What Is JSON?

What does JSON mean?

JSON stands for JavaScript Object Notation. It is a plain text format. It was born from the JavaScript language, but almost every language can read it. Think of it as a neat form with labels and answers, like "name: Sam".

Why is it used?

• Websites and apps use it to send data to each other. A system that lets programs talk is called an API.
• It is used in settings files, such as package.json or composer.json.
• It is easy for people to read and easy for computers to read.

What it looks like

{
  "name": "Sam",
  "age": 12,
  "student": true,
  "hobbies": ["chess", "football"],
  "address": {
    "city": "Pune"
  }
}

This describes one person. Each line is a pair: a name (called a key) and its value.

The building blocks

• Object: a group of pairs inside curly braces { }.
• Array: a list inside square brackets [ ].
• String: text inside double quotes, like "Sam".
• Number: a number with no quotes, like 12.
• Boolean: true or false.
• null: means "nothing here".

Rules to remember

1. Keys must be in double quotes. Single quotes are not allowed.
2. Separate items with commas.
3. Do not put a comma after the last item.
4. Comments are not allowed in plain JSON.
5. Every opening bracket needs a closing one.

How to check your JSON

1. Copy your text.
2. Paste it into a JSON validator. This is a free online tool that finds mistakes. Many code editors check JSON as you type.
3. Fix any line it points to.

Warning: Do not paste private data, such as passwords, into online tools.

If a settings file on your hosting will not load, ask support for help.

Quick recap

• JSON is a text format for sharing data.
• It uses key and value pairs, objects and arrays.
• Keys and text use double quotes.
• Watch your commas and brackets.
• Use a validator to find mistakes.