dotenv-type-generator

Reads a .env file and auto-generates TypeScript ProcessEnv type declarations — zero config, zero annotations required.

Install

npm install -D dotenv-type-generator

Usage

# Generate env.d.ts from .env (default)
npx dotenv-type-generator

# Custom .env path
npx dotenv-type-generator .env.local

# Write to a custom output file
npx dotenv-type-generator .env --out src/types/env.d.ts

# Generate a Zod validation schema instead
npx dotenv-type-generator .env --zod --out src/env.ts

# Print to stdout
npx dotenv-type-generator .env --print

What it generates

Given a .env file:

# Database configuration
DATABASE_URL=postgresql://user:pass@localhost:5432/mydb
PORT=3000
JWT_SECRET=super-secret-key
[email protected]

It generates env.d.ts:

// Auto-generated by dotenv-type-generator. Do not edit manually.

declare namespace NodeJS {
  interface ProcessEnv {
    /** Database configuration */
    DATABASE_URL: string;
    PORT: string;
    JWT_SECRET: string;
    SUPPORT_EMAIL: string;
  }
}

Now process.env.DATABASE_URL is fully typed. Typos in variable names are caught at compile time.

Zod schema output

With --zod, generates a Zod validation schema that validates env vars at startup:

import { z } from 'zod';

export const envSchema = z.object({
  DATABASE_URL: z.string().url(),
  PORT: z.string(),
  JWT_SECRET: z.string(),
  SUPPORT_EMAIL: z.string().email(),
});

export type Env = z.infer<typeof envSchema>;

Auto-run on install

Add to your package.json to auto-generate on every install:

{
  "scripts": {
    "postinstall": "dotenv-type-generator"
  }
}

Use as a library

import { parseEnvFile, generateDeclaration, generateZodSchema } from 'dotenv-type-generator';
import { readFileSync } from 'fs';

const content = readFileSync('.env', 'utf8');
const entries = parseEnvFile(content);
const declaration = generateDeclaration(entries);

Options

| Flag | Description | |------|-------------| | --out <file> | Output file path | | --zod | Generate Zod schema instead of .d.ts | | --print | Print to stdout |