JSON vs XML: Which Data Format?
JSON is a lightweight, ubiquitous data format; XML is a verbose markup format with namespaces, schemas, attributes, and rich validation tooling.
JSON maps cleanly to objects and arrays, is compact, and dominates web APIs and config. XML is more verbose but offers namespaces, attributes, mixed content, XSD schema validation, and XPath/XSLT, persisting in enterprise, documents, and SOAP. JSON favors simplicity and web ubiquity; XML favors rich document structure and formal validation.
| JSON | XML | |
|---|---|---|
| Verbosity | Compact | Verbose |
| Schemas | JSON Schema | XSD, DTD |
| Features | Objects/arrays | Namespaces, attributes, XSLT |
| Web fit | Native | Less common now |
| Best for | Web APIs, config | Documents, enterprise, SOAP |
Use case and validation
JSON is the default for modern web and mobile APIs and most configuration. XML remains relevant for document-centric data, enterprise systems, SOAP services, and anywhere rich schema validation, namespaces, or XSLT transformations are needed. You consume XML when integrating legacy or document-heavy systems.
In CI
Validate JSON against JSON Schema and XML against XSD; run transformations in tests where used. Both run on managed runners, where faster runners shorten validation and transformation steps.
The verdict
Modern web APIs, mobile, and config: JSON, for simplicity and ubiquity. Document-centric data, enterprise integration, SOAP, or rich schema/namespace needs: XML. New systems default to JSON; XML endures in document and enterprise contexts.