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The SEO Issue Guide

235 technical SEO issues, each with its own in-depth guide: what it is, why it hurts rankings, how to fix it, and the best practices around it. The same definitions our scanner enforces — so the guide and the audit never disagree.

Crawlability (22)

Crawlability is whether search engine bots can physically reach and read your pages. Before Google can rank anything, Googlebot has to fetch it: follow links to it, receive a successful response, and parse the HTML. Crawl problems are silent — the page looks fine in a browser while bots hit walls (robots rules, broken chains, server errors, infinite URL spaces). Because everything downstream depends on the crawl, fixing crawlability issues usually unlocks more value per hour than any other SEO work.

Indexability (16)

Indexability is whether a crawled page is allowed into the search index at all. A page can be perfectly reachable and still tell Google to ignore it — through a noindex directive, a conflicting canonical, or an X-Robots-Tag header set by the server. These directives are absolute: one stray meta tag removes a page from search entirely. Indexability issues are the most binary in SEO — the page either can rank or it cannot — which is why they sit at the top of every serious audit.

Metadata (37)

Metadata is how your page introduces itself to search engines and social platforms: the title tag, meta description, canonical URL, Open Graph and Twitter cards. Titles remain one of the strongest on-page relevance signals, and descriptions drive click-through rate from the results page even though they aren't a direct ranking factor. Bad metadata rarely breaks a site — it quietly bleeds clicks on every query where you appear.

Structured data (18)

Structured data (JSON-LD / schema.org) is how you describe your content to machines in their own vocabulary: this is a product with this price, an article by this author, an event on this date. It powers rich results — stars, FAQs, breadcrumbs, product info — which materially raise click-through rates. Invalid or incomplete markup doesn't just miss the enhancement; sustained abuse can earn manual actions, so correctness matters as much as presence.

Content (18)

Content is what actually earns rankings: text that answers the query better than the competition. Search engines evaluate depth, originality, structure (headings), and freshness. Thin, duplicated, or poorly structured content doesn't just fail to rank — it can drag down a domain's overall quality assessment. Every content issue here is ultimately about the same question: does this page deserve to be someone's answer?

Performance (42)

Performance is both a ranking signal (Core Web Vitals) and a conversion multiplier. Google measures real-user loading (LCP), interactivity (INP), and visual stability (CLS) — and slow sites lose visitors before analytics even registers them. Most performance issues concentrate in a few repeat offenders: unoptimised images, render-blocking resources, and third-party scripts. Fixing the top three usually moves the needle more than fixing the next thirty.

Mobile (14)

Google indexes the mobile version of your site — desktop is the afterthought, not the other way round. Mobile issues (missing viewport, tap targets too close, content wider than the screen, intrusive interstitials) directly gate rankings for every query. With most traffic on phones, a mobile problem is not a subset of your audience — it is your audience.

Accessibility (30)

Accessibility overlaps heavily with SEO because both depend on machine-readable structure: alt text, heading hierarchy, labels, contrast. Screen readers and search crawlers consume the same signals. Accessible sites rank better not by special treatment but because the same fixes — descriptive alt attributes, proper headings, real link text — are exactly what search engines parse for meaning. It is also, in a growing number of jurisdictions, the law.

Security (25)

Security issues erode both rankings and trust. HTTPS has been a ranking signal since 2014, and browsers actively warn users away from insecure or mixed-content pages — a warning interstitial is a 100% bounce rate. Missing security headers rarely block indexing, but they widen your attack surface, and a hacked site (injected spam, malicious redirects) can be removed from results entirely. Security is the SEO work you do so you never have to do recovery work.