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JSON / Code Tools

Validate. Inspect. Understand.

Syntax check, schema validation, tree view, JSONPath, and diff — all in your browser.

JSON Input
Validation Results
Paste or type your JSON here...
EmptyValidateCtrl/⌘+Shift+VValidate

How to validate JSON online

  1. Open JSON Validator

    Go to json-validator.hanoon.app in your browser.

  2. Paste your JSON

    Paste or type your JSON data into the input editor.

  3. Check the result

    Validation runs automatically. Errors are highlighted with line numbers and descriptions so you can fix them quickly.

What is JSON validation?

Syntax validation rejects comments and trailing commas: {"age":18,} fails, while {"age":"18"} is valid JSON. Passing syntax does not mean the data satisfies a JSON Schema.

What is JSON Schema validation?

With schema {"type":"object","properties":{"age":{"type":"integer"}},"required":["age"]}, {"age":"18"} fails and {"age":18} passes. Choose Draft 4, Draft 7, or 2020-12 to match your schema. Numbers that cannot be represented safely stop schema validation with a precision error.

How does the tree view work?

The tree view displays your JSON as an expandable and collapsible hierarchy, letting you navigate nested structures and search for specific keys or values.

Is my data sent to a server?

No. All validation and processing happens entirely in your browser. Your data never leaves your device.

What is JSONPath?

For {"users":[{"name":"Ada"},{"name":"Lin"}]}, $.users[0].name or the JSON Pointer /users/0/name returns "Ada". Simple comparison filters are supported; method calls and prototype access are blocked.