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.env File Validator

Check a .env file for syntax errors, duplicate keys, exposed secrets and missing entries.

A .env validator catches the mistakes that silently break configuration: duplicate keys where the last quietly wins, whitespace around the equals sign, unquoted values containing spaces or hash characters, and secrets given a NEXT_PUBLIC or VITE prefix that bundles them into client-side JavaScript.

Runs in your browser
Privacy
Values that look like credentials are masked in the output and never leave your browser
Cost
Free, unlimited, no sign-up

Frequently asked questions

Why is NEXT_PUBLIC_SECRET_KEY dangerous?

Any variable with that prefix is inlined into the JavaScript bundle sent to every visitor. It is not hidden, obfuscated or protected — it is published. If a key must stay secret, it can only be used server-side.

How to use the .env file validator

  1. 1Enter or paste your .env file.
  2. 2Enter or paste your .env.example (optional).
  3. 3The result appears immediately — copy or download it.

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Put the working .env file validator on your own site. It runs in your visitors' browsers exactly as it does here — free, no account, nothing uploaded.

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