Side by side
JSONvsXML
What is the difference between JSON and XML?
Updated 2 min read7 differences
In short
Both write structured data as text: JSON is lighter and maps onto objects and arrays, while XML adds attributes, namespaces and schemas.
JSON
JavaScript Object Notation
JSON is a lightweight, text-based format for storing and exchanging structured data as key-value pairs and lists, readable by both humans and machines.
Read the page on JSONXML
Extensible Markup Language
XML (Extensible Markup Language) is a text format for structured data that uses nested tags you define yourself, readable by both people and machines.
Read the page on XMLJSON and XML compared
| Aspect | JSON | XML |
|---|---|---|
| Syntax | Braces, brackets and key-value pairs | Nested elements with opening and closing tags |
| Size | Compact | Wordier: every element is named twice |
| Data types | String, number, boolean, null, object, array | All text, unless a schema says otherwise |
| Attributes and namespaces | None | Both, for metadata and for mixing vocabularies |
| Comments | Not allowed | Allowed: <!-- … --> |
| Schemas | JSON Schema, optional | XSD and DTD, widely used |
| Typical uses | REST APIs, configuration, logs | SOAP, documents, SVG, RSS, industry standards |
The difference, explained
JSON writes data as objects in braces, arrays in brackets, and strings, numbers, booleans and null. XML writes it as a tree of named elements with opening and closing tags, which can also carry attributes, as in <price currency="EUR">9.90</price>. Both are plain text that people can read and every major language can parse.
JSON won for web APIs because it is short and fits the data structures programs already use: one call turns it into a JavaScript object or a Python dictionary. XML is wordier, but it was built for documents as well as data: it mixes text with markup, keeps its elements in order, separates vocabularies with namespaces, and can be checked against a schema with XSD and transformed with XSLT.
So XML is still everywhere it started: SOAP web services, office files such as .docx and .xlsx, SVG images, RSS feeds, Android layouts and many banking and government standards. JSON dominates REST APIs, configuration files, NoSQL databases and logs. JSON has a schema language too, JSON Schema, though validating against a schema is less of a habit than it is with XML.
Neither is faster or safer by nature, but each has a trap. XML parsers that resolve external entities can be abused to read files from the server, an attack called XXE, so that feature should be turned off. JSON has no comments and no date type, so dates travel as strings, usually in ISO 8601 form.
Which one should you use?
Choose JSON when…
- You are building or calling a web API.
- The data maps onto objects, arrays and simple values.
- Size and parsing speed in browsers and mobile apps matter.
Choose XML when…
- You exchange data with a system or standard that requires XML, such as SOAP or many banking formats.
- The content is a document, with text and markup mixed together.
- You need namespaces or strict validation against a schema.
The same order in JSON and in XML
{
"order": {
"id": 1042,
"currency": "EUR",
"items": [
{ "sku": "TEA-01", "quantity": 2 },
{ "sku": "MUG-07", "quantity": 1 }
]
}
}<order id="1042" currency="EUR">
<items>
<item sku="TEA-01" quantity="2"/>
<item sku="MUG-07" quantity="1"/>
</items>
</order>Readers ask
Has JSON replaced XML?
For new web APIs, largely yes. But XML remains the format of many standards, document types and older systems, and it isn't going away.
Can I convert between JSON and XML?
Usually, with care. XML attributes, mixed text and repeated elements have no single JSON equivalent, so converters make choices, and a round trip may not give back exactly what you started with.
Is JSON just JavaScript?
It is based on JavaScript's object syntax, and since 2019 every JSON text is also valid JavaScript. But JSON is stricter: keys need double quotes, and there are no comments, trailing commas or functions.