Schema markup is one of the few places in SEO where you can do everything else right and still get nothing back if the implementation has a syntax error. A single missing required property, a mismatched data type, or a JSON formatting mistake is enough to disqualify a page from the rich results its schema was supposed to earn. Worse, invalid schema that Google detects actively may generate structured data errors in Search Console that indicate a quality problem on the page.

Validation closes this gap. The TopWebPositions Schema & Structured Data Tester inspects any URL for JSON-LD, Microdata, and RDFa schema, identifies the types detected, and checks the required and recommended properties against Google's rich result specifications. This guide explains how to use it, what to look for in the results, and how to fix the most common classes of schema errors.

Why Schema Validation Matters

Schema markup communicates structured information about your content directly to search engines in a format they can parse without interpretation. When it's implemented correctly, it opens eligibility for rich results: review stars, recipe cards, event listings, product price displays, breadcrumbs, and more. Rich results consistently earn higher click-through rates than standard blue links for the same position, because they're more visually prominent and communicate more information in the SERP.

When schema is implemented incorrectly, one of three things happens. The markup may be syntactically broken, in which case Google can't parse it and treats it as if it doesn't exist. The required properties for a specific rich result type may be missing, making the page ineligible for that result type even though the schema is technically parseable. Or the schema may conflict with the visible content on the page, which Google's policies explicitly prohibit and which can result in manual actions for sites with widespread mismatches.

Validation catches all three problems before they affect your search appearance.

How to Use the Schema & Structured Data Tester

Navigate to the Schema & Structured Data Tester and enter the URL you want to check. The tool fetches the page, extracts all structured data found in the HTML (JSON-LD, Microdata, and RDFa), and returns a report showing every schema type detected along with property-level detail.

Reading the Schema Detection Results

The tool identifies which schema types are present on the page. For each type, it shows the properties found and highlights any properties that are required for the corresponding Google rich result type. A Product page, for instance, needs the product's name plus at least one of offers, review, or aggregateRating. Missing these disqualifies the page from product rich results even if the rest of the schema is correct.

For each schema type, the output distinguishes between required properties (missing these prevents the rich result), recommended properties (missing these reduces richness but doesn't prevent the result), and optional properties (present as enhancements). Work through required properties first, then recommended ones once the required set is complete.

Common Schema Errors and How to Fix Them

JSON syntax errors. Invalid JSON, such as unclosed brackets, missing commas between properties, or mismatched quotation marks, prevents the entire block from being parsed. The tool surfaces these as parse errors rather than property-level warnings. Fix them by validating the raw JSON in a JSON validator like JSONLint before re-running the schema check. If you're generating schema manually, the Schema Markup Generator produces syntactically valid JSON-LD from plain inputs, eliminating this class of error entirely.

Missing required properties. Many rich result types have specific required fields. Product schema requires name and either offers or review or aggregateRating. Event schema requires fields such as name, startDate, and location. Some types have no required fields at all: Google's documentation for Article markup lists only recommended properties, such as headline, image, and datePublished. When the tester flags a required property as missing, add it to the JSON-LD block in the page's <head> and re-validate.

Incorrect data types. Schema properties have expected data types. A datePublished field should contain an ISO 8601 date string (2026-09-10 or 2026-09-10T09:00:00+00:00), not a plain English date. A ratingValue should be a number, not a string like "4.5 stars." Type mismatches may parse without error but fail Google's validation checks. The tester flags these when detectable.

Schema-to-content mismatch. Google's structured data policies require that schema markup reflects content actually visible on the page. A ratingValue of 4.8 in schema on a page that displays no visible reviews, or an aggregateRating with a reviewCount that doesn't match the number of reviews displayed, is a policy violation. The tool flags schema properties that appear potentially inconsistent with visible page content. Fix these by either updating the schema to match what's actually shown or updating the page to display the information the schema describes.

Deprecated properties. Schema.org evolves, and properties that were valid in previous versions are occasionally deprecated or replaced. Using deprecated properties doesn't break parsing, but it may reduce compatibility with current rich result specifications. The tester flags deprecated property usage and where possible suggests the current equivalent.

Schema Validation as Part of a Pre-Publish Checklist

The most effective way to prevent schema errors is to validate before publishing rather than after. A page that's been live for three months with broken schema has missed three months of rich result eligibility. Adding a validation step to your publishing workflow takes less than a minute and catches errors at the point where they're easiest to fix.

For pages already live, run a systematic validation pass across any page where you've implemented schema: product pages, blog posts with Article schema, local business location pages, and event pages. Search Console's Enhancements reports flag pages with structured data errors and warnings, making it easy to identify which live pages need attention without checking every URL manually.

Generating Schema From Scratch

If you're implementing schema for the first time, or extending schema types you haven't used before, the Schema Markup Generator builds valid JSON-LD for the most common types: Article, Product, LocalBusiness, Organization, Event, BreadcrumbList, and FAQPage. Enter your page details into the plain-language fields and the generator outputs a correctly structured JSON-LD block ready to paste into your page's <head>.

After generating and implementing, run the page through the tester to confirm it validates correctly in context. Occasionally, fields that generate correctly in isolation produce validation issues when combined with other schema on the same page, particularly if there are multiple overlapping types. The tester catches these interaction effects that a standalone generator can't predict.

Schema Types Worth Implementing by Site Type

Not every schema type is relevant to every site. These are the highest-priority types for common site categories, based on the rich results they unlock and their difficulty to implement.

Blog and content sites: Article schema on every post, with the recommended headline, image, datePublished, dateModified, and author, plus BreadcrumbList schema for navigation structure. Article markup helps Google understand your content type, title, dates, and authorship.

Local businesses: LocalBusiness schema (or a specific subtype like Dentist, Plumber, Restaurant) with full NAP, geographic coordinates, opening hours, and a link to the Google Maps listing. This is the highest-impact schema type for local rankings.

E-commerce: Product schema with name, image, description, brand, and offers (including price and availability). AggregateRating added to Product schema enables star ratings in shopping results. Review schema on individual review pages.

Informational guides: Article schema is the main fit. Two types that were once recommended here no longer produce rich results in Google Search: HowTo rich results were retired in 2023, and Google's documentation now states that FAQ rich results are no longer shown, a change that took effect in May 2026. Structure step-by-step and Q&A content clearly for readers, without relying on those markup types for an enhanced listing.

For a broader understanding of how schema markup works, which rich results each type unlocks, and the full strategic picture of structured data in SEO, the guide on what schema markup is and how it earns rich results covers the foundational concepts this guide assumes you have. If you're approaching schema for the first time, start there before working through the validation specifics here.