제로 의존성 TypeScript env 유효성 검사기를 구축했습니다.

Every Node.js developer has been burned by this at least once:

const port = parseInt(process.env.PORT); // NaN if PORT is missing
const db = process.env.DATABASE_URL;     // string | undefined — not safe!

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Your app starts fine locally, then crashes in production because someone forgot to set an env var. The error shows up 3 hours later, not at startup.

The solution

I built @harmand66/typesafe-env — a tiny, zero-dependency library that validates and types your environment variables at boot time.

import { createEnv } from '@harmand66/typesafe-env';

const env = createEnv({
  PORT:         { type: 'number',  default: 3000 },
  DATABASE_URL: { type: 'string',  required: true },
  DEBUG:        { type: 'boolean', default: false },
});

// ✅ TypeScript knows PORT is a number
env.PORT + 1     // 3001 — not "30001"
env.DATABASE_URL // string — guaranteed, never undefined

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If anything is missing or wrong, your app fails immediately at startup with a clear message:
All errors at once — no more fixing them one by one.

Why not Zod?

Zod is great but it’s 57kb and requires a lot of boilerplate for this specific use case. @harmand66/typesafe-env is zero dependencies and does one thing well.

Try it

npm install @harmand66/typesafe-env

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GitHub: https://github.com/giannielloemmanuele-lgtm/typesafe-env
npm: https://www.npmjs.com/package/@harmand66/typesafe-env

Would love any feedback or contributions! 🙏