JSON vs YAML vs TOML: Configuration Formats Compared
Syntax differences, comments, data types, tooling and which format fits APIs, Kubernetes manifests and app config files.
JSON
Strict, typed by structure, universally parseable. No comments — which is why config formats grew up around it. The right wire format for APIs.
YAML
Indentation-based superset of JSON semantics with anchors, multi-line strings and comments. Great for humans, dangerous for machines: the Norway-problem (yes/no → booleans) and billion laughs expansion are real. Pin versions and validate on load.
TOML
INI-inspired, explicitly typed, designed for config files with least ambiguity. Kubernetes uses YAML, Rust ecosystems use TOML, most APIs stay on JSON. Convert freely with the data conversion tools.