JSON Formatter & Validator

What is JSON? (JavaScript Object Notation)

JSON is the universal language of the modern web. It is a lightweight, text-based format used to store and transport data between a server and a web application. While it originated from JavaScript, it is language-independent, meaning it can be read by Python, Java, PHP, and almost every other programming language.

Why Use JSON?

• Readable: It is easy for humans to write and easy for machines to parse.
• Fast: Because it is lightweight, it transmits over the internet much faster than older formats like XML.
• Structured: It supports complex, nested data, making it perfect for representing user profiles, product catalogs, and settings.

Strict JSON Syntax Rules

To be "Valid JSON," your data must follow these strict rules. Even a single misplaced character will cause a Parse Error.

1. Key/Value Pairs: Data is organized in pairs: "key": "value".
2. Double Quotes are Mandatory: * ✅ "name": "John"
   • ❌ 'name': 'John' (Single quotes are invalid).
3. Strings and Keys: Both keys and string values must be enclosed in double quotes.
4. Data Types: JSON supports six data types:
   • String ("Hello")
   • Number (42, 3.14)
   • Object ({ })
   • Array ([ ])
   • Boolean (true/false — must be lowercase)
   • Null (null — must be lowercase)

Common JSON Errors (and How to Fix Them)

Even experienced developers run into these common syntax traps:

• Trailing Commas: You cannot have a comma after the last item in an object or array.
  • ❌ {"id": 1, "name": "Alice",}
  • ✅ {"id": 1, "name": "Alice"}
• Comments: JSON does not support comments (// or /* */). If you include them, the file will break.
• Unquoted Keys: In JavaScript, you can write {name: "John"}. In JSON, the key must be quoted: {"name": "John"}.
• Case Sensitivity: True, False, and NULL are invalid. They must always be lowercase: true, false, null.

Use Our JSON Formatter Tool

Manually finding a missing comma in 500 lines of code is nearly impossible. Use our Free JSON Formatter to:

• Validate: Instantly find and highlight syntax errors.
• Beautify: Turn "minified" (squashed) JSON into a readable, indented structure.
• Minify: Compress your JSON to save space and improve website loading speeds.

Frequently Asked Questions