JSON Formatter & Validator

Paste raw JSON to validate, beautify, or minify instantly with clear error messages.

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What Is JSON?

JSON (JavaScript Object Notation) is a lightweight, human-readable text format for representing structured data. Created by Douglas Crockford in the early 2000s, it is now the universal data interchange format for web APIs, configuration files, and data storage. JSON supports six data types: strings (double-quoted), numbers, booleans (true/false), null, objects (key-value pairs), and arrays.

Why Format JSON?

Beautify (pretty-print) adds indentation and line breaks, making nested data structures readable by humans. Use beautified JSON when debugging API responses, reviewing configuration, or documenting data structures. Minify removes all unnecessary whitespace, reducing file size — ideal for production API responses and data transmission where every byte matters. Validation checks syntax without changing the output, confirming your JSON is well-formed before use.

Common JSON Syntax Errors

  • Single quotes: JSON requires double quotes for all strings. Single quotes cause parse errors.
  • Trailing commas: [1, 2, 3,] is invalid — the last element must have no comma.
  • Unquoted keys: {name: "value"} is invalid. Object keys must be quoted strings.
  • Comments: JSON has no comment syntax. // comment will break parsing.
  • Undefined values: JavaScript's undefined is not valid in JSON — use null.

JSON in Real Projects

REST APIs, NoSQL databases (MongoDB, Firebase), package.json in Node.js, tsconfig.json, VS Code settings, and browser extension manifests all use JSON. Understanding and correctly formatting JSON is a foundational skill for web developers, data analysts, and anyone working with modern software systems.