What is the difference between JSON validation and JSON schema validation?

JSON validation checks that a string is parseable, correctly-formed JSON. JSON schema validation additionally checks that the data matches a declared structure — correct field names, types, and constraints.

Does FixTools validate JSON against a custom schema?

FixTools validates JSON syntax. For schema validation against a custom JSON Schema (draft-07, 2019-09, 2020-12), use a dedicated schema validator like ajv in Node.js or jsonschema.net online.

Why should I validate JSON syntax before schema validation?

Schema validators typically throw unhelpful errors when the input is not even parseable JSON. Syntax-validating first gives you clearer error messages and a shorter debugging cycle.

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JSON Schema Validator

JSON schema validation checks that your JSON data matches a defined schema — required fields, data types, value constraints. Before you can do schema validation, the JSON must be syntactically valid. FixTools validates your JSON syntax instantly — a necessary first step for any schema validation workflow.

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Validate JSON syntax as a first step

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Clear error messages for invalid JSON

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Free and browser-based

JSON Tool

JSON Validator

All processing happens in your browser — your files are never uploaded to any server.

🚀Open JSON Validator

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How to use this tool

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Validate your JSON syntax with FixTools before running it through a schema validator.

How It Works

Step-by-step guide to json schema validator:

1
Check JSON syntax first
Paste your JSON into FixTools and validate it. Schema validators will reject or behave unpredictably with invalid JSON.
2
Fix any syntax errors
Correct errors identified by the syntax validator and re-validate until the JSON is clean.
3
Proceed to schema validation
With valid JSON in hand, test it against your JSON Schema using a schema validator like ajv, jsonschema.net, or your application's schema library.