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OpenAPI Validator

Paste an OpenAPI JSON document for a bounded local structure check. YAML and full schema validation are not supported.

In-browser processingNo account requiredPrivacy details ↗

JSON only; OpenAPI 3.0 or 3.1; maximum 1 MiB. This checks a small set of structural requirements, not the full specification.

    A QUICK WALKTHROUGH

    How to use this tool

    1. Paste an OpenAPI 3.0 or 3.1 JSON document up to 1 MiB.
    2. Run the local structure check.
    3. Review JSON, version, info, paths, operation, and responses findings.

    Limited structural validation

    Checks JSON syntax, OpenAPI 3.0.x or 3.1.x version, info title/version, paths object, operation objects, and non-empty responses.

    JSON only

    This tool does not parse YAML and does not validate the full OpenAPI schema or referenced documents.

    Local processing

    The pasted text is parsed in your browser and is not uploaded.

    GOOD TO KNOW

    Common questions

    Does it fully validate the OpenAPI specification?

    No. It checks only the listed structural requirements.

    Can I paste YAML?

    No. This first version accepts JSON only.

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    JSON Formatter

    Number and string tokens (including escapes and lone surrogates) stay verbatim. Duplicate keys stay present. Sorting compares decoded keys by UTF-16 order, keeping duplicate order stable. Positions use 1-based UTF-16 units. Validate mode keeps original whitespace and ignores sorting. UTF-8 byte counts and JSON/TXT exports replace literal lone surrogates with U+FFFD; escaped surrogate tokens remain unchanged. Processing stays in this browser. Nothing is uploaded.