Private, browser-local preflight

Structured Data Validator

Paste JSON-LD to find JSON syntax errors, duplicate keys, malformed JSON-LD keywords, and likely spelling mistakes in common Schema.org terms.

Your markup stays here. Validation runs in this browser. The tool does not upload code, fetch URLs, resolve remote contexts, or store your input.

1. Paste JSON-LD

Use raw JSON or one complete <script type="application/ld+json"> block. Limit: 200,000 code units.

0 / 200,000 code units

2. Local report

Paste markup, then choose Validate data.
—Errors
—Warnings
—Typed entities
—UTF-8 bytes
No report yet

    Diagnostics will include a severity, JSON path, and explanation.

    What this validator checks

    First it checks JSON grammar and duplicate object names. Then it inspects JSON-LD document shape and common keyword values such as @context, @type, @id, @graph, @value, and @list. With a Schema.org context, it also offers conservative spelling hints from an offline common-term snapshot.

    How to read the report

    • Error: invalid JSON or a shape that conflicts with the local JSON-LD checks.
    • Warning: suspicious or incomplete markup worth reviewing.
    • Information: a limit of local analysis, including an unknown vocabulary term.

    Exact JSON paths help you find nested values. Formatting changes whitespace and embedding-sensitive escaping only; it does not repair semantics. Before offering formatted output, the tool rejects non-finite, signed-zero, unsafe-integer, underflowed, or over-precise number tokens when the browser would serialize a different mathematical value.

    Limits and final verification

    This is not a full JSON-LD expansion or RDF processor. Context aliases, term definitions, containers, base/vocabulary resolution, framing forms, RDF conversion, and remote-context behavior are deliberately unchecked. It never reads a live page, checks visible-content parity, or applies a search engine's current feature rules. Unknown terms may be valid extensions or newer Schema.org releases.

    Check the final markup with Schema.org
    Check relevant Google features separately