SEO Auditing

An SEO audit is a structured review of a website to identify the factors affecting its visibility in search results. It is not a single check or a single tool - it is a process that works through several distinct areas, each of which can limit performance for different reasons.

What an audit covers

A complete SEO audit has three components. Most site problems fall under at least one of them.

Technical audit

The technical audit checks whether search engines can find, crawl, render, and index the site’s pages correctly. A technically flawed site can have excellent content and still fail to rank, because the content is not accessible to search engines in the first place.

Key areas: crawl access and robots.txt configuration, page indexation and noindex directives, redirect chains, duplicate content and canonical tag accuracy, page speed and Core Web Vitals, mobile usability, structured data markup, and HTTPS configuration.

Content audit

The content audit assesses the quality and relevance of what is on the pages Google has indexed. Content problems are harder to fix than technical ones because they require editorial work, but they are often the primary reason a technically sound site is not ranking.

Key areas: thin pages with insufficient information to satisfy a query, pages targeting overlapping keywords that compete with each other (keyword cannibalisation), duplicate content across multiple URLs, and pages that have lost rankings over time without obvious technical cause.

Off-page audit

The off-page audit reviews the site’s backlink profile: how many links it has, where they come from, how relevant those sources are, and whether any are potentially harmful. Off-page factors cannot be fixed directly, but they can be managed through outreach, disavow files, and link acquisition.

Key areas: referring domain count and quality, anchor text distribution, toxic or unnatural link patterns, and comparison against competitor backlink profiles.

When to run an audit

Quarterly review: A lightweight check of crawl errors, indexation status, Core Web Vitals, and GSC performance data is enough to catch problems early. Full audits do not need to be quarterly.

After major changes: Site migrations, CMS changes, significant redesigns, and large-scale content restructuring can all introduce technical problems. An audit immediately after go-live confirms nothing was broken in the process.

Before a migration: An audit before a migration establishes a baseline for redirect mapping, identifies existing issues that the migration should not carry forward, and captures current performance data for comparison post-launch.

When rankings drop unexpectedly: A sharp decline in organic traffic is usually traceable to a technical change, algorithm update, or content quality issue. An audit provides the diagnostic framework for finding the cause.

Tools

Google Search Console is the starting point for any audit. The Page Indexing report shows which pages are indexed and why others are not. The Performance report shows queries, clicks, and impressions. Core Web Vitals data comes from real users. It is free and, for indexation and performance data, more reliable than any third-party alternative.

Screaming Frog SEO Spider crawls a site the way Googlebot does, returning status codes, redirect chains, duplicate content, missing meta data, and much more. The free version handles up to 500 URLs; the paid version is uncapped.

Sitebulb is an alternative crawler with a more visual interface, particularly strong for architectural analysis and rendering issues.

Ahrefs Webmaster Tools (free) provides backlink data and the ability to see which keywords a site ranks for, making it useful for both the content and off-page components of an audit.

Google PageSpeed Insights and Lighthouse measure Core Web Vitals and page speed, with field data (real user measurements) and lab data (simulated test conditions).

What to do with findings

The output of an audit should be a prioritised action list, not an exhaustive report of everything wrong. Most sites have dozens of improvable things. The ones worth fixing first are those with the highest impact on crawlability, indexation, and on-page quality.

Fix technical blockers first. A crawl issue that prevents indexation of important pages takes priority over any content improvement. Content improvements only matter if the pages can be found.

Group findings by effort and impact. Quick wins that take little development time and produce clear improvements should come before longer projects. Deprioritise cosmetic issues that do not affect search visibility.

For the full process, see the SEO audit guide.