Free JSON Viewer & Formatter

Free Online JSON Viewer, Formatter and Validator

Use the FreeKitTools JSON Viewer to format, validate and inspect JSON data in a clear, readable layout. JSON (JavaScript Object Notation) is a common data format for APIs, configuration files, web applications and data exchange. Minified JSON can be difficult to inspect because the entire structure may appear on one line. This tool adds indentation, checks whether the input can be parsed, and offers a tree view for nested objects and arrays.

Format and validate JSON

Paste your JSON and choose Format & Validate. If the data is valid, the formatter produces a consistently indented version that is easier to read, copy and debug. If the JSON is invalid, the browser reports a parsing error where available. Common problems include missing commas, unquoted property names, trailing commas, mismatched braces, single quotes instead of double quotes, and comments that are not allowed in standard JSON.

Explore nested objects with tree view

JSON commonly contains objects, arrays, strings, numbers, booleans and null values nested inside one another. The tree view helps you explore these structures without scanning a long block of text. Expand and collapse object or array nodes to focus on the part of the data you need. This is useful when checking API responses, application settings, test fixtures and sample data.

How to use this JSON tool

1. Paste JSON into the input box or load the example.
2. Click Format & Validate to check syntax and produce readable output.
3. Use Minify JSON for a compact single-line representation.
4. Inspect the tree, copy the output or download it as a .json file.

JSON versus JavaScript objects

JSON is a data format with stricter syntax than JavaScript source code. JSON requires double-quoted strings and property names, does not support comments, and cannot contain functions or undefined values. A JavaScript object literal may be valid JavaScript but invalid JSON. If an API or configuration system expects JSON, use strict JSON syntax and validate the result before sending or deploying it.

Privacy and safe debugging

All parsing and formatting on this page happens in your browser. The entered JSON is not sent to a FreeKitTools processing endpoint. Still, avoid placing passwords, access tokens, private customer records or confidential production data into any tool unless you have permission and understand the environment. Large JSON files can consume significant memory, so use a local editor for very large datasets. Always check whether a value's type and meaning remain correct after making manual edits.