JSON is lighter, faster to parse, and natively supported in every browser — making it the standard for REST APIs and data exchange. XML is more expressive, supports attributes and namespaces, and remains dominant in enterprise systems (SOAP, XSLT, SVG, RSS). For new web APIs, choose JSON. For document processing, configuration standards, or legacy systems, XML is still the right tool.
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Convert XML to JSON →The same data in JSON and XML
Here's the same user record in both formats:
// JSON — 118 characters
{
"user": {
"id": 42,
"name": "Alice Smith",
"email": "alice@example.com",
"roles": ["admin", "editor"]
}
}
<!-- XML — 195 characters -->
<user>
<id>42</id>
<name>Alice Smith</name>
<email>alice@example.com</email>
<roles>
<role>admin</role>
<role>editor</role>
</roles>
</user>
JSON uses 40% fewer characters for the same data here. In large API responses or bulk data transfers, this difference in payload size compounds significantly.
Quick comparison
| Feature | JSON | XML |
|---|---|---|
| Syntax | Key-value pairs, arrays, objects | Element tags with attributes and text nodes |
| Verbosity | Compact — no closing tags | Verbose — every element needs a closing tag |
| Comments | Not supported | Supported (<!-- comment -->) |
| Data types | Number, boolean, null built-in | Everything is text by default |
| Attributes | No equivalent | Metadata on elements (<tag attr="v">) |
| Namespaces | Not supported | Supported (xmlns) |
| JavaScript support | Native (JSON.parse) | Requires DOMParser or library |
| Schema validation | JSON Schema (Draft 2020-12) | XSD, DTD, RELAX NG |
| Query language | JSONPath (RFC 9535) | XPath, XQuery |
| Transformation | No built-in standard | XSLT |
| Common use cases | REST APIs, NoSQL databases, config | SOAP, enterprise, documents, SVG, RSS |
Where JSON wins
Where XML wins
Element attributes
XML allows metadata to be attached to elements as attributes, which has no clean JSON equivalent:
<price currency="USD" tax="0.1">29.99</price>
In JSON you'd need a separate object or a convention to express this:
{ "price": { "value": 29.99, "currency": "USD", "tax": 0.1 } }
Mixed content
XML can contain a mix of text and child elements in the same node — essential for document formats like HTML-like content. JSON has no native concept for this.
XSLT transformations and XPath queries
XML has a mature ecosystem for transformation (XSLT), querying (XPath), and validation (XSD schemas). These are powerful tools when you need to transform XML documents into other formats or enforce complex structural constraints.
Namespaces
XML supports namespaces to combine elements from different vocabularies in a single document — essential for SOAP web services and formats like SVG embedded in HTML.
When to use JSON
- REST APIs and web services — the universal standard
- Configuration files for JavaScript tooling (package.json, tsconfig.json)
- Data exchange between web applications
- Storage in NoSQL databases (MongoDB, Firestore, DynamoDB)
- Any scenario where payload size and parsing speed matter
When to use XML
- SOAP web services (legacy enterprise integrations)
- Healthcare data interchange (HL7 FHIR can use XML or JSON, but many systems are XML-first)
- Office document formats (DOCX, XLSX are ZIP files containing XML)
- RSS and Atom feeds
- SVG graphics and MathML
- Any scenario requiring XSLT transformation or XSD validation
YAML — the third option for configuration
YAML is a superset of JSON that adds human-friendly syntax: comments, multi-line strings, and indentation-based structure instead of braces. It's the dominant format for configuration files — Kubernetes manifests, Docker Compose, GitHub Actions workflows, Ansible playbooks. Use the JSON to YAML converter to convert your JSON config to YAML format.
To format or validate JSON from API responses, use the JSON Formatter or JSON Validator.
Frequently Asked Questions
Is JSON better than XML?
For most modern web APIs and data exchange between applications, JSON is the better choice — it's more compact, easier to read, and natively supported in JavaScript. XML has advantages for document-centric content, scenarios requiring element attributes, XML namespaces, or XSLT transformations. Neither format is universally better; the right choice depends on the use case.
Why is JSON more popular than XML for APIs?
JSON is more compact (smaller payload size), directly parseable in JavaScript without a library, and easier for humans to read and write. REST APIs adopted JSON as the de-facto standard because it maps naturally to JavaScript objects and is simpler to work with than XML's verbose tag-based syntax.
Can JSON replace XML completely?
Not completely. XML has features JSON lacks: element attributes, namespaces, mixed content (text and elements together), XSLT for transformations, and XSD schemas. Enterprise systems, document stores, and SOAP web services still rely on XML. JSON is dominant for new web APIs, but XML remains the standard in healthcare (HL7), finance (FIX/SWIFT), and enterprise integration.
What about YAML — how does it compare to JSON and XML?
YAML is a superset of JSON that adds comments, multi-line strings, and a more human-friendly syntax using indentation instead of braces. It's the standard for configuration files (Kubernetes, Docker Compose, GitHub Actions). YAML is harder to parse correctly than JSON due to its flexibility, so it's preferred for files humans write and read rather than for data exchange between systems.
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