SEO Technical: Sitemap

Guides sitemap creation, auditing, and optimization for search engine discovery.

When invoking: On first use, if helpful, open with 1–2 sentences on what this skill covers and why it matters, then provide the main output. On subsequent use or when the user asks to skip, go directly to the main output.

Scope (Technical SEO)

Sitemap: Create XML sitemap; submit to Google Search Console
URL discovery: Help search engines find pages; especially important for large sites or poor internal linking

Task

Generate an XML Sitemap that complies with the sitemaps.org protocol from the project's page list, and declare it in robots.txt.

Initial Assessment

Check for project context first: If .claude/project-context.md or .cursor/project-context.md exists, read it for site URL and page structure.

Identify:

Site URL: Base domain (e.g., https://example.com)
URL count: Total indexable pages (single sitemap vs. sitemap index)
Data source: Static config, CMS, file system, or hybrid

1. Protocol Essentials

Item	Spec
Single sitemap limit	50,000 URLs, 50MB (uncompressed)
Sitemap index	When exceeding limit, split and have main index reference sub-sitemaps
Encoding	UTF-8
URL format	Full URL, same host, include `https://`
Required tags	`<loc>`
Optional tags	`<lastmod>`, `<changefreq>`, `<priority>`

2. Field Requirements

Field	Description	Recommendation
url	Full URL	`https://example.com/path`
lastModified	Page last modified time	Use page metadata, ISO 8601; use `YYYY-MM-DD` or omit when no data
changeFrequency	Update frequency	Home `daily`, list pages `weekly`, content pages `monthly`
priority	Relative importance	Home 1.0, aggregate pages 0.9, content pages 0.7–0.8, others 0.5–0.6

lastmod (Critical)

Must be accurate: Reflect actual page modification time, not sitemap generation time. Google requires verifiability; Bing reports ~18% of sitemaps ignored due to lastmod errors.
Format: W3C Datetime (YYYY-MM-DD or YYYY-MM-DDTHH:MM:SS+TZD), e.g. 2025-01-15, 2025-01-15T14:30:00+08:00.
Avoid: Using new Date() for lastmod—causes all URLs to share the same timestamp; search engines may ignore.
Apply when: Content updates, structured data changes, or important link changes.

changefreq / priority

changefreq: Hints only; does not directly determine crawl frequency. Values: always, hourly, daily, weekly, monthly, yearly, never.
priority: 0.0–1.0; does not affect ranking; set higher for important pages; avoid identical values for all.

3. Architecture & Split

Single Sitemap

When URLs >50,000, generate /sitemap.xml directly.

Sitemap Index (Multiple Sub-sitemaps)

When exceeding limit, split by type or language; main index references sub-sitemaps.
Example splits: /sitemap/posts.xml, /sitemap/pages.xml, /sitemap/zh.xml, /sitemap/en.xml.
Main index outputs /sitemap.xml or /sitemap-index.xml, each entry as <sitemap><loc>...</loc></sitemap>.

Multilingual Sites

Split by locale: /sitemap/zh.xml, /sitemap/en.xml.
Or by content type + language: /sitemap/zh-posts.xml, /sitemap/en-posts.xml.

Multi-Language Sitemap (hreflang in Sitemap)

For multilingual sites, add xhtml:link hreflang alternates inside each <url> entry. Recommended for large sites (100+ multilingual pages); centralizes hreflang management.

Rules:

Every language version must link to ALL others, including itself (self-reference).
Include x-default pointing to default locale.
Use xmlns:xhtml="http://www.w3.org/1999/xhtml" namespace.
<loc> typically uses default-locale (clean) URL; x-default points there too.

<?xml version="1.0" encoding="UTF-8"?>
<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9"
        xmlns:xhtml="http://www.w3.org/1999/xhtml">
  <url>
    <loc>https://example.com/page</loc>
    <xhtml:link rel="alternate" hreflang="en" href="https://example.com/page" />
    <xhtml:link rel="alternate" hreflang="zh" href="https://example.com/zh/page" />
    <xhtml:link rel="alternate" hreflang="x-default" href="https://example.com/page" />
  </url>
</urlset>

List all language sitemaps in sitemap index; include in robots.txt.

4. Implementation

Tech Stack	Implementation
Next.js App Router	`app/sitemap.ts` export `MetadataRoute.Sitemap` or `generateSitemaps`
Next.js Pages Router	`pages/sitemap.xml.ts` or `getServerSideProps` return XML
Astro	`src/pages/sitemap-index.xml.ts` or `@astrojs/sitemap`
Vite / Static build	Build script generates `public/sitemap.xml`
Other	Generate static `/sitemap.xml` or return dynamically via API

Route Exclusion

If the project has i18n / middleware redirects, exclude sitemap paths to avoid redirect.
Example (Next.js matcher): '/((?!api|_next|sitemap|sitemap-index|.*\\..*).*)'.

5. Page Scope

Include

Home: /
Locale/region home pages (e.g. /zh, /en)
All indexable content pages, list pages, category pages

Exclude

/api/*, /admin/*, /_next/*
Static assets (images, JS, CSS, etc.). For image discovery, use image sitemap extension—see image-optimization. For video discovery, use video sitemap extension—see video-optimization
Login, admin, drafts, and other pages not intended for indexing

6. Data Source & Maintenance (Single Source of Truth)

Single source of truth: Read URL list from config, CMS, or metadata; avoid hardcoding in sitemap.
Multiple page types: Tools, blog, marketing pages can be merged into one array for unified generation.
New pages: Add only to data source; sitemap updates automatically; avoid maintaining multiple places.

Central Config (Recommended)

Create a config (e.g., site-pages-config.ts) that exports:

Page slugs/paths by section (tools, blog, marketing, etc.)
Optional: modifiedDate per page for accurate lastmod
Function: getAllPageUrls(baseUrl) for sitemap and IndexNow

Why: Sitemap, IndexNow, and feed can all import from the same config—no duplicate URL maintenance. IndexNow should use the same URL list; avoid separate hardcoded lists.

7. robots.txt

Add to robots.txt:

Sitemap: https://example.com/sitemap.xml

With multiple sitemaps, only declare the main index.

8. Output Format

Single Sitemap Example

<?xml version="1.0" encoding="UTF-8"?>
<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">
  <url>
    <loc>https://example.com/</loc>
    <lastmod>2025-01-15</lastmod>
    <changefreq>daily</changefreq>
    <priority>1.0</priority>
  </url>
  <url>
    <loc>https://example.com/page</loc>
    <lastmod>2025-01-10</lastmod>
    <changefreq>weekly</changefreq>
    <priority>0.8</priority>
  </url>
</urlset>

Sitemap Index Example

<?xml version="1.0" encoding="UTF-8"?>
<sitemapindex xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">
  <sitemap>
    <loc>https://example.com/sitemap/pages.xml</loc>
    <lastmod>2025-01-15</lastmod>
  </sitemap>
  <sitemap>
    <loc>https://example.com/sitemap/posts.xml</loc>
    <lastmod>2025-01-14</lastmod>
  </sitemap>
</sitemapindex>

9. Common Issues

Issue	Cause / Fix
Sitemap 404	Build failure, wrong path, incorrect export; check routes and deployment
Missing pages	URLs not in data source, filtered or excluded
lastmod anomaly	Avoid `new Date()`; use `modifiedDate` from page metadata
Google not indexing	Submit sitemap in GSC; check Coverage (google-search-console) and robots
EN/ZH URL mismatch	Use unified data source; share same list when generating by locale

References

Related Skills

website-structure: Plan page structure and URL list; sitemap reflects planned/indexable pages
google-search-console: Sitemap status, indexed URL count, Coverage
robots-txt: Reference sitemap in robots.txt
indexnow: Share same URL list from config
image-optimization: Image sitemap extension for image discovery
video-optimization: Video sitemap extension for video discovery

xml-sitemap