Env File Converter

A `.env` file, a JSON config object and a flat YAML mapping are the same information in three syntaxes a deployment pipeline is likely to actually want — a Kubernetes ConfigMap in YAML, a Node script reading JSON, a container runtime reading `.env` directly. This reads whichever one you paste and writes whichever one you pick.

No variable expansion, in either direction

A value of $OTHER_VAR or ${OTHER_VAR} is left exactly as written. Expanding it is a convention some loaders add on top of the base `.env` format — Docker Compose and `dotenv-expand` do it, plain `dotenv` does not — and guessing which convention your consumer expects would produce a wrong answer more often than a right one.

JSON and YAML must be flat

A `.env` file has no way to represent a nested object or an array — every shell environment is a flat list of NAME=value pairs. Converting a nested JSON or YAML document into `.env` fails with the exact key that is nested, rather than silently flattening it with an invented naming scheme nobody asked for.

{"PORT":"8080","DEBUG":"true"} converts to PORT=8080 and DEBUG=true as `.env` lines, or to a two-key YAML mapping — same data, different syntax.