SEO Analysis

The SEO Analysis extension is a comprehensive, offline-first SEO toolkit with 30+ tools covering every aspect of technical, on-page, and content SEO. No external API keys or services are required — everything runs locally.

Tool Categories

Crawling & Discovery

Tool	What It Does
`seo_crawl`	Crawl an entire site, discover all subpages, detect broken links
`seo_crawl_report`	Generate detailed crawl analysis with link graph, orphans, duplicates
`seo_sitemap_analyze`	Parse and analyze XML sitemaps
`seo_sitemap_generate`	Generate valid XML sitemaps from URL lists

On-Page Analysis

Tool	What It Does
`seo_fetch`	Fetch page HTML with redirect-chain tracking
`seo_render`	Render SPA pages with Playwright (JavaScript-aware)
`seo_parse_page`	Extract all on-page elements: title, meta, headings, images, links, schema, OG tags
`seo_content_optimize`	Check title/meta lengths, heading hierarchy, content length

Technical SEO

Tool	What It Does
`seo_technical_audit`	Crawlability, indexability, HTTPS, security headers, mobile, AI crawlers
`seo_performance`	Estimate Core Web Vitals: LCP, CLS, TBT, FCP, TTFB
`seo_page_weight`	Analyze page weight by resource type
`seo_render_blocking`	Detect render-blocking CSS/JS with fixes
`seo_font_audit`	Audit web fonts: font-display, WOFF2, Google Fonts vs self-hosted

Content Quality

Tool	What It Does
`seo_content_quality`	QRG-aligned heuristics: filler, AI patterns, information density, repetition
`seo_keywords`	TF-IDF keyword extraction with n-grams and search intent
`seo_keyword_density`	Check density of target keywords
`seo_readability`	Flesch-Kincaid, SMOG, ARI, Coleman-Liau scores
`seo_competitor_gap`	Compare your page against a competitor

Structured Data

Tool	What It Does
`seo_schema_audit`	Detect and validate Schema.org (JSON-LD, Microdata, RDFa)
`seo_schema_generate`	Generate JSON-LD for 12+ schema types

Images & Preloading

Tool	What It Does
`seo_image_audit`	Audit images: alt text, dimensions, lazy loading, modern formats
`seo_preload_audit`	Speculation Rules API, preload hints, bfcache, LCP fetchpriority

Advanced

Tool	What It Does
`seo_agent_ux_audit`	AI-agent friendliness: a11y tree, semantic HTML, interactive widgets
`seo_parasite_risk`	Scan URLs for parasite-SEO risk by subfolder
`seo_drift_baseline`	Capture SEO baseline snapshot for drift monitoring
`seo_drift_compare`	Compare current page against a baseline
`seo_drift_history`	List baseline snapshots for a URL
`seo_audit`	Full audit: technical + content + schema + images + preload + agent UX
`seo_audit_batch`	Audit multiple URLs and compare scores
`seo_report`	Generate formatted reports in Markdown, JSON, or HTML

Full Audit in One Call

The seo_audit tool runs all sub-audits in one call, returning an overall score and prioritized issues:

seo_audit {
  url: "https://mysite.com",
  include: ["technical", "content", "schema", "images", "preload", "agentUx"]
}

You can also run individual sub-audits for focused analysis:

seo_audit {
  url: "https://mysite.com",
  include: ["technical"]
}

Crawl → Audit Workflow

The recommended workflow for a full site audit:

Crawl — seo_crawl { url, maxPages: 100 } discovers all pages
Analyze — seo_crawl_report shows broken links, duplicates, orphans
Audit — seo_audit_batch runs audits on key discovered pages
Report — seo_report generates a formatted summary

Drift Monitoring

The drift tools let you capture baselines and detect unwanted SEO changes:

// Capture a baseline
seo_drift_baseline { url: "https://mysite.com/pricing" }

// ... time passes, someone edits the page ...

// Detect what changed
seo_drift_compare { url: "https://mysite.com/pricing" }
// → Reports changes in title, meta, H1, schema, robots, canonical, etc.

Baselines are stored in a local SQLite database (~/.spectral/seo/drift.db).

Offline-First Design

Every tool runs entirely locally:

No API keys — no Google, Ahrefs, or SEMrush keys needed
No rate limits — analyze as many pages as you want
Privacy-safe — page content never leaves your machine
Batteries included — Playwright for rendering, SQLite for drift DB

When to Use

Pre-launch audit — catch SEO issues before going live
Competitor analysis — compare your pages against competitors
Content optimization — improve keyword density and readability
Schema validation — ensure structured data is correct
Migration monitoring — use drift tools to detect unintended SEO changes
Site health checks — crawl for broken links and duplicate content