SEO Audit
An SEO audit is a systematic review that diagnoses the technical, on-page, content, and backlink problems holding back a site's search performance. It examines crawling, indexing, speed, tags, and links to surface issues and prioritize fixes by their impact.
- An SEO audit diagnoses search performance across the board, covering crawling, indexing, Core Web Vitals, on-page elements, content, and backlinks.
- It is broader than a content audit, which only evaluates content quality; an SEO audit examines the entire site.
- Ahrefs Site Audit checks for 170+ technical and on-page issues, while Semrush Site Audit covers roughly 100.
- Findings are graded by site health score and by error, warning, and notice severity, then tackled in order of impact.
- The recommended sequence is staged: fix critical technical problems such as crawling, indexing, and broken pages first, then address content and backlinks.
Overview
An SEO audit is a diagnostic exercise that systematically uncovers the problems keeping a site from performing in search, spanning the technical, on-page, content, and backlink areas. In a single pass it checks whether crawlers can reach pages, whether indexing works correctly, whether pages load quickly, whether titles, meta tags, and headings are optimized, whether content matches search intent, and whether the external link profile is healthy, then translates the findings into a list of fixes.
It is often confused with a content audit, but the two differ in scope. A content audit evaluates the performance, quality, and duplication of individual pieces of content, whereas an SEO audit is a wider review that diagnoses the search health of the entire site, including content but also server configuration, crawling, indexing, speed, structured data, and links.
Areas Reviewed
Crawling and Indexing
Whether search engines can read and index the site is the most basic concern. Check that robots.txt is not blocking important crawlers, that no pages are dropped from the index by noindex, that the site is not duplicated across HTTP/HTTPS and www variations, and that sitemap.xml is valid. This stage also catches 404 errors, redirect chains, and orphan pages (pages with no internal links). The Semrush guide recommends that important pages be reachable within three clicks of the homepage.
Core Web Vitals and Speed
Review loading speed and Core Web Vitals, the user-experience metrics. The thresholds Semrush recommends are LCP under 2.5 seconds, INP under 200ms, and CLS under 0.1. Use the Core Web Vitals report in Google Search Console as a starting point, and verify mobile-friendliness as well.
On-Page
Check the page-level optimization elements. Review the SEO title, meta description, heading structure starting with the H1, URL structure, and keyword usage against best practices. Missing or duplicate titles and meta descriptions are common findings.
Content
Assess whether content satisfies search intent, whether any pages are declining in performance, whether there are content gaps on topics competitors cover but you do not, and whether keyword cannibalization or weak E-E-A-T is present.
Internal Links and Backlinks
Check that the internal link structure passes authority effectively to important pages, and analyze the backlink profile for link quality, topical relevance, and growth trend. Ahrefs Site Explorer or Webmaster Tools can be used to analyze backlinks and internal linking opportunities.
Tools and Prioritization
The leading tools combine Google Search Console (index status, mobile usability, manual actions, and the Core Web Vitals report) with commercial crawlers. Ahrefs Site Audit automatically checks for 170+ technical and on-page issues, and Semrush Site Audit checks for roughly 100 problems, including broken links, redirects, slow pages, HTTPS, missing meta tags, and structured data errors.
Rather than fixing every finding indiscriminately, you prioritize them. Semrush quantifies overall health with a Site Health score and sorts issues into Errors, Warnings, and Notices. The recommended order of operations is as follows.
| Stage | Target | Timing |
|---|---|---|
| Stage 1 | Crawl and index blocks, broken pages, critical technical errors | Immediate |
| Stage 2 | Content quality, keyword gaps, high-traffic pages | Next |
| Stage 3 | Backlinks, brand mentions, AI visibility | Ongoing |
Ahrefs sorts issues by estimated organic traffic, recommending that you fix problems on high-value pages first. An SEO audit is best repeated quarterly or twice a year to keep site health under continuous management.
Execution Checklist
- Check robots.txt and noindex settings to confirm important pages are not dropped from crawling or indexing.
- Consolidate the site into a single canonical version so HTTP/HTTPS and www variations do not create duplicates.
- Use a crawl to find and fix sitemap.xml validity issues, 404 errors, redirect chains, and orphan pages.
- Verify Core Web Vitals (LCP under 2.5s, INP under 200ms, CLS under 0.1) and mobile-friendliness.
- Clean up missing or duplicate on-page elements such as titles, meta descriptions, H1s, and URL structure.
- Identify and improve declining content, content gaps, and keyword cannibalization.
- Analyze the internal link structure and the quality and relevance of backlinks.
- Prioritize findings by site health score, error severity, and traffic impact, and work through them in stages.