JSON vs. XML vs. YAML: Which Format Fits?

JSON, XML, and YAML can all carry structured data, but they express different things and have different parsing rules. Choose the format required by the receiving system first. Convert only after deciding how types, names, and nested values should map.

The same small record

JSON:

{ "name": "Alex", "active": true, "roles": ["author", "reviewer"] }

YAML:

name: Alex
active: true
roles:
  - author
  - reviewer

One possible XML representation:

<person active="true"><name>Alex</name><roles><role>author</role><role>reviewer</role></roles></person>

The XML example is a chosen mapping. XML has elements, attributes, and text, so there is no universal conversion between arbitrary JSON and XML. Another system might represent active as a child element and use a schema to assign its boolean meaning.

Practical differences

Format	Common use	Conversion issue
JSON	APIs and application data	No native comments or date type
YAML	Human-edited configuration	Aliases and complex keys can exceed JSON’s data model
XML	Document and schema-driven interchange	Attributes, namespaces, and mixed content need a mapping

The JSON to YAML and YAML to JSON tools handle their documented subset locally. The JSON to XML tool uses an explicit typed mapping so unusual JSON property names remain representable. It does not claim to produce another application’s XML schema.

Before replacing a format in a workflow, inspect a real sample and its consumer. Check whether comments, exact number spelling, XML attributes, or YAML aliases have meaning for that system. The JSON syntax guide covers the JSON side in more detail.