Quick Verdict
Use JSON when…
Use JSON for REST APIs, configuration files (package.json, tsconfig.json), NoSQL databases, browser localStorage, and any JavaScript/TypeScript project — parsing is trivial with `JSON.parse()`.
Use XML when…
Use XML when you need schemas for validation (XSD), namespaces for mixing vocabularies, comments in data files, XSLT transformations, SOAP web services, or working with legacy enterprise systems that expect XML.
JSON vs XML: Feature Comparison
| Feature | JSON | XML |
|---|---|---|
| Verbosity | Concise | Verbose (opening and closing tags) |
| Comments | Not supported | Supported |
| Schema validation | JSON Schema (separate spec) | XSD (built-in ecosystem) |
| Namespaces | Not supported | Full namespace support |
| Data types | String, number, boolean, null, array, object | Everything is text (types via XSD) |
| JavaScript parsing | Native (JSON.parse) | Requires DOM parser or library |
| Human readability | High | Moderate (tag noise) |
| XSLT transforms | Not applicable | Full XSLT support |
When JSON wins
- ✓Verbosity: Concise
- ✓Comments: Not supported
- ✓Schema validation: JSON Schema (separate spec)
When XML wins
- ✓Verbosity: Verbose (opening and closing tags)
- ✓Comments: Supported
- ✓Schema validation: XSD (built-in ecosystem)
Frequently asked questions
Is JSON replacing XML?
In web APIs, yes — REST+JSON has largely replaced SOAP+XML for new services. But XML is far from dead: Office Open XML (DOCX, XLSX, PPTX), SVG, RSS, Atom, Android layouts, Maven POM files, Spring configuration, and countless enterprise systems all use XML. JSON has the web; XML has depth and tooling for complex document formats.
Can JSON represent attributes like XML?
No — XML has both attributes and child elements, giving two ways to attach data to a node. JSON only has object keys and values. When converting XML to JSON, attributes are typically mapped to keys (often prefixed with @ by convention), but the roundtrip is lossy without a defined mapping standard.
Which is faster to parse?
JSON is generally faster to parse. V8 (Chrome/Node.js) has a highly optimized `JSON.parse()` implemented in native code. XML parsers must handle tag syntax, namespaces, and entity references, making them inherently more complex. For large datasets, JSON's parsing speed advantage is significant in JavaScript environments.
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