vs
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JSON vs XML: which data format should you use?
A clear, practical comparison with a straight answer.
Use JSON for new APIs, configuration and anything you are designing today, it is smaller and easier to read and write. Keep XML where an existing system, feed format or schema already requires it.
Both formats describe structured data as plain text, but they read very differently. JSON uses braces, brackets and key-value pairs and maps directly onto the data structures of most programming languages. XML wraps everything in nested tags, closer to HTML.
JSON's compactness is why it took over most web APIs from XML over the last decade. XML has not disappeared, it still underpins RSS feeds, sitemaps and document formats like DOCX that were built around it.
.json vs .xml at a glance
| .json | .xml | |
|---|---|---|
| Syntax | Concise, key-value and arrays | Verbose, nested tags |
| Schema validation | Via JSON Schema (optional) | Built in (DTD, XSD) |
| Typical file size | Smaller | Larger |
| Human readability | Good | Good, but wordier |
| Where it remains standard | Web APIs, config files | RSS feeds, sitemaps, Office formats |
| Best for | Modern web APIs and config | Systems already built around XML |
Frequently asked questions
Why did JSON replace XML for most APIs?
JSON is shorter, easier to read and maps directly onto objects and arrays in most programming languages, which meant less code to parse it.
Is XML obsolete?
No. It still powers RSS feeds, sitemaps and document formats like DOCX and XLSX internally, and many enterprise systems still exchange XML.