Schema Markup Debugger
Validate, inspect and improve your structured data.
Schema input
Paste JSON-LD or HTML containing JSON-LD script blocks.
Validation report
Issues, schema types and improvement suggestions.
Ready to inspect your schema
Paste your markup and run validation to see the report.
Syntax validation
Checks JSON parsing, malformed blocks and invalid structures.
Schema inspection
Inspects @context, @type, nested objects and @graph nodes.
Property audit
Checks common fields and selected rich-result requirements.
Actionable guidance
Highlights likely issues and practical correction suggestions.
Free JSON-LD Validator & Schema Markup Debugger
Validate your structured data with the FastTL Schema Markup & JSON-LD Debugger. Check JSON syntax, inspect schema types and properties, identify potential issues, and improve your structured data without an API key.
How to Use the JSON-LD Validator
- Paste your JSON-LD structured data into the editor.
- Run validation to inspect JSON syntax and schema structure.
- Review detected schema types, errors, warnings, and suggestions.
- Format your JSON-LD or download the validation report.
JSON-LD Syntax Checker
Check for common JSON syntax problems, including missing commas, invalid quotation marks, mismatched brackets, and malformed JSON objects.
Schema Markup Testing and Property Checks
Inspect @context, @type, @id, nested objects, and commonly used schema properties. Review potential missing fields based on supported schema presets.
Validate Multiple JSON-LD Blocks
Inspect multiple JSON-LD script blocks in HTML and identify potential structural issues across detected schema nodes.
Common Schema Markup Errors
- Missing or incorrect
@context - Missing or invalid
@type - Malformed JSON syntax
- Potentially missing schema properties
- Duplicate
@idvalues - Incomplete or inconsistent structured data
Frequently Asked Questions
What is a JSON-LD validator?
A JSON-LD validator checks whether structured data can be parsed and helps identify potential problems with its structure and properties.
Is this schema markup testing tool free?
FastTL’s browser-based debugger is designed to perform its included checks without requiring an API key.
Does valid JSON-LD guarantee Google rich results?
No. Valid JSON syntax does not guarantee Schema.org compliance, Google rich-result eligibility, or improved rankings. Use Google’s Rich Results Test for supported rich-result features.
Can I check multiple JSON-LD blocks?
Yes. The tool can inspect multiple JSON-LD script blocks found in the HTML you provide.
Does the tool send my schema data to an external AI API?
No. The included validation runs in your browser and does not require an external AI API.
Important: This tool provides heuristic checks, not a complete official Schema.org validation or Google eligibility assessment.