Validate env vars without library

Short summary

Author built a minimal 60-line TypeScript function to validate environment variables without external dependencies, then discovered why that approach breaks down at scale. Production teams need libraries for CLI tooling, automatic documentation generation, framework adapters, consistent error messages, and secret masking. Pragmatic take: DIY and learn under 5 env vars; adopt a library like CtroEnv once your team adds CI/CD pipelines and staging/production deployments.

• •DIY env validation works for personal projects but lacks tooling as teams scale to production
• •Libraries provide CLI validation, docs generation, framework adapters (Next.js, Vite), consistent errors, and secret masking
• •Decision framework: under 5 vars? Build yourself and learn. Team or production? Use a library

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