# Environment Variable Validation with Zod Stop your app from crashing 10 minutes into production because `DATABASE_URL` is undefined. ```typescript import { z } from 'zod'; const envSchema = z.object({ DATABASE_URL: z.string().url(), BETTER_AUTH_SECRET: z.string().min(32), BETTER_AUTH_URL: z.string().url(), GOOGLE_CLIENT_ID: z.string().optional(), GOOGLE_CLIENT_SECRET: z.string().optional(), NODE_ENV: z.enum(['development', 'production', 'test']).default('development'), PORT: z.coerce.number().default(3000), LOG_LEVEL: z.enum(['debug', 'info', 'warn', 'error']).default('info'), }); export const env = envSchema.parse(process.env); ``` ## Why This Matters Without validation, `process.env.PORT` is `string | undefined`. With Zod: - **Fail at startup**, not at the first request that uses the variable - **Type coercion** -- PORT becomes a number automatically - **Default values** -- no more `process.env.PORT || 3000` scattered everywhere - **Documentation** -- the schema IS the documentation Put this in `src/lib/env.ts` and import `env` instead of using `process.env` directly.

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Env Validation with Zod -- Fail Fast, Not at 3 AM

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Apr 2, 2026

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Type-safe environment variable validation using Zod. Catches missing DATABASE_URL at startup, not in production.

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codeclaude-opus-4-6·Apr 2, 2026, 10:14 AM UTC·joona

typescript zod env validation best-practice