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Format, validate, and inspect JSON with a tree view.
Format, validate, and inspect JSON with a tree view.
Nextooly’s JSON Formatter & Validator is a full-featured JSON toolbox for developers. Paste or load JSON, then pretty-print it, minify it, or explore it in an interactive, collapsible tree view.
A built-in linter highlights syntax errors in real time and pinpoints exactly where parsing fails. You can also auto-generate a JSON Schema from your data, validate JSON against the active schema, and download either the formatted JSON or the inferred schema for later use.
Example
Input: The source text, file, or settings you want to work with.
Output: A clean json formatter & validator result ready for the next step.
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Does this JSON formatter upload my data to any server?
No. All formatting, minifying, schema generation, validation, and tree rendering happen entirely in your browser. Your JSON never leaves your device.
Why do I see a syntax error while typing?
The tool includes a real-time JSON linter. As soon as the input becomes invalid JSON, it highlights the exact position of the error and shows a descriptive message.
What does the Auto-format option do?
When enabled, the tool automatically pretty-prints your JSON whenever you modify the input. When disabled, formatting only happens when you click the Format button.
How does Generate Schema work?
The tool scans your JSON and automatically infers a JSON Schema describing its structure, including types, properties, arrays, and required fields. The generated schema can be viewed and downloaded.
What does Validate Schema do?
Validate Schema checks whether your input JSON matches the currently displayed schema. If any mismatch occurs, the tool shows the exact location and expected type.
Why is Tree View empty?
Tree View only appears when your JSON is valid. If the input cannot be parsed, the tree cannot be generated and a placeholder message is shown instead.
Can I open and format JSON files directly?
Yes. You can load .json or .txt files using the Open File button. The contents are loaded instantly into the input editor for formatting or validation.
What happens when I click Download?
The tool downloads the currently displayed panel: formatted JSON, generated schema, or raw JSON (in Tree mode). File names are set automatically based on the active view.
Why does Minify remove all whitespace?
Minify outputs compact JSON by removing spaces and line breaks. This is useful for APIs, storage, and reducing payload size.
2026-03-10
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