What Is JSON?

JSON is a text-based format for exchanging structured data. It is deliberately simple: an object groups named values, while an array keeps an ordered list of values.

JSON values and structure

JSON supports strings, numbers, booleans, null, objects, and arrays. For example, this is valid JSON:

{
  "name": "4all.tools",
  "active": true,
  "tags": ["json", "developer-tools"]
}

JSON is related to JavaScript, but it is not JavaScript code. JSON is a data notation with a deliberately limited syntax that many languages can read.

Common syntax errors

Property names and string values require double quotes. Standard JSON also does not allow comments or trailing commas. A missing comma, an extra comma, or an unmatched brace can make an otherwise useful document invalid.

APIs commonly use JSON for request and response bodies, and configuration files often use it because people can read it while programs can parse it. When a document is not accepted, use the JSON Formatter & Validator to locate syntax errors before sending it to an API or saving it as configuration.

Summary

JSON gives applications a portable way to exchange structured values. Learn its small set of syntax rules, then validate examples as you build them.