SEO checks reference
Every monitored crawl runs the checks below on each HTML page in your sitemap.
Findings appear in run reports and deploy diffs when they are new or resolved versus your baseline.
Short “Typical fix” hints in the dashboard come from CheckCatalog in SignalDiff.Shared—update the catalog and this page when adding checks.
On this page
Crawl health
Whether pages can be fetched and internal links resolve. Failures here often block other checks for that URL.
HTTP Status Error
- What it detects
- The page response is not HTTP 2xx (for example 404, 410, or 500).
- Why it matters
- Search engines and users cannot reliably access the page; other on-page checks may not run.
- Typical fix
- Restore the URL, fix routing or server errors, or remove it from the sitemap if it was retired intentionally.
Fetch Error
- What it detects
- The crawler could not retrieve the page (network error, DNS failure, timeout, or TLS problem).
- Why it matters
- The URL is unreachable from the crawl environment, so SEO signals cannot be evaluated.
- Typical fix
- Verify the host is public (or use a customer agent for internal sites), check DNS and firewall rules, and increase timeout if the page is slow.
Broken Internal Link Error
- What it detects
- An
<a href>on the page points to another URL on the same site that returns HTTP 4xx/5xx or a non-2xx status when probed. - Why it matters
- Broken internal links waste crawl budget, hurt user experience, and can dilute link equity.
- Typical fix
- Update or remove the link, fix the target page, or redirect the old URL to the correct destination.
Orphan Page Error Warning
- What it detects
- A crawled HTML page has no incoming internal links from any other page on the site (the homepage is excluded). Error when the page is indexable; Warning when it is marked noindex.
- Why it matters
- Pages with no incoming internal links are hard for users to discover and may rely on the sitemap or external links for crawling.
- Typical fix
- Add internal links from navigation, hub pages, or related content so visitors and crawlers can reach this URL without relying on the sitemap alone.
Links
Internal link graph quality: how pages reach each other and whether those links pass signals.
Incoming Internal Links Warning Info
- What it detects
- Nofollow-only inlinks (Warning), a mix of nofollow and dofollow inlinks, or only one dofollow inlink (Info).
- Why it matters
- Thin or nofollow-only inlinks make a URL harder for search engines to discover and to treat as important.
- Typical fix
- Add more dofollow internal links from relevant pages. Avoid relying only on nofollow links for discovery.
Outgoing Internal Links Info
- What it detects
- The page contains at least one internal
<a>withrel="nofollow". - Why it matters
- Nofollow on internal links withholds crawl signals from those destinations.
- Typical fix
- Use dofollow internal links for pages you want indexed unless nofollow is intentional (login, tracking, or user-generated URLs).
Indexability
Signals that control whether search engines should index a URL and which URL is canonical.
NoIndex Warning
- What it detects
noindexin<meta name="robots">,<meta name="googlebot">, or in theX-Robots-Tagresponse header (includingnone).- Why it matters
- The page asks search engines not to include it in results—often intentional for staging or utility pages, but harmful on pages you want indexed.
- Typical fix
- Remove
noindexfrom production pages that should rank, or keep it and exclude those URLs from the sitemap.
Nofollow Warning Info
- What it detects
nofollow(ornone) in robots meta orX-Robots-Tag. Warning when the page is otherwise indexable; Info when it is also noindex.- Why it matters
- Nofollow tells crawlers not to use links on this page as ranking signals. On a whole page it is unusual unless the URL is intentionally excluded.
- Typical fix
- Remove nofollow from pages that should pass link equity, or keep it on utility pages that should not influence rankings.
Canonical Warning Info
- What it detects
-
Missing
<link rel="canonical">, an emptyhref, or a canonical URL that differs from the crawled URL. Warning for missing or empty; Info when canonical points elsewhere. - Why it matters
- Canonical tags consolidate duplicate or parameterized URLs so search engines know the preferred version.
- Typical fix
- Add a self-referencing canonical on indexable pages, or point duplicates at the primary URL. Confirm cross-domain canonicals are intentional.
Sitemap Error Info
- What it detects
-
A URL appears in your sitemap but is marked
noindex(Error), or an indexable crawled page is missing from the sitemap (Info). - Why it matters
- Sitemaps should contain the URLs you want indexed. Listing a noindex URL, or omitting an indexable URL, sends mixed signals.
- Typical fix
- List every indexable URL in the sitemap, and remove noindex URLs from it so discovery and indexability signals agree.
On-page SEO
Core HTML elements that influence rankings, snippets, and content quality.
Title Error Warning
- What it detects
-
Missing or empty
<title>(Error), or title text shorter than 10 characters or longer than 60 characters (Warning). - Why it matters
- The title is the primary label in search results and browser tabs; missing or poor titles reduce click-through and clarity.
- Typical fix
- Add a unique, descriptive title per page. Aim for roughly 10–60 characters with the main topic and brand where appropriate.
Meta Description Error Warning
- What it detects
-
Missing or empty
<meta name="description">or more than one description tag (Error), or description shorter than 50 or longer than 160 characters (Warning). - Why it matters
- Meta descriptions often appear as snippet text in search results and help users decide whether to click. Multiple tags are ambiguous; crawlers typically use only the first.
- Typical fix
- Keep a single concise summary (about 50–160 characters) that matches page intent and includes a clear value proposition.
Heading H1 Error Warning
- What it detects
-
No
<h1>, an empty<h1>, or whitespace-only H1 text (Error), or more than one<h1>(Warning). - Why it matters
- A single clear H1 helps users and search engines understand the main topic of the page.
- Typical fix
- Use one H1 that reflects the page topic; demote extra top-level headings to H2 or lower.
Heading Hierarchy Warning
- What it detects
- A heading level is used without a preceding parent level (for example
<h3>before any<h2>). - Why it matters
- Logical heading order improves accessibility and makes content structure easier to parse.
- Typical fix
- Nest headings sequentially (H1 → H2 → H3) without skipping levels in the document outline.
Missing Alt Text Warning
- What it detects
<img>elements without analtattribute, or with empty or whitespace-onlyalt. Purely decorative images witharia-hidden="true"orrole="presentation"are skipped.- Why it matters
- Alt text helps search engines understand image content and is shown when images cannot be displayed.
- Typical fix
- Add concise, descriptive alt text to each content image. Use
alt=""witharia-hidden="true"only for purely decorative images.
Low Word Count Warning
- What it detects
- Visible body text below 50 words (navigation, boilerplate, and hidden content are excluded).
- Why it matters
- Very thin pages may struggle to rank for competitive queries and can look incomplete to users.
- Typical fix
- Add substantive copy, merge thin URLs into stronger pages, or use
noindexif the page is intentionally minimal.
Duplicate Title Warning
- What it detects
- The same
<title>text appears on more than one crawled page in the run. - Why it matters
- Duplicate titles make it harder for search engines to distinguish pages and can reduce snippet relevance.
- Typical fix
- Give each indexable URL a unique title that reflects its specific content or intent.
Duplicate Description Warning
- What it detects
- The same meta description appears on more than one crawled page in the run.
- Why it matters
- Repeated descriptions provide little differentiation in search snippets across similar URLs.
- Typical fix
- Write unique descriptions per page, or canonicalize duplicate URLs if they should not exist separately.
Performance
Resource weight that can delay rendering and Core Web Vitals.
CSS File Size Warning
- What it detects
-
An external
<link rel="stylesheet">whose response body is 100 KB or larger (Warning). - Why it matters
- Large render-blocking CSS delays first paint and Largest Contentful Paint, which can hurt rankings and user experience.
- Typical fix
- Split, minify, purge unused rules, and compress stylesheets so each file stays under about 100 KB.
Slow Server Response Warning
- What it detects
- The HTML response (including followed redirects) takes 2 seconds or longer.
- Why it matters
- Slow HTML responses waste crawl budget. AI crawlers in particular may skip or undersample URLs that take too long to return.
- Typical fix
- Reduce TTFB with caching, a faster origin, or a CDN. Aim for responses under about 2 seconds so search and AI crawlers do not skip the page.
Informational
Context about redirects and duplicate URLs—not always problems, but worth reviewing.
Redirect Warning Info
- What it detects
- A 3XX response or followed redirect (Warning, except a single HTTP to HTTPS hop), HTTP to HTTPS on the same host, or a chain of two or more hops (Info).
- Why it matters
- Extra hops waste crawl budget. HTTP URLs in a sitemap should be replaced with the HTTPS destination.
- Typical fix
- Point sitemaps and internal links at the final HTTPS URL. Collapse chains to a single 301, and keep HTTP to HTTPS upgrades as one hop.
Off-Domain Redirect Info
- What it detects
- The sitemap URL redirects to a different registrable domain than the site being crawled.
- Why it matters
- May indicate outdated sitemap entries, cross-domain moves, or tracking redirects that should not be in the sitemap.
- Typical fix
- Update the sitemap to list final indexable URLs on the correct host, or remove URLs that intentionally leave the site.
Duplicate Path Info
- What it detects
- Two sitemap URLs resolve to the same normalized page content (for example trailing-slash or alias URLs).
- Why it matters
- Duplicate URLs can split signals unless canonicalized or redirected to one preferred version.
- Typical fix
- Pick a canonical URL, add 301 redirects or canonical tags, and trim redundant entries from the sitemap.
Social & structured
Tags for link previews on social platforms and machine-readable schema.org data.
Open Graph Warning
og:title,og:type,og:url,og:description, orog:imagemeta tags with non-empty content, or anog:urlthat does not match the canonical URL (or the crawled URL when canonical is absent).og:*properties with accurate title, type, canonical URL, summary, and a suitable preview image. Keepog:urlidentical to the canonical URL.Twitter Card Warning
twitter:card,twitter:title,twitter:description, ortwitter:image.summaryorsummary_large_imagefortwitter:card.Structured Data Info Error Warning
<script type="application/ld+json">blocks: absent markup (Info), invalid or empty JSON, bad root shape, missing@type, unknown types, type range mismatches (Error, schema.org validation), missing Google-required properties (Error, Google rich results), plus missing recommended properties (Warning, Google rich results), unknown properties, or missing@context(Warning, schema.org validation).