Free tool

JSON Formatter and Validator

Paste your JSON to format, minify, or validate it instantly. Syntax highlighting, tree view, and error detection included. Free, no signup required.

What Is JSON?

JSON (JavaScript Object Notation) is a text-based data format that has become the standard for data exchange on the web. Originally derived from JavaScript, JSON is now language-independent and supported by virtually every programming language. It uses two primary structures: objects (collections of key-value pairs wrapped in curly braces) and arrays (ordered lists of values wrapped in square brackets).

JSON supports six data types: strings, numbers, booleans, null, objects, and arrays. Its simplicity and readability make it the preferred choice for REST APIs, configuration files, NoSQL databases like MongoDB, and front-end/back-end communication.

How to Format JSON

Formatting (or "pretty-printing") JSON adds indentation and line breaks to make the data structure easier to read. This is especially useful when debugging API responses, reviewing configuration files, or sharing data with teammates.

  1. 1. Paste your JSON into the input field above.
  2. 2. Click "Format" to pretty-print with 2-space indentation.
  3. 3. Use "Minify" to remove all whitespace for a compact, production-ready output.
  4. 4. Toggle "Tree" view to explore nested structures visually with expandable nodes.

Common JSON Errors and How to Fix Them

Trailing commas

JSON does not allow a comma after the last element in an object or array. Remove the comma before the closing bracket or brace.

Single quotes

JSON requires double quotes for all strings and keys. Replace single quotes with double quotes throughout your data.

Unquoted keys

Unlike JavaScript objects, JSON keys must always be wrapped in double quotes.

Comments

JSON does not support comments. Remove any lines starting with // or blocks wrapped in/* */. If you need comments, consider using JSONC or JSON5 formats instead.

JSON vs XML

Both JSON and XML are used for data exchange, but they differ in syntax, verbosity, and use cases. JSON is more compact, easier to parse in JavaScript, and has become the default for modern web APIs. XML is more verbose but supports attributes, namespaces, and schemas, making it suitable for document markup and enterprise integrations.

FeatureJSONXML
SyntaxKey-value pairsTags and attributes
ReadabilityMore compactMore verbose
Data typesString, number, boolean, null, array, objectAll values are strings
CommentsNot supportedSupported
Common useREST APIs, config filesSOAP APIs, document formats

Frequently Asked Questions

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