validate-env-vars

A lightweight utility for checking the presence and validity of environment variables, as specified by a Zod schema.

validate-env-vars supports Zod v4 and Zod Mini!

Installation

Using npm:

npm install validate-env-vars --save-dev

Usage Examples

Create an executable JS file to check an .env file against a Zod schema:

#!/usr/bin/env node

import validateEnvVars from 'validate-env-vars';
import { z } from 'zod';

const envSchema = z.object({
	NODE_ENV: z.enum(['development', 'production', 'test']),
	API_BASE: z.url(),
	GITHUB_USERNAME: z.string().min(1),
});

validateEnvVars({ schema: envSchema });

---

Programmatically check an .env.production file against a Zod schema:

import validateEnvVars from 'validate-env-vars';
import { z } from 'zod';

const envSchema = z.object({
	NODE_ENV: z.enum(['development', 'production', 'test']),
	API_BASE: z.url(),
	GITHUB_USERNAME: z.string().min(1),
});

const preflight = () => {
	try {
		validateEnvVars({ schema: envSchema, envPath: '.env.production' });
		// ... other code
	} catch (error) {
		console.error(error);
		// ... other code
	}
};

---

Check env vars before Vite startup and build:

1. Define a Zod schema in a .ts file at the root of your project

import { z } from 'zod';

const envSchema = z.object({
	NODE_ENV: z.enum(['development', 'production', 'test']),
	VITE_API_BASE: z.url(),
	VITE_GITHUB_USERNAME: z.string().min(1),
});

// make the type of the environment variables available globally
declare global {
    type Env = z.infer<typeof envSchema>;
}

export default envSchema;

2. Import validateEnvVars and your schema and add a plugin to your Vite config to call validateEnvVars on buildStart

import { defineConfig } from 'vitest/config';
import envConfigSchema from './env.config';
import validateEnvVars from 'validate-env-vars';

export default defineConfig({
  plugins: [
    {
      name: 'validate-env-vars',
      buildStart: () => validateEnvVars({ schema: envConfigSchema }),
    },
    // other plugins...
  ],
  // other options...

3. Enable typehints and intellisense for the environment variables in your vite-env.d.ts

/// <reference types="vite/client" />

interface ImportMetaEnv extends globalThis.Env {}

interface ImportMeta {
	readonly env: ImportMetaEnv;
}

4. Add your schema configuration file to your tsconfig's include

Config Options

Option	Type	Description	Default
schema	EnvObject	The schema to validate against (must use string-based types)
envPath (optional)	string	The path to the .env file
exitOnError (optional)	boolean	Whether to exit the process or throw if validation fails	false
logVars (optional)	boolean	Whether to output successfully parsed variables to the console	true

Note: The schema must be a z.object() whose fields use string-based types—such as z.string(), z.enum(), z.literal(), or compositions like union/optional of these types. You may also use any Zod string refinements and formats (e.g., .min(), .max(), .url(), .email(), .regex(), .refine(), etc.) to validate and transform string values. Environment variables are always read as strings.

Schema Recipes

Since environment variables are always read as strings, you'll need to validate them appropriately. Here are some common patterns:

const envNonEmptyString = () =>
	z
		.string()
		.min(1, { message: 'Variable cannot be empty' })
		.refine((val) => val !== 'undefined', {
			message: "Variable cannot equal 'undefined'",
		});

// Integer from string (with stringFormat)
const envInteger = () =>
	z.stringFormat('int', (val) => z.int().safeParse(Number(val)).success);

// Integer from string (with refine)
const envIntegerRefine = () =>
	z.string().refine((val) => Number.isInteger(Number(val)), {
		message: 'Variable must be an integer',
	});

// Boolean from string
const envBoolean = () => z.enum(['true', 'false']);