Schema Markup & JSON-LD Validator

Validate and inspect Schema.org JSON-LD structured data via live URL scraping or direct code input to optimize for Google Rich Snippets and AI Search citations.

Technical Architecture: Reverse-Engineering JSON-LD Validation​

Schema.org structured data enables search crawlers and LLM knowledge graphs to parse semantic entities (organizations, software applications, articles, ratings) directly from machine-readable JSON-LD tags embedded within the HTML document.

The validator operates in dual mode: client-side JSON parsing for direct code snippets, and serverless proxy extraction (/api/fetchSchema) for live public URLs.

1. Serverless JSON-LD Extraction & Graph Parsing​

When validating a live URL, /api/fetchSchema retrieves the remote HTML payload and queries all script tags targeting the MIME type application/ld+json:

// api/fetchSchema.js (extraction pipeline)
const cheerio = require('cheerio');

module.exports = async (req, res) => {
  const { url } = req.query;
  const targetUrl = new URL(url);

  const response = await fetch(targetUrl.toString(), {
    headers: {
      'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) SchemaValidator/1.0',
      'Accept': 'text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8'
    },
    signal: AbortSignal.timeout(10000)
  });

  const html = await response.text();
  const $ = cheerio.load(html);
  const schemas = [];

  $('script[type="application/ld+json"]').each((_, el) => {
    try {
      const rawContent = $(el).html();
      if (rawContent) {
        const parsed = JSON.parse(rawContent.trim());
        // Schema.org can be a single object, an array, or an @graph container
        if (Array.isArray(parsed)) {
          schemas.push(...parsed);
        } else if (parsed['@graph'] && Array.isArray(parsed['@graph'])) {
          schemas.push(...parsed['@graph']);
        } else {
          schemas.push(parsed);
        }
      }
    } catch (parseError) {
      schemas.push({
        error: 'JSON Syntax Error',
        details: parseError.message,
        raw: $(el).html()
      });
    }
  });

  res.status(200).json({ schemas, totalFound: schemas.length });
};

2. Common RFC 8259 Syntax Pitfalls​

Because search engines reject malformed JSON without evaluating entity semantics, the tool checks for standard syntax violations:

3. Core Schema.org Entities Reference​

4. Client-Side Security & Zero-Server Data Guarantee​

• Direct Snippet Privacy: When pasting code into the validator, evaluation is performed 100% locally in your browser's V8 engine. No pasted data is sent over the network.
• Ephemeral Proxy Requests: Live URL fetches do not log visited endpoints or store parsed schemas in databases.
• SSRF Mitigation: The fetch proxy blocks requests to RFC 1918 private subnets and localhost loops.

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