JSON Viewer & Formatter

Paste or upload JSON to validate, format with syntax highlighting, and explore the interactive tree view. Runs entirely in your browser.

JSON Viewer & Formatter

Paste or upload your JSON to validate, format and explore it with interactive syntax highlighting. Everything runs in your browser — your data never leaves your device.

Input

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What is JSON?

JSON (JavaScript Object Notation) is a lightweight, text-based data format that is easy for humans to read and write, and easy for machines to parse and generate. It is the de-facto standard for data exchange in web APIs, configuration files, databases, and more.

A JSON document can contain six types of values: strings ("hello"), numbers (42), booleans (true / false), null, arrays ([ ... ]) and objects ({ ... }).

JSON Example

{
  "user": {
    "id": 1,
    "name": "Alice Smith",
    "email": "alice@example.com",
    "roles": ["admin", "editor"],
    "preferences": {
      "theme": "dark",
      "notifications": true
    },
    "lastLogin": null
  }
}

How to Use the JSON Viewer

  1. 1

    Paste or upload your JSON

    Copy your JSON from your API response, config file, or anywhere else and paste it into the editor above. Or click "Upload file" to load a .json file from your computer. You can also drag & drop the file directly onto the editor.

  2. 2

    Click "Format & Validate"

    Hit the blue button to run validation. If your JSON has syntax errors the tool will show a descriptive error message. If it's valid, you'll see the formatted output below.

  3. 3

    Explore with Tree or Raw view

    Switch between Tree view (interactive, collapsible nodes) and Raw view (plain formatted text with indentation). In Tree view click any ▶ arrow to collapse or expand a node.

  4. 4

    Copy or Download

    Use the "Copy" button to copy the formatted JSON to your clipboard, or "Download" to save it as a formatted.json file.

Frequently Asked Questions

Is my JSON data stored on your servers?▼

No. All processing happens entirely inside your web browser using JavaScript. Your data is never sent to our servers, logged, or stored anywhere.

What is the difference between a JSON viewer and a JSON formatter?▼

A JSON formatter simply re-indents and prettifies the raw JSON text. A JSON viewer goes further by rendering the data as an interactive tree where you can expand and collapse branches, making it easier to navigate large or complex documents.

Why is my JSON invalid?▼

Common causes of invalid JSON include: using single quotes instead of double quotes, trailing commas after the last element, unquoted keys, or JavaScript-specific values like undefined, Infinity, or NaN. The error message shown by this tool will include the exact position of the first syntax error.

What is the maximum file size supported?▼

Because processing happens in your browser, the limit is your browser's available memory. In practice, files up to several megabytes work without issues. Very large files (>50 MB) may be slow to render in tree view.

Can I use this tool offline?▼

Yes. After loading the page once, the JavaScript that powers the tool is cached by your browser and works without an internet connection.

Is this tool free?▼

Yes, completely free with no registration or sign-up required. It is supported by non-intrusive advertising.

Frequently Asked Questions

What is a JSON Viewer?

A JSON Viewer lets you paste, validate, and explore JSON data with syntax highlighting and a collapsible tree view, making it easy to read and debug complex JSON structures.

Is my JSON data stored on your servers?

No. All processing runs entirely in your browser using JavaScript. Your data never leaves your device.

What is JSON?

JSON (JavaScript Object Notation) is a lightweight data-interchange format, easy for humans to read and write and easy for machines to parse. It is the standard format for APIs and configuration files.

How do I validate JSON?

Paste your JSON into the editor and click Format & Validate. The tool instantly shows whether your JSON is valid and highlights any syntax errors.

Can I upload a JSON file?

Yes. Use the upload button to load any .json file directly from your computer and explore it in the tree view.