{}JSON FYI

JSON vs YAML vs XML: which should you use?

A side-by-side comparison covering syntax, performance, tooling, and where each format shines.

·8 min read

All three encode structured data, but they make different trade-offs.

JSON

Strict, predictable, machine-first. Parsing is fast and behavior is consistent across languages. The downside: no comments, verbose for human-edited config.

YAML

Human-first. Indentation-based, supports comments and anchors. Great for config files. The downside: surprising parse rules ('yes' is a boolean, leading zero numbers are octal in YAML 1.1) and slower parsers.

XML

Verbose, schema-rich, attribute/element distinction. Still common in enterprise systems and document-oriented contexts (SVG, RSS). Heavy for typical API payloads.

When to choose what

  • API responses, browser ↔ server, configs the program writes: JSON
  • Configs humans edit by hand: YAML (or TOML)
  • Document-style markup or legacy enterprise interop: XML

Frequently asked questions

Is YAML a superset of JSON?+

YAML 1.2 is officially a superset, but in practice tools differ. Don't rely on it.

Which is fastest to parse?+

JSON, by a comfortable margin in nearly every language.

Related tools & guides

JSON to XML

Convert JSON into well-formed XML with attributes.

JSON to YAML

Convert JSON into idiomatic YAML 1.2.

JSON Schema Validator

Validate JSON data against a JSON Schema — powered by Ajv.