JSON vs XML — Which Format Should You Use?

The short answer

Use JSON for most modern APIs, web applications, and data exchange between services. Use XML when working with legacy enterprise systems, document formats, or when you need features JSON lacks: comments, namespaces, or schemas.

Side-by-side comparison

JSON: high readability, smaller files, no comments, no namespaces, natively parsed in JavaScript, faster parsing. XML: medium readability, larger files (verbose tags), supports comments and namespaces, supports schema validation (XSD), better for streaming large data.

When to choose JSON

Building a REST API, storing config for modern web apps, communicating between microservices, working with JavaScript or Python, NoSQL databases, when speed is a priority.

When to choose XML

Integrating with legacy enterprise systems (SOAP, EDI), working with document formats (DOCX, XLSX use XML internally), when you need in-file comments, robust schema validation, or XSLT transformations.

Converting between formats

Use the JSON to XML or XML to JSON converters. Automated conversion works well for simple structures but may need manual adjustment for complex nested data.

FAQ

Is JSON faster than XML? Typically yes — JSON files are smaller and faster to parse.

Which is better for config files? JSON is popular (package.json, tsconfig.json), but YAML is increasingly preferred for readability. XML is common in Java projects.