map. It defines what a technical SEO audit is, lays out the categories of problems an audit checks for, and points you to the deeper write-up on each common issue. I'm not going to teach you how to run one step by step, or re-explain every issue in depth here. The goal is to help you recognize which kind of problem you might have, so you know where to look next.

A technical SEO audit is for a site that's already live and underperforming, where you can't quite explain why. Keep that framing in mind. It'll matter later when we sort out what an audit is and isn't.

What is a technical SEO audit?

A technical SEO audit is a systematic check of whether search engines and AI systems can crawl, index, understand, and trust your site. It's the plumbing, not the content or the keywords. The questions it answers are mechanical: Can Google's crawler reach this page? Once it reaches the page, can it index it? Once indexed, does the page send clear enough signals that Google understands what it's about and who published it?

That framing comes straight from how Google describes its own process. Pages have to be crawled, then indexed, then judged eligible to show with a snippet. A technical SEO audit checks each of those gates and finds where a site is getting stuck.

It helps to contrast it with a content audit, because people mix the two up. A content audit asks whether your pages are good: Is the writing useful? Does it answer the question? Is it better than what's already ranking? A technical SEO audit asks a different question. It assumes the content might be fine and checks whether anything is stopping that content from being found and understood in the first place. You can have the best page in your category and still lose, quietly, because a single line in a robots file is telling Google to look away.

Most "we don't know why we're not ranking" situations are technical, not editorial. Writing more rarely fixes a plumbing problem. It just adds more pages to the pile Google can't see properly.

What does a technical SEO audit check?

This is the part that makes the rest of the work navigable. A technical SEO audit covers a handful of categories, and almost every issue I find falls into one of them. Here's the map.

1. Crawlability and indexing

Can Google's crawler, and the AI bots that ride on the same access, actually reach your pages and index them? This is where robots.txt rules, noindex tags, and crawl budget live, and where the most damaging problems hide, because a page that can't be crawled or indexed can't rank at all. Google is explicit that if a page is blocked by robots.txt, the crawler never even sees a noindex rule, so the controls can interact in ways people don't expect.

2. Site structure and internal linking

Can Google find every page that matters by following links, and does your structure signal which pages are most important? This is where orphan pages and excessive link depth show up. Google's guidance is blunt: every page you care about should have a link from at least one other page on your site.

3. Canonicalization and duplication

Does your site serve the same content at multiple URLs, and are your canonical signals clear about which version is the real one? Duplicate URLs, protocol and www variants, and competing pages all dilute signals that should be consolidated on one page. Google treats a canonical preference as a hint, not a rule, so weak or contradictory signals leave it to guess, and it may not guess the way you'd want.

4. Structured data and entity clarity

Is your machine-readable markup present, valid, and consistent, so search engines and AI systems can understand what your pages and your business actually are? This is schema markup and the broader question of whether your brand reads as one clear entity across your site.

5. Performance and Core Web Vitals

Do your pages load and respond well enough to count as a good page experience? Google defines its thresholds as LCP within 2.5 seconds, INP under 200 milliseconds, and CLS below 0.1. The honest caveat: Google says directly that it "always seeks to show the most relevant content, even if the page experience is sub-par." Core Web Vitals is a tiebreaker, not a ranking killer.

6. Rendering

Is your important content visible to a bot, or trapped behind JavaScript that may never get rendered? Sites built on heavy JavaScript frameworks can hide content behind a rendering queue, and Google warns that a page "may stay on this queue for a few seconds, but it can take longer than that." Some AI crawlers don't render JavaScript at all, which makes this matter more than it used to.

What the audit checks	What can go wrong	Where to read about it
Crawlability and indexing	Pages blocked by robots.txt or noindex; pages dropping out of the index entirely	Deindexing
Site structure and internal linking	Important pages with no internal links pointing to them	Orphan pages
Canonicalization and duplication	Competing pages splitting their own signals	Keyword cannibalization
Structured data conflicts	Markup that contradicts itself and confuses search engines	Schema cannibalization
Entity clarity	AI search getting your business wrong or mixing you up	Entity confusion in AI search
Structured data gaps	Missing or broken markup that should be there	Adding schema
New site or section not indexing	A fresh build Google hasn't picked up yet	Why new websites don't show up
Performance and Core Web Vitals	LCP, INP, or CLS regressed past Google's thresholds	Covered above
Rendering	Content hidden behind JavaScript a bot can't see	Covered above

Keep in mind what this table is. It's a router, not a textbook. Each row names a category and points you to the post that goes deep. The audit's job is to figure out which rows apply to you.

The issues a technical SEO audit turns up most

Across the sites I look at, the same handful of findings come up again and again. Here's the short version of each, with a link to the deeper write-up where the real detail lives.

Pages dropping out of the index. A page that ranked fine last quarter is suddenly gone, and its traffic goes with it. There are a lot of reasons pages drop out of Google's index, from a stray noindex tag to a crawl problem to Google quietly deciding the page isn't worth keeping. This is usually the first thing I check, because it's both common and catastrophic when it hits a page that mattered.

Orphan pages. A page exists, but nothing on your site links to it, so Google has a hard time finding it and almost no way to judge how important it is. Orphan pages are easy to create by accident during a redesign or CMS change, and they underperform for no reason the content itself would explain.

Keyword cannibalization. You have two or three pages all targeting the same query, so instead of one strong page you've got several weak ones splitting the signals. Keyword cannibalization looks like a content opportunity ("let's write more about this topic") and is actually working against you.

Schema cannibalization. Most people think of structured data as something you either have or don't. But markup can also fight itself, where different pages or templates send contradictory signals about what your content and business are. Schema cannibalization is the kind of problem most audits don't even check for, which is why it persists.

Entity confusion in AI search. When AI systems get your business wrong, mix you up with another company, or state something outdated, the root cause is usually that your brand doesn't read as one clear, consistent entity. Entity confusion in AI search has become its own category of finding as more people check what the assistants say about them and don't like the answer.

Structured-data gaps. Sometimes it's simpler: the markup that should be there just isn't, or it's broken. The fix is real work, but it shouldn't require a quarter of dev time. Adding schema is more approachable than the way it usually gets scoped, and missing markup means missing rich-result eligibility and weaker machine clarity.

A brand-new site or section that won't index. You launched something, and weeks later it still isn't showing up. New builds stall for their own reasons, different from the reasons an established page drops out. Why new websites don't show up in search covers the indexation delays and common blockers that catch fresh launches.

Each of these gets a sentence or two here on purpose. The depth lives in the spoke. The point of the pillar is to help you recognize which one you're looking at.

Technical SEO is now also AI visibility (SEO is GEO is AEO)

Here's the part that's changed the stakes on technical work. The same crawl, index, and snippet-eligible gate that governs your blue-link rankings also governs whether you can show up in AI answers.

Google says it directly. In its June 2026 AI optimization guide, the requirement is plain: a page must be indexed and eligible to be shown in Google Search with a snippet to appear in generative AI features. The same guide adds that you need to ensure your content is crawlable, because Google's generative AI models use publicly accessible, crawlable content to learn patterns. There's no separate AI index and no special markup that switches on AI visibility. The gate is the same one it's always been.

So a technical problem that blocks crawling doesn't cost you organic rankings and then, separately, AI visibility. It costs you both at once, from a single root cause. A robots.txt rule left over from staging, a noindex that survived a launch, content trapped behind unrendered JavaScript: each quietly removes you from traditional search and AI answers in the same stroke. SEO is GEO is AEO, because the machine-readability floor is shared.

This pillar owns the technical health side. The strategy for showing up and getting cited in AI answers, the off-site presence, the entity work, the content angle, lives in the generative engine optimization pillar. Put simply: a technical SEO audit makes sure the door isn't locked. GEO is the strategy for what you do once you can walk through it.

Audit, migration, or just monitoring? Which you actually need

People reach for "audit" when they mean three different things. Sorting out which one you actually need saves a lot of wasted effort, so let me draw the lines.

A technical SEO audit is for a live site that's underperforming, and you don't know why. The site's been up. Nothing obvious changed. Rankings are softer than they should be, or a few pages quietly fell off, and you want a systematic diagnosis of what's holding the existing site back. That's the situation this whole piece is about.

A site move is a different job with its own playbook. If you're redesigning, changing domains, or replatforming, you're not diagnosing a stable site. You're managing an event, with its own sequence of what to map, what to redirect, and what tends to break along the way. That work belongs to the website migration pillar, not here. A botched move creates exactly the technical problems an audit finds, but the move itself is its own discipline. Don't run a redesign as if it were an audit, and don't audit your way through a domain change.

Knowing whether SEO is working over time is measurement, not a one-time audit. An audit is a point-in-time diagnosis of what's broken. Whether your visibility is trending up or down is a reporting question, not a technical-diagnosis one. If your monthly reports can't tell you what's actually moving, that's its own fixable problem, and it's the subject of why your agency can't tell you what's working. An audit tells you what's broken. Measurement tells you whether fixing it helped.

If your site should be ranking and isn't, and you can't quite explain the gap, that's exactly the kind of question a technical SEO audit answers. It's one discipline, search and AI visibility together, not a menu of separate checks. If you want to figure out what's actually holding your site back and what to fix first, let's talk. You can see how I approach this kind of work on the services page.

A technical SEO audit doesn't ask whether your content is good. It asks whether anything is quietly stopping search engines and AI systems from ever seeing it.