tool4.dev

Data / LOCAL TOOL

.env.example to Typed Config Loader

Generate a validated TypeScript, Go, or Python configuration loader from .env.example.

Runs locally — input is never uploaded
Paste or drop a .env.example file
Ready when you are

WHAT IT DOES

Make the environment contract fail at startup, not halfway through a request.

Paste the .env.example that documents an application and generate a small typed loader for TypeScript, Go, or Python using only each runtime's standard facilities. Blank entries become required variables, populated entries become defaults, and demonstrated numbers and booleans receive parsing with explicit errors. Names that look like credentials never carry their example value into generated source, even if someone accidentally pasted a real secret instead of a placeholder.

Why use it?

Use it to turn documented environment settings into startup checks, so missing or wrongly typed configuration fails close to where it is loaded.

How to use this tool

  1. Paste a reviewed .env.example rather than production credentials, then choose the output language.
  2. Generate the loader and inspect the required variables, inferred types, and defaults. PORT=3000 demonstrates a numeric default; an empty variable becomes required.
  3. Integrate it into the application's startup path and test missing, empty, and malformed values. The generated loader reads the process environment; it does not install your deployment configuration.

Details and limitations

  • The generated loader distinguishes an unset variable from an empty required value and reports the exact environment name that failed validation.
  • TypeScript reads process.env, Go uses os.LookupEnv with strconv, and Python returns a frozen dataclass populated from os.environ.
  • Variables containing secret, password, token, private key, API key, or access key markers are always required and their pasted defaults are discarded.

WORKED EXAMPLES

Defaults for settings, no default for a credential

Generate the TypeScript loader from these dummy settings. PORT and DEBUG demonstrate numeric and boolean defaults; API_KEY deliberately demonstrates a sensitive-looking name.

Example environment

PORT=3000
DEBUG=false
API_KEY=DEMO_ONLY

Expected result

The loader parses PORT as a number and DEBUG as a boolean. API_KEY is required and DEMO_ONLY does not appear in the generated source. Review names with less obvious sensitivity yourself.

COMMON QUESTIONS

.env → Config questions

Should I paste a real production .env file?
Prefer the committable .env.example. The tool strips defaults from secret-like names, but a real environment file may contain sensitive values that do not use recognizable names.
How are required variables and types inferred?
Blank values are required. Safe populated values become defaults; true and false become booleans, numeric literals become numbers, and everything else remains a string.