07 / Crawl
Beyond crawlability and on-page tags, every audit checks structured data, image alt attributes, server response time, accessibility basics and HTTPS security, each with its own category score.
These five categories each have their own score, so a site can see at a glance whether its weak spot is markup, media, speed, accessibility or security. Every issue explains why it matters and how to fix it.
1. Structured data (JSON-LD)
Structured data helps search engines and AI assistants understand entities on a page, such as products, articles, organizations and FAQs, and makes pages eligible for rich results.
OpportunityNo structured data
Structured data helps search and answer engines understand entities on the page and can enable rich results.
How to fix: Add relevant JSON-LD such as Organization, Article, Product, LocalBusiness, BreadcrumbList or FAQPage.
WarningInvalid JSON-LD
At least one JSON-LD block could not be parsed, so search engines will ignore it.
How to fix: Fix the JSON syntax and validate the markup with the Rich Results Test or the Schema.org validator.
2. Image alt text
Alt text describes images to screen readers and gives search engines context for image search. The URL details panel lists every image on a page with its alt attribute.
WarningImages missing alt attribute
Alt text describes images to screen readers and search engines, and is used by image search.
How to fix: Add descriptive alt text to meaningful images and alt="" to purely decorative ones.
3. Performance
Response time is measured for every URL during the crawl. Slow responses usually point to a slow template, a heavy database query or missing caching, so group slow URLs by section to find the cause.
WarningSlow response (over 1 second)
The HTML took more than one second to download. Slow server responses hurt Core Web Vitals and crawl rate.
How to fix: Improve server response time with caching, a CDN, database tuning or better hosting.
OpportunityLarge HTML (over 500 KB)
Heavy HTML takes longer to download and parse, especially on mobile connections.
How to fix: Remove inline bloat such as embedded data, repeated markup and large inline scripts or styles.
4. Accessibility basics
WarningMissing lang attribute
The html lang attribute tells screen readers and search engines which language the page uses.
How to fix: Add lang to the html element, for example <html lang="en">.
WarningMissing viewport meta tag
Without a viewport tag the page will not render properly on mobile devices, which affects mobile-first indexing.
How to fix: Add <meta name="viewport" content="width=device-width, initial-scale=1">.
5. HTTPS and security headers
CriticalPage served over HTTP
Pages without HTTPS are flagged as not secure by browsers, and HTTPS is a ranking signal.
How to fix: Serve the page over HTTPS and 301 redirect the HTTP version.
WarningMixed content
An HTTPS page loads resources over HTTP. Browsers may block them and show security warnings.
How to fix: Load every resource over HTTPS.
OpportunityMissing HSTS header
Strict-Transport-Security forces browsers to always use HTTPS, preventing downgrade attacks.
How to fix: Add a Strict-Transport-Security header, for example max-age=31536000; includeSubDomains.
6. How these categories are weighted
| Category | Weight in overall score |
|---|---|
| Performance | 1.0 |
| Security | 1.0 |
| Accessibility | 0.7 |
| Images | 0.6 |
| Structured Data | 0.6 |
For comparison, Technical SEO weighs 1.5 and On-Page SEO 1.2. See Site Health score for the full formula.
Frequently asked questions
Does SiteAuditLint validate schema markup?
It checks that JSON-LD parses as valid JSON and reports pages with no structured data at all. Invalid JSON-LD is a warning because search engines ignore markup they cannot parse.
Is this a Core Web Vitals test?
No. The performance checks measure server response time and HTML size during the crawl. They point to slow templates and heavy pages; use field data for Core Web Vitals.
Why is a page served over HTTP critical?
Browsers mark HTTP pages as not secure and search engines prefer HTTPS. Any page reachable only over HTTP is critical.
Want the background first? Browse the SiteAuditLint Academy, or see all features.