JSON vs XML

Definition and Usage

JSON and XML both store structured data as text. In this JSON tutorial, the focus is why JSON became the usual choice for web APIs: smaller payloads, typed values, and a direct map to objects in JavaScript.

XML still wins where tags, attributes, namespaces, or document markup are required (SOAP, RSS, SVG, Office). For REST-style JSON APIs, learn JSON first.

Same Data, Two Formats

One person record. JSON uses braces and typed tokens; XML uses open/close tags (and every element value starts as text).

{
  "name": "Ada",
  "age": 36,
  "active": true,
  "skills": ["math", "code"]
}

<person>
  <name>Ada</name>
  <age>36</age>
  <active>true</active>
  <skills>
    <skill>math</skill>
    <skill>code</skill>
  </skills>
</person>

Key Differences

• Syntax JSON: { } / [ ] and quoted keys. XML: nested tags and optional attributes.
• Types JSON has string, number, boolean, null, object, array. XML element content is text until validated or cast.
• Size JSON is usually more compact—no repeated closing tag names.
• Namespaces XML supports namespaces and attributes. JSON does not; use normal properties for metadata.
• Web APIs JSON is the default for REST and browser fetch. XML remains common in SOAP and document formats.
• Parsing In JavaScript: JSON.parse / JSON.stringify. XML needs a DOM/parser API.

Schemas for JSON

If you know XSD for XML: JSON Schema plays a similar role for JSON. A schema is itself JSON that declares expected types and structure so tools can validate payloads.

{
  "type": "object",
  "required": ["name", "age"],
  "properties": {
    "name": { "type": "string" },
    "age": { "type": "integer" },
    "active": { "type": "boolean" },
    "skills": {
      "type": "array",
      "items": { "type": "string" }
    }
  }
}

Examples

Use View Output for a quick result, or Try It Yourself to edit and run in the browser.

const text = `{
  "name": "Ada",
  "age": 36,
  "active": true,
  "skills": ["math", "code"]
}`;

const person = JSON.parse(text);
console.log(person.name);
console.log(person.age);
console.log(person.skills[0]);

Ada
36
math

const jsonText = JSON.stringify({
  name: "Ada",
  age: 36,
  active: true
});

const xmlText =
  "<person>" +
  "<name>Ada</name>" +
  "<age>36</age>" +
  "<active>true</active>" +
  "</person>";

console.log("JSON length:", jsonText.length);
console.log("XML length:", xmlText.length);
console.log(jsonText);

JSON length: 37
XML length: 67
{"name":"Ada","age":36,"active":true}

const person = JSON.parse(`{
  "name": "Ada",
  "age": 36,
  "active": true
}`);

console.log(typeof person.name);   // string
console.log(typeof person.age);    // number
console.log(typeof person.active); // boolean
console.log(person.age + 1);       // 37

string
number
boolean
37