If you're looking for the wider context (technical and content SEO together), see the pillar page on website SEO audits online. This page focuses purely on the technical side.
Canonical URL
Canonical tells the search engine which URL is the "original". The most common problems: canonical points to a different (nonexistent or redirected) URL, is missing entirely, or is the same on every page. An incorrect canonical can quietly drop pages out of the index.
Status codes and redirects
- 200 — the page works and should be indexable.
- 301 — permanent redirect; use it to consolidate website versions.
- 302 — temporary; don't use it where a 301 belongs.
- 404 / 410 — nonexistent pages; they must not be in the sitemap or the target of internal links.
- Redirect chains — A→B→C wastes crawl budget for nothing, shorten them to a single hop.
Robots.txt
Robots.txt must not block important sections of the site or the CSS/JS needed to render it. It should
reference sitemap.xml. Watch out: Disallow in robots.txt is not a deindexing tool — that's
what noindex is for.
Sitemap.xml
The sitemap should contain only canonical, indexable URLs with a 200 status — no 404s, redirects or
noindex pages. It should be up to date and available at a stable address.
Broken links
Internal links leading to 404/500 are a sign of a low-quality site and hurt how search engines crawl the page. The audit tests every internal link and flags the broken ones.
Heading structure
One H1 per page that captures the topic, and a logical H2/H3 hierarchy. Skipping levels or having multiple H1s makes it harder for search engines to understand the content.
Core Web Vitals
| Metric | What it measures | Good value |
|---|---|---|
| LCP | Main content load | < 2.5 s |
| CLS | Layout stability (content jumping) | < 0.1 |
| INP | Interaction responsiveness | < 200 ms |
Security headers
HTTPS with a valid certificate is a given. On top of that come headers like
Strict-Transport-Security, X-Content-Type-Options, X-Frame-Options
and Content-Security-Policy — they increase trust and website security.
Structured data
Valid JSON-LD (Organization, WebSite, BreadcrumbList, FAQPage etc.) helps search engines understand content more precisely. The audit checks whether the schema is syntactically broken or contradicts what's actually visible on the page.
Frequently asked questions
What is a technical SEO audit?
A check of the technical signals of a website that determine whether search engines can crawl and index it: status codes, canonical, redirects, robots.txt, sitemap, broken links, headings, Core Web Vitals, security headers and structured data.
Why is a technical website check more important than content?
Even the best content is invisible if the page is blocked by noindex, a bad canonical or robots.txt. Technical signals are a prerequisite for content to get into the index at all.