AI search engines and crawlers increasingly reward content that carries verifiable signals of who reviewed it. Schema.org's reviewedBy is the property that says "a named reviewer checked this page for accuracy." This library emits correct, validatable JSON-LD for that — free, zero-dependency, and MIT-licensed.

What it does — and does not do. It builds valid WebPage → reviewedBy → Person + hasCredential markup and warns on common E-E-A-T mistakes. It does not verify that a credential is real. That binding — a vetted expert and a board-checked credential — is the CertREV service.

Why this shape

Verified against schema.org (v30):

• reviewedBy is a property of WebPage, with a range of Person or Organization.
• lastReviewed (also on WebPage) carries the review date.
• The reviewer's expertise is modeled as Person → hasCredential → EducationalOccupationalCredential, with credentialCategory and recognizedBy (the issuing board / authority).

So this library produces a WebPage with reviewedBy + lastReviewed, the content as mainEntity (an Article with its own author and publisher), and the reviewer's credential modeled properly — the structure Google and LLM crawlers actually parse.

Install

npm install github:CertREV/reviewedby-schema
# (npm registry release coming soon)

Zero dependencies, ES modules, Node >= 18.

Quick start

import { generate, toScriptTag, validate } from 'reviewedby-schema'

const input = {
  page: { url: 'https://example.com/blog/glycolic-acid-guide' },
  article: {
    headline: 'The Complete Guide to Glycolic Acid for Skin Renewal',
    datePublished: '2026-05-01',
    author: { name: 'Sarah Mitchell', jobTitle: 'Beauty Editor' },
  },
  reviewer: {
    name: 'Dr. Elena Vasquez',
    jobTitle: 'Board-Certified Dermatologist',
    url: 'https://example.com/experts/elena-vasquez',
    credential: {
      name: 'Board Certified in Dermatology',
      category: 'board certification',
      recognizedBy: { name: 'American Board of Dermatology', url: 'https://www.abderm.org' },
    },
  },
  organization: { name: 'CertREV', url: 'https://certrev.com', logo: 'https://certrev.com/logo.png' },
  dateReviewed: '2026-06-02',
}

const check = validate(input)        // { valid, errors[], warnings[] }
const html = toScriptTag(generate(input))  // ready-to-paste <script> block

API

generate(input) → object

Returns the JSON-LD WebPage object. Throws if reviewer.name is missing. Undefined/empty fields are pruned, so the output never contains nulls.

toScriptTag(jsonld) → string

Wraps a JSON-LD object in a ready-to-paste <script type="application/ld+json"> block.

validate(input) → { valid, errors, warnings }

Checks required fields (a reviewer name and a page/article URL) and warns on common E-E-A-T gaps: a missing credential, no recognizedBy authority, a non-standard credentialCategory, a missing dateReviewed, a missing publisher, no author, or non-ISO dates.

CREDENTIAL_CATEGORIES

The frozen list of recommended credentialCategory values: license, certification, degree, board certification, professional designation.

Example output

{
  "@context": "https://schema.org",
  "@type": "WebPage",
  "url": "https://example.com/blog/glycolic-acid-guide",
  "reviewedBy": {
    "@type": "Person",
    "name": "Dr. Elena Vasquez",
    "hasCredential": {
      "@type": "EducationalOccupationalCredential",
      "name": "Board Certified in Dermatology",
      "credentialCategory": "board certification",
      "recognizedBy": { "@type": "Organization", "name": "American Board of Dermatology" }
    }
  },
  "lastReviewed": "2026-06-02",
  "mainEntity": { "@type": "Article", "headline": "...", "author": { "@type": "Person", "name": "Sarah Mitchell" } }
}

See examples/ for a full runnable example.

What good provenance includes

A named reviewer, their credential, the issuing authority, the review date, and a stable URL for the reviewer. validate() nudges you toward all five.

How CertREV uses this

This is the open schema layer. CertREV adds the parts that make the markup true: vetted experts, board-checked credentials, SHA-256 content hashing, a public certificate page, and embeddable trust badges. Learn more at certrev.com.

Contributing

Issues and PRs welcome. Run the tests with npm test (node --test, no build step).

License

MIT © CERTREV LLC