As of 2025-2026, AI companies actively crawl the web to train models and power AI search. Managing these crawlers via robots.txt is a critical technical SEO consideration.

Known AI crawlers:

Crawler	Company	robots.txt token	Purpose
GPTBot	OpenAI	`GPTBot`	Model training
ChatGPT-User	OpenAI	`ChatGPT-User`	Real-time browsing
ClaudeBot	Anthropic	`ClaudeBot`	Model training
PerplexityBot	Perplexity	`PerplexityBot`	Search index + training
Bytespider	ByteDance	`Bytespider`	Model training
Google-Extended	Google	`Google-Extended`	Gemini training (NOT search)
CCBot	Common Crawl	`CCBot`	Open dataset

Key distinctions:

Blocking Google-Extended prevents Gemini training use but does NOT affect Google Search indexing or AI Overviews (those use Googlebot)
Blocking GPTBot prevents OpenAI training but does NOT prevent ChatGPT from citing your content via browsing (ChatGPT-User)
~3-5% of websites now use AI-specific robots.txt rules

Example, selective AI crawler blocking:

# Allow search indexing, block AI training crawlers
User-agent: GPTBot
Disallow: /

User-agent: Google-Extended
Disallow: /

User-agent: Bytespider
Disallow: /

# Allow all other crawlers (including Googlebot for search)
User-agent: *
Allow: /

Recommendation: Consider your AI visibility strategy before blocking. Being cited by AI systems drives brand awareness and referral traffic. Cross-reference the seo-geo skill for full AI visibility optimization.

2. Indexability

Canonical tags: self-referencing, no conflicts with noindex
Duplicate content: near-duplicates, parameter URLs, www vs non-www
Thin content: pages below minimum word counts per type
Pagination: rel=next/prev or load-more pattern
Hreflang: correct for multi-language/multi-region sites
Index bloat: unnecessary pages consuming crawl budget

3. Security

HTTPS: enforced, valid SSL certificate, no mixed content
Security headers:
- Content-Security-Policy (CSP)
- Strict-Transport-Security (HSTS)
- X-Frame-Options
- X-Content-Type-Options
- Referrer-Policy
HSTS preload: check preload list inclusion for high-security sites

4. URL Structure

Clean URLs: descriptive, hyphenated, no query parameters for content
Hierarchy: logical folder structure reflecting site architecture
Redirects: no chains (max 1 hop), 301 for permanent moves
URL length: flag >100 characters
Trailing slashes: consistent usage

5. Mobile Optimization

Responsive design: viewport meta tag, responsive CSS
Touch targets: minimum 48x48px with 8px spacing
Font size: minimum 16px base
No horizontal scroll
Mobile-first indexing: Google indexes mobile version. Mobile-first indexing is 100% complete as of July 5, 2024. Google now crawls and indexes ALL websites exclusively with the mobile Googlebot user-agent.

6. Core Web Vitals

LCP (Largest Contentful Paint): target <2.5s
INP (Interaction to Next Paint): target <200ms
- INP replaced FID on March 12, 2024. FID was fully removed from all Chrome tools (CrUX API, PageSpeed Insights, Lighthouse) on September 9, 2024. Do NOT reference FID anywhere.
CLS (Cumulative Layout Shift): target <0.1
Evaluation uses 75th percentile of real user data
Use PageSpeed Insights API or CrUX data if MCP available

7. Structured Data

Detection: JSON-LD (preferred), Microdata, RDFa
Validation against Google's supported types
See seo-schema skill for full analysis

8. JavaScript Rendering

Check if content visible in initial HTML vs requires JS
Identify client-side rendered (CSR) vs server-side rendered (SSR)
Flag SPA frameworks (React, Vue, Angular) that may cause indexing issues
Verify dynamic rendering setup if applicable

JavaScript SEO: Canonical & Indexing Guidance (December 2025)

Google updated its JavaScript SEO documentation in December 2025 with critical clarifications:

Canonical conflicts: If a canonical tag in raw HTML differs from one injected by JavaScript, Google may use EITHER one. Ensure canonical tags are identical between server-rendered HTML and JS-rendered output.
noindex with JavaScript: If raw HTML contains <meta name="robots" content="noindex"> but JavaScript removes it, Google MAY still honor the noindex from raw HTML. Serve correct robots directives in the initial HTML response.
Non-200 status codes: Google does NOT render JavaScript on pages returning non-200 HTTP status codes. Any content or meta tags injected via JS on error pages will be invisible to Googlebot.
Structured data in JavaScript: Product, Article, and other structured data injected via JS may face delayed processing. For time-sensitive structured data (especially e-commerce Product markup), include it in the initial server-rendered HTML.

Best practice: Serve critical SEO elements (canonical, meta robots, structured data, title, meta description) in the initial server-rendered HTML rather than relying on JavaScript injection.

9. IndexNow Protocol

Check if site supports IndexNow for Bing, Yandex, Naver
Supported by search engines other than Google
Recommend implementation for faster indexing on non-Google engines

Output

Technical Score: XX/100

Category Breakdown

Category	Status	Score
Crawlability	pass/warn/fail	XX/100
Indexability	pass/warn/fail	XX/100
Security	pass/warn/fail	XX/100
URL Structure	pass/warn/fail	XX/100
Mobile	pass/warn/fail	XX/100
Core Web Vitals	pass/warn/fail	XX/100
Structured Data	pass/warn/fail	XX/100
JS Rendering	pass/warn/fail	XX/100
IndexNow	pass/warn/fail	XX/100

Critical Issues (fix immediately)

High Priority (fix within 1 week)

Medium Priority (fix within 1 month)

Low Priority (backlog)

DataForSEO Integration (Optional)

If DataForSEO MCP tools are available, use on_page_instant_pages for real page analysis (status codes, page timing, broken links, on-page checks), on_page_lighthouse for Lighthouse audits (performance, accessibility, SEO scores), and domain_analytics_technologies_domain_technologies for technology stack detection.

Error Handling

Scenario	Action
URL unreachable	Report connection error with status code. Suggest verifying URL, checking DNS resolution, and confirming the site is publicly accessible.
robots.txt not found	Note that no robots.txt was detected at the root domain. Recommend creating one with appropriate directives. Continue audit on remaining categories.
HTTPS not configured	Flag as a critical issue. Report whether HTTP is served without redirect, mixed content exists, or SSL certificate is missing/expired.
Core Web Vitals data unavailable	Note that CrUX data is not available (common for low-traffic sites). Suggest using Lighthouse lab data as a proxy and recommend increasing traffic before re-testing.

Limitations

Use this skill only when the task clearly matches the scope described above.
Do not treat the output as a substitute for environment-specific validation, testing, or expert review.
Stop and ask for clarification if required inputs, permissions, safety boundaries, or success criteria are missing.

seo-technical

Technical SEO Audit

When to Use

Categories

1. Crawlability

AI Crawler Management