env-validator-zero

Zero-dependency environment variable validator with full TypeScript support for Node.js, React, and Vite.

Features

• Zero dependencies - Lightweight and secure
• TypeScript inference - Full autocomplete and type safety
• Universal - Works with Node.js, Vite, and React
• Clear errors - Descriptive validation messages

Installation

npm install env-validator-zero

Usage

import { defineEnv, ENV } from 'env-validator-zero';

export const env = defineEnv({
  API_URL: ENV.string(),
  PORT: ENV.number().default(3000),
  DEBUG: ENV.boolean().optional(),
});

// Fully typed
console.log(env.API_URL);  // string
console.log(env.PORT);     // number
console.log(env.DEBUG);    // boolean | undefined

Schema Builders

ENV.string() - String values

• .optional() - Makes variable optional
• .default(value) - Provides fallback value

ENV.number() - Numeric values (parses strings automatically)

• .optional() - Makes variable optional
• .default(value) - Provides fallback value

ENV.boolean() - Boolean values (accepts: "true", "false", "1", "0")

• .optional() - Makes variable optional
• .default(value) - Provides fallback value

Error Handling

import { defineEnv, ENV, EnvValidationError } from 'env-validator-zero';

try {
  const env = defineEnv({
    API_KEY: ENV.string(),
  });
} catch (error) {
  if (error instanceof EnvValidationError) {
    console.error(error.message);
    process.exit(1);
  }
}

Error messages:

• Missing variables: Missing required environment variable: API_KEY
• Invalid types: Invalid number for PORT: expected number, got "abc"
• Multiple errors: Lists all validation failures

Examples

Node.js

import { defineEnv, ENV } from 'env-validator-zero';

export const env = defineEnv({
  NODE_ENV: ENV.string().default('development'),
  DATABASE_URL: ENV.string(),
  PORT: ENV.number().default(3000),
  ENABLE_LOGGING: ENV.boolean().default(true),
});

Vite/React

import { defineEnv, ENV } from 'env-validator-zero';

export const env = defineEnv({
  VITE_API_URL: ENV.string(),
  VITE_APP_TITLE: ENV.string().default('My App'),
  VITE_ENABLE_ANALYTICS: ENV.boolean().default(false),
});

Next.js

import { defineEnv, ENV } from 'env-validator-zero';

export const env = defineEnv({
  NEXT_PUBLIC_API_URL: ENV.string(),
  DATABASE_URL: ENV.string(),
  JWT_SECRET: ENV.string(),
});

License

MIT 2025