Step-by-step guides
Workflows for uploading, validating, correcting and comparing schema, including official Google documentation.
Browse guides →01. Your schema markup
Input stays on this deviceSingle file opens in editor. Multiple files or ZIP run a bulk check. No server upload.ZIP up to 20 MB compressed · supported extracted files up to 25 MB total · 1 MB per file · no fixed entry-count limit.
0 characters1M characters per file · safety limit
🔒 No pasted markup is sent to a server. The checker runs locally; support-status rules are fetched as a static file from this website.
02. Schema Doctor results
Ready to check—Errors
—Warnings
—Entities found
Top 3 things to fix first
Detected schema types
Syntax: not checkedRun a check to see type details.
Findings & suggested fixes
Ready when you are
Paste markup or load an example, then run the checker.
Auto-fix preview
Before
After
Interface controls translated. Technical diagnostic text, articles and guides remain in English.
Schema.org vocabulary checks run only when the official offline snapshot is installed; expected types, inherited properties, domainIncludes and rangeIncludes are advisory, not proof of full semantic validity or Google eligibility. Schema.org defines 800+ vocabulary types; the full vocabulary; Google-specific feature checks remain focused. Use the official Schema Markup Validator for broad vocabulary checks and Google's Rich Results Test.
Batch review · No account quota
03. Bulk files, corrections & combined report
Upload several files or a ZIP above. Work stays in this browser. Each file is checked separately; download a reviewed ZIP with safely edited and unchanged files clearly separated.
No batch selected.
No daily quotas or sign-up. A single file is capped at one million characters and there is no fixed file-count or ZIP entry-count quota. Repeat batches whenever you like. Browser memory and archive-size safeguards still apply. ZIP entries such as images, scripts and folders are ignored. A 25 MB combined extracted-content limit applies. For each result, use Preview suggested fix to see Before / After; only Approve & apply suggestion changes a high-confidence spelling typo. Auto-fix never invents missing business facts.
Know if your schema is valid, useful & supported.
Paste code or upload JSON-LD, HTML and ZIP batches. Discover what is wrong, why it matters and how to fix it, with official references and a dated Google status snapshot — entirely in your browser.
Go to schema checker ↓✓ Files never leave your device✓ 100% free · No login · No daily quota✓ Dated Google statusGoogle data: loading…Schema.org vocabulary: checking offline snapshot…
Learn by doing
Professional guides and in-depth blog
Long-form blog
Practical 1,200+ word articles covering every major checker feature, with examples and relevant sources.
Read articles →Schema Hierarchy Explorer
Search Schema.org types, explore parent and child relationships, and read property explanations here on our site.
Explore Schema.org types →Google status tracker
Google feature support and retirement status, with documentation URLs and manual verification dates.
View tracker →Three layers, one view
Understand what the markup actually means
JSON syntax
Detect malformed JSON and JSON-LD blocks in HTML, with practical hints for fixing mistakes.
Focused schema rules
Check common fields in Article, Product, Organization, LocalBusiness and BreadcrumbList. Not a full vocabulary validator.
Google support snapshot
Show supported or retired Google features with official documentation links and dated notes.
Useful distinction: syntactically valid JSON-LD can still fail Google's feature-specific requirements, and passing local checks never guarantees a rich result. See the two validators explained guide.
New browser-local tools
Generate, convert, compare and inspect schema & metadata
Sixteen tools are available inside Schema Support Checker, with dedicated pages and no data upload.
JSON-LD Generator
Build JSON-LD for eleven Schema.org types using real field values, see live local checker feedback, and copy or download the output.
CSV to JSON-LD Bulk Converter
Map CSV columns to Product or LocalBusiness markup, validate up to 500 rows, and download per-row JSON-LD plus a report in a ZIP.
JSON-LD Formatter & Minifier
Format, minify, or sort JSON-LD keys without changing facts or array order; find invalid JSON syntax before publishing.
Schema Type Finder
Describe your page or choose a subject to find offline Schema.org types, with optional Google feature and rich-result candidate filters.
@graph / @id Visualizer
View labeled JSON-LD nodes, directed @id relationships, duplicate IDs, unresolved references and isolated nodes in a browser-local diagram.
Microdata / RDFa and JSON-LD Converter
Convert simple Schema.org HTML Microdata or RDFa to JSON-LD, or generate basic HTML markup from JSON-LD, locally with explicit subset limits.
Schema Diff Checker
Compare two JSON-LD documents and inspect added, removed and changed JSON properties with a downloadable report.
Property Coverage Scorecard
Compare present JSON-LD fields with dated Google required and recommended property lists; no rich-result guarantee.
Meta / Open Graph / Twitter Card Checker & Generator
Inspect HTML title, description, canonical and social tags, or generate escaped meta tags from your own page facts.
SERP Preview Tool
Preview page titles and descriptions on desktop or mobile with advisory length and pixel-width checks; no Google appearance guarantee.
robots.txt Tester
Paste robots.txt and test a URL path for Googlebot, Bingbot or a custom user-agent with local rule matching.
Sitemap Validator & Generator
Validate pasted or uploaded XML sitemaps and sitemap indexes, or generate sitemap.xml from supplied URLs.
llms.txt Generator & Validator
Create and inspect voluntary llms.txt Markdown files locally; no AI indexing or ranking promise.
hreflang Checker & Generator
Generate HTML and XML hreflang annotations; inspect page tags and verify reciprocal links only across supplied pages or sitemap entries.
Date / Duration / Currency Helper
Validate dates, timezone offsets, ISO 8601 durations and ISO 4217 currency codes; generate factual Schema.org JSON-LD examples.
Agency Report Generator
Build branded, browser-local client audit reports from supplied findings with Before/After notes, printable HTML and PDF via browser print.
Quick answers
Frequently Asked Questions
Straight answers about file limits, privacy, safe fixes and Google results.
What does Schema Support Checker actually check?
It checks pasted JSON-LD or JSON-LD scripts inside HTML for JSON syntax problems and a focused set of structured-data issues. It also explains selected Google feature statuses. It is not a complete Schema.org validator.
Is Schema Support Checker free, and do I need an account?
All checker functions are free. There is no account, subscription, paid plan or daily request quota. Browser memory and file-size safety limits still apply.
Does my uploaded HTML or ZIP file leave my computer?
No. Schema checking, file reading, safe-fix previews and report downloads run inside your browser. The website still loads ordinary site assets, and optional production advertising can make separate third-party requests as explained in the Privacy Policy.
What is the maximum ZIP upload size?
A ZIP archive may be up to 20 MB compressed. Supported files inside it may total up to 25 MB extracted, and each supported file may be up to 1 MB. There is no fixed entry-count quota. Large archives may still exceed browser memory limits.
Which file types can I upload?
The checker accepts .json, .jsonld, .html, .htm and .zip. Inside ZIP archives, only supported JSON and HTML files are checked; unrelated files and folders are skipped.
Can I check thousands of files in one ZIP?
There is no fixed file-count cap, and ZIP64 entry counts are supported. Whether thousands of files complete successfully depends on the 20 MB compressed, 25 MB extracted and 1 MB per-file limits, plus available browser memory.
We are here to help
Need help with a tool?
Found a bug, unexpected result, or problem downloading a corrected file? Contact our support team. We welcome clear reports and suggestions.
Have a suggestion for improving or changing any of our tools? Please don't hesitate to contact our support team. We'd be happy to hear from you. Thank you for your feedback!
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Schema Support Checker Edge extension and Windows app are coming soon.
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Find structured data issues, understand Google guidance and apply safe fixes on your device.