Seo

On-Page SEO — Blog & Content Reference

Concrete limits, rules, and checklists for on-page SEO. All numbers reflect Google's current SERP rendering (2025-2026).

Title Tag

Quick check: If your title exceeds 55 characters, verify pixel width with a SERP preview tool.

Meta Description

Rule: Front-load the value proposition into the first 120 characters — everything after may be truncated on mobile.

Heading Structure (H1-H6)

URL / Slug

Image SEO

Internal Linking

Content Structure & Length

Open Graph & Social Meta Tags

OG uses property attribute, Twitter uses name attribute. Set both and keep in sync.

Canonical URL

XML Sitemap

Content Freshness

Schema.org / Structured Data (BlogPosting)

Use BlogPosting type with JSON-LD format for blog content:

jsonCopy code
{
    "@context": "https://schema.org",
    "@type": "BlogPosting",
    "headline": "Titel des Beitrags",
    "image": [
        "https://example.de/bild-16x9.webp",
        "https://example.de/bild-4x3.webp",
        "https://example.de/bild-1x1.webp"
    ],
    "datePublished": "2026-06-04T10:00:00+02:00",
    "dateModified": "2026-06-04T12:00:00+02:00",
    "author": {
        "@type": "Person",
        "name": "Autorenname",
        "url": "https://example.de/ueber-uns/"
    },
    "publisher": {
        "@type": "Organization",
        "name": "Firmenname",
        "url": "https://example.de/"
    }
}

Additional Schema Types

BreadcrumbList

Use on every page for navigation path display in SERPs:

jsonCopy code
{
    "@context": "https://schema.org",
    "@type": "BreadcrumbList",
    "itemListElement": [
        { "@type": "ListItem", "position": 1, "name": "Blog", "item": "https://example.de/blog/" },
        { "@type": "ListItem", "position": 2, "name": "SEO Leitfaden", "item": "https://example.de/blog/seo-leitfaden/" }
    ]
}

FAQPage

Use when the post contains a dedicated FAQ section with question-answer pairs:

jsonCopy code
{
    "@context": "https://schema.org",
    "@type": "FAQPage",
    "mainEntity": [
        {
            "@type": "Question",
            "name": "Wie lang sollte ein Title-Tag sein?",
            "acceptedAnswer": { "@type": "Answer", "text": "50-60 Zeichen bzw. max 580 Pixel Breite." }
        }
    ]
}

Combine multiple schema types on one page by wrapping them in a @graph array.

E-E-A-T Signals

Core Web Vitals

Mobile-First

Robots Meta

German SEO Specifics

Umlauts in URLs

Google treats "ue" the same as "ü" for keyword matching. Never just drop the dots (ü→u is wrong).

Flesch-Index (German Adaptation — Amstad 1978)

Formula: 180 - SL - (58.5 × WL) (SL = sentence length in words, WL = avg syllables per word)

German words are inherently longer (compound nouns), so scores are naturally lower than English.

Hreflang (DACH)

Requirements: Bidirectional linking (all versions link to all others + self); absolute URLs; all return HTTP 200.

Legal Requirements (Trust Signals)

German sites require Impressum and Datenschutzerklärung — both affect trust signals and are legally mandatory.

Domain & Market

• .de ccTLD provides strong geo-targeting signal for Germany
• Google.de has ~90%+ market share in Germany
• "Sie" vs "du" — consistency matters; trend 2025-2026 is "du" for B2C

Verlinkung mit Copywriter-Skills

Beim Schreiben von Texten gelten SEO-Limits UND Tonalitätsregeln gemeinsam:

Kein Widerspruch: Die Copywriter-Skills bestimmen Stimme, Rhythmus und Struktur. Dieser Skill bestimmt die technischen Limits (Zeichenlängen, Pixel, Heading-Hierarchie, Schema). Beide ergänzen sich.

Wichtig: Die H1 auf der Seite darf emotionaler und länger sein als der Title-Tag. Der Title-Tag ist für die SERPs optimiert (50-60 Zeichen), die H1 für den Leser auf der Seite.

Blog Post SEO Checklist

Use this checklist when writing or reviewing a blog post:

Content & Keywords:

• Focus keyword appears in title, H1, meta description, URL slug, and first paragraph
• Focus keyword is unique to this post (no keyword cannibalization)
• Keyword density 1-2%, naturally distributed
• Content length appropriate for type (see table above), minimum 300 words
• Featured snippet paragraph (40-60 words) after key heading

Structure & Readability:

• One H1 per page, heading hierarchy sequential (H1→H2→H3)
• Max 300 words between subheadings
• Flesch-Index 50-60 for German texts
• Max 10% passive voice
• Mind. 30% of sentences with transition words
• Sentence length varies visibly

Meta & SERP:

• Title: 50-60 characters, primary keyword near beginning, ≤580 px
• Meta description: 120-158 characters, focus keyword included, CTA, value in first 120 chars
• URL/slug: 3-5 words, lowercase, hyphens, keyword first, umlauts replaced
• Canonical URL: Self-referencing, absolute HTTPS

Links:

• Internal links: 2-5 per 1,000 words, descriptive anchor text
• Outbound links: 1-2 authoritative external sources
• No orphan pages — at least one internal link points to this post
• Table of contents for posts >1,000 words

Images:

• Alt text (80-140 chars), descriptive filenames, keyword-relevant
• WebP/AVIF format, width/height attributes set
• Hero image: loading="eager" + fetchpriority="high"; rest: loading="lazy"

Technical:

• Schema.org: BlogPosting JSON-LD with headline, image, dates, author, publisher
• Schema.org: BreadcrumbList JSON-LD for navigation path
• Schema.org: FAQPage JSON-LD if post contains FAQ section
• Open Graph: og:title, og:description, og:image (1200×630), og:type="article"
• XML Sitemap: Post included with correct <lastmod>
• Content freshness: "Zuletzt aktualisiert" date visible + dateModified in Schema

E-E-A-T:

• Author byline with bio link
• Specific claims backed by data or sources
• "Zuletzt aktualisiert" date visible on page
• Impressum and Datenschutzerklärung accessible

Mobile:

• Content parity with desktop
• Touch targets ≥48 px, viewport meta set
• Page load <3 seconds on mobile

Sources

This skill was compiled from the following references (2025-2026):

Google Official:

• Google Search Central — Article Structured Data
• Google Search Central — URL Structure
• Google Search Central — Mobile-First Indexing
• Google Search Central — Helpful Content
• Google Search Central — Hreflang
• Google Search Central — Google Images Best Practices

Title & Meta:

• Zyppy — Meta Title Tag Length
• Search Engine Land — Title Tag Length
• The Ocean Marketing — Title Tag Length Best Practices
• Scalenut — Meta Title Length Best Practices 2026
• MRS Digital — Meta Length Checker

Content & Readability:

• SEO.co — Content Length
• Lovable.dev — Blog Post Length Guide
• Yoast — Flesch Reading Ease Score
• Yoast — How to Use Headings
• Conductor — Headings for SEO

URL & Slug:

• Slug Genius — URL Slug Best Practices
• Shopify — SEO-Friendly URLs

Structured Data:

• Search Engine Zine — Article vs Blog Schema
• Open Graph Protocol
• Ahrefs — Open Graph Meta Tags

Image SEO:

• AltText.ai — Image Alt Text SEO Best Practices
• Digital Applied — Image SEO Guide 2026

Internal Linking:

• Upward Engine — Internal Linking Best Practices
• Traffic Think Tank — Internal Linking

Core Web Vitals:

• CoreWebVitals.io
• Mewa Studio — SEO Core Web Vitals 2026

E-E-A-T:

• BKND Development — EEAT SEO Strategy 2026
• Search Engine Land — Google E-E-A-T for SEO

German SEO:

• WebCertain — Umlauts in German SEO
• Nikolai Sroka — Flesch Index Lesbarkeit
• Seokratie — SEO-Faktor Lesbarkeit
• Outreach Monks — Hreflang SEO

Existing Claude Code SEO Skills (inspiration):

• AgriciDaniel/claude-seo
• aaron-he-zhu/seo-geo-claude-skills
• aevans-eng/seo-skill