JSON and XML are the two most prominent structured data formats in computing. While JSON dominates modern REST and GraphQL APIs, XML remains vital in enterprise systems, document publishing, and configuration.
| Feature | JSON | XML |
|---|---|---|
| Syntax | Concise, key-value pairs | Tag-based markup with closing tags |
| Data Types | Native strings, numbers, bools, arrays | Text only (types require schemas) |
| Comments | Not supported in standard JSON | Supported via <!-- --> |
| Attributes | No distinct attribute concept | Attributes inside tags (<user id="1">) |
| Metadata | Must be nested as fields | Supports namespaces and DTDs |
| Parsing Speed | Very fast, minimal memory | Slower, complex DOM tree building |
When to Choose Which?
Choose JSON when building web applications, microservices, mobile APIs, or browser-based data stores. Choose XML when you need document markup (HTML/SVG), legacy SOAP web services, complex schema validation, or hierarchical documents with mixed text and formatting.