Technically YAML is a superset (or subset?) of JSON. https://yaml.org/spec/1.2-old/spec.html#id2759572 https://yaml.org/spec/1.2-old/spec.html#id2759572 Howev

Technically YAML is a superset (or subset?) of JSON. https://yaml.org/spec/1.2-old/spec.html#id2759572 https://yaml.org/spec/1.2-old/spec.html#id2759572 However, I find the toml language somehow the better tech, while I still think that configuration should not be a "format" but a language. I think at least the recomposition of values with other values should be possible: CONFIG_PATH="$MAIN_PATH/config" And why would you configure: DEV_PATH="dev" PRD_PATH="prod" when you could do MAIN_PATH=env.IS_PROD ? "prod" : "dev"