.env Validator Online — Catch Missing Keys Free
Check a .env file for the failures that break deployments at 2am — missing required keys, silent duplicate overrides, malformed lines, and suspicious values — against your .env.example or a pasted key list.
- Paste your .env.example (or just a list of key names) as the reference to catch missing keys.
- Errors block deployment; warnings are heuristic (short secrets, non-numeric ports, missing URL schemes).
- Run it before every deploy — it takes two seconds and catches the wrong-environment mistake.
Your .env file is the most sensitive text in your repo — database passwords and signing keys included. Parsing, cleaning, and conversion all run in your browser. Nothing is uploaded, stored, or logged.
What gets flagged
Errors are structural: lines without KEY=value syntax, keys defined twice (most loaders silently keep the last), and keys present in your reference but missing here — the classic deploy-to-staging-with-production-env failure.
Warnings are judgment calls the parser can make mechanically: a PORT value that is not numeric, a *_URL without a scheme, a *_SECRET shorter than 16 characters, unquoted values containing spaces. Each warning names the key so you can decide.
A pre-deploy ritual
Keep a committed .env.example as the contract. Before deploying, paste the target environment's real .env and the example, and read the missing-keys section — it is a checklist of exactly what will be undefined at runtime. process.env.MISSING_KEY does not throw in Node; it silently returns undefined and the failure surfaces later, in production, as something else.
That is the whole argument for validating: env validation failures are quiet until they are expensive.
Private by construction
Validation runs entirely in your browser. The real values — secrets included — are never uploaded, stored, or logged.
Frequently asked questions
What counts as the reference format?
Either an .env.example-style document (any KEY=value lines, values usually empty) or a bare list of key names separated by commas, spaces, or newlines. The tool detects which one you pasted.
Why are duplicates an error when loaders allow them?
Because loaders resolve them silently — usually last-wins — and nobody reading the file can tell which line is live. One of the two definitions is a bug; the tool makes you look at it.
Are my env values uploaded during validation?
No. Parsing and checking happen locally in your browser. This page is safe to use with production secrets.