SEO — Sitemap

Overview

A Sitemap is an XML file (or RSS/Atom/text alternative) that lists URLs on your site so search engines can discover and crawl them more efficiently. It supplements link-based discovery; it does not guarantee indexing.

Principles: UTF-8 encoding; absolute URLs with protocol; one host per sitemap; accurate lastmod; stay under size limits; place at site root when possible.

Reference: sitemaps.org protocol · FAQ

When to use a sitemap

Pair with robots.txt (Sitemap: https://example.com/sitemap.xml) and Search Console submission.

XML format (protocol 0.9)

Required structure:

<?xml version="1.0" encoding="UTF-8"?>
<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">
  <url>
    <loc>https://www.example.com/</loc>
    <lastmod>2025-06-13</lastmod>
    <changefreq>monthly</changefreq>
    <priority>0.8</priority>
  </url>
</urlset>

Entity escaping in XML: & → &, < → <, > → >, " → ", ' → '.

Limits (FAQ)

• Max 50,000 URLs per sitemap file.
• Max 50 MB uncompressed (52,428,800 bytes).
• Use gzip compression when serving (file must still be ≤50 MB uncompressed).
• Exceed limits → split into multiple sitemaps + sitemap index.

Sitemap index

<?xml version="1.0" encoding="UTF-8"?>
<sitemapindex xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">
  <sitemap>
    <loc>https://www.example.com/sitemap-posts.xml</loc>
    <lastmod>2025-06-13T12:00:00+00:00</lastmod>
  </sitemap>
  <sitemap>
    <loc>https://www.example.com/sitemap-pages.xml</loc>
    <lastmod>2025-06-01</lastmod>
  </sitemap>
</sitemapindex>

Index: max 50,000 sitemaps, max 50 MB. Index lastmod = when that sitemap file changed (enables incremental crawl).

File location rules

• Recommended: https://example.com/sitemap.xml (root).
• All <loc> URLs must share the same protocol and host as the sitemap (e.g. no http URLs in an https sitemap).
• Subpath sitemap (/catalog/sitemap.xml) may only list URLs under /catalog/.
• List one canonical version of each URL (not both http and https).
• No session IDs in URLs.
• Include frameset and frame content URLs if site uses frames (legacy).

Next.js (App Router)

Use app/sitemap.ts exporting default async function returning MetadataRoute.Sitemap:

import type { MetadataRoute } from 'next'

const SITE = 'https://example.com'

export default async function sitemap(): Promise<MetadataRoute.Sitemap> {
  const staticPages: MetadataRoute.Sitemap = [
    { url: `${SITE}/`, lastModified: new Date(), priority: 1 },
    { url: `${SITE}/about`, lastModified: new Date(), priority: 0.8 },
  ]

  const posts = await fetchPostSlugs()
  const postPages = posts.map((slug) => ({
    url: `${SITE}/blog/${slug}`,
    lastModified: new Date(),
    priority: 0.7,
  }))

  return [...staticPages, ...postPages]
}

• Next.js serves at /sitemap.xml automatically.
• Use real lastModified from CMS when available.
• For multiple sitemaps, use generateSitemaps (Next.js 13.3+) or route handlers.

robots.txt

User-agent: *
Allow: /

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

After publishing

1. Validate XML against sitemap.xsd.
2. Submit in Google Search Console / Bing Webmaster Tools.
3. Add Sitemap: line to robots.txt.
4. Monitor crawl stats; update lastmod when content actually changes.

vs JSON-LD and llms.txt

Use all three (sitemap, json-ld, llms-txt) for a complete discoverability stack.

Common mistakes

• Wrong lastmod — sitemap generation date instead of page update date.
• Relative URLs — must include https://.
• Mixed hosts — subdomain URLs in www sitemap.
• Session IDs in <loc>.
• Duplicate http/https entries for same page.
• Priority 1.0 everywhere — dilutes relative signaling.
• Unescaped & in query strings — breaks XML.
• Oversized file — split before hitting 50k / 50MB.

Related skills

• json-ld — structured data on pages listed in the sitemap.
• llms-txt — llms.txt for AI assistants (curated, not a sitemap replacement).

Additional resources

• [reference.md](reference.md) — Protocol, FAQ, schemas, Search Console, Next.js.
• Protocol: https://www.sitemaps.org/protocol.html
• FAQ: https://www.sitemaps.org/faq.php