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JSON-LD vs Microdata

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4.1 The Fundamental Difference

Microdata embeds structured data directly in HTML tag attributes: 
<div itemscope itemtype="https://schema.org/Product">
  <h1 itemprop="name">Classic Canvas Sneakers</h1>
  <span itemprop="description">Comfortable, breathable canvas shoes</span>
  <div itemprop="offers" itemscope itemtype="https://schema.org/Offer">
    <span itemprop="price" content="49.99">$49.99</span>
    <meta itemprop="priceCurrency" content="USD">
    <link itemprop="availability" href="https://schema.org/InStock">
  </div>
</div>
JSON-LD places structured data in a standalone script tag: 
<script type="application/ld+json">
{
  "@context": "https://schema.org",
  "@type": "Product",
  "name": "Classic Canvas Sneakers",
  "description": "Comfortable, breathable canvas shoes",
  "offers": {
    "@type": "Offer",
    "price": "49.99",
    "priceCurrency": "USD",
    "availability": "https://schema.org/InStock"
  }
}
</script>

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4.2 Detailed Comparison

DimensionJSON-LDMicrodata
LocationStandalone script tag, typically in headEmbedded in HTML tag attributes
HTML couplingFully decoupledTightly coupled
Maintenance costLow — data changes do not affect page structureHigh — markup changes may break page layout
Dynamic generationEasy — backend outputs JSONDifficult — requires HTML template modification
ReadabilityHigh — standard JSON formatLow — scattered across HTML tags
Google recommendationYes (officially preferred)Supported but not preferred
AI agent parsingMore efficient (standard JSON parsing)Requires DOM tree traversal
Multi-entity linkingSimple (JSON nesting)Complex (requires itemref for cross-element references)
SSR/SSG compatibilityFully compatibleFully compatible
CSR (SPA) compatibilityMust ensure markup is visible to crawlersSame

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4.3 When Microdata May Be a Better Fit

Although JSON-LD is the general recommendation, there are a few scenarios where Microdata may be more appropriate:
  1. Your CMS templates already output Microdata — If your WordPress theme already produces correct Microdata with complete fields, there is no need to refactor just to change formats
  2. Markup must strictly match visible content — Microdata inherently guarantees consistency between markup and on-page content (because they are the same HTML)
  3. Minimal pages — Simple scenarios with a single Product or single Article

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4.4 Migrating from Microdata to JSON-LD

If you decide to migrate, follow these steps: Step 1: Extract existing Microdata Locate all itemscope and itemprop attributes on the page and document the data structure. Step 2: Build the equivalent JSON-LD Map each Microdata itemprop to its JSON-LD key:
MicrodataJSON-LD
Text content of itemprop="name""name": "text content"
itemprop="price" content="49.99""price": "49.99"
itemtype="https://schema.org/Offer""@type": "Offer"
Step 3: Add JSON-LD while keeping Microdata Run both formats simultaneously for 1-2 weeks. Use validation tools to confirm the JSON-LD output is correct before removing Microdata. Step 4: Remove Microdata attributes Delete itemscope, itemtype, and itemprop attributes from HTML tags. Be careful not to remove the tags themselves or their CSS class names.
Migration does not need to happen all at once. Start with the most important pages (product detail pages, homepage) and gradually expand to the entire site.

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4.5 Validating the Migration

Post-migration validation is essential:
  1. Use Google Rich Results Test to validate JSON-LD output
  2. Compare data fields before and after migration to confirm nothing was lost
  3. Monitor the Structured Data report in Google Search Console for errors
Next chapter: robots.txt Optimization — Precise access control configuration for AI crawlers