JSON Formatter & Validator

What is JSON?

JSON (JavaScript Object Notation) is a lightweight data interchange format that's easy for both humans and machines to read. It's the standard for REST APIs, configuration files, and data storage across nearly every programming language.

Common JSON validation errors

Trailing commas

JSON does not allow a comma after the last item in an object or array. {"name": "test",} is invalid. Remove the trailing comma.

Single quotes

JSON requires double quotes for strings. {'name': 'test'} is invalid. Use "name": "test" instead.

Unquoted keys

All object keys must be double-quoted strings. {name: "test"} is invalid. Use "name": "test".

Missing commas

Every element in an array or property in an object must be separated by a comma. A missing comma between values will trigger an "unexpected token" error.

Unescaped special characters

Control characters, backslashes, and double quotes inside strings must be escaped. For example, a literal tab should be \t and a newline should be \n.

How to use this tool

Paste your JSON into the input area. The tool validates it automatically and shows any errors with the exact line and column number. Use the Format button to pretty-print the JSON with consistent indentation, or Minify to compress it onto a single line.

Press Ctrl+Enter (or Cmd+Enter on Mac) while the input is focused to format instantly.

Format vs minify

Format (pretty-print)

Adds indentation and line breaks so the structure is easy to read. Use this when inspecting API responses, debugging configuration files, or reviewing data structures.

Minify

Strips all unnecessary whitespace, producing the smallest possible output. Use this when embedding JSON in URLs, storing it in databases, or reducing payload size for API requests.

JSON data types

JSON supports six data types:

• String: text wrapped in double quotes ("hello")
• Number: integers or decimals, no quotes (42, 3.14)
• Boolean: true or false (lowercase, no quotes)
• Null: null (lowercase, no quotes)
• Array: an ordered list of values ([1, 2, 3])
• Object: a collection of key-value pairs ({ "key": "value" })

Note that JSON does not support comments, undefined, functions, dates (use ISO 8601 strings instead), or single-quoted strings. These are common sources of validation errors when converting from JavaScript objects to JSON.

When you would use this

• Inspecting API responses from curl or Postman that arrive as a single line
• Validating JSON configuration files (package.json, tsconfig.json, terraform plans) before committing
• Debugging webhook payloads or log entries that contain JSON
• Cleaning up JSON before pasting it into documentation or tickets
• Minifying JSON for use in environment variables, URL parameters, or database fields