About .env Validator

Validate .env files and flag missing values or duplicate keys. Part of the DevTools Surf developer suite. Browse more tools in the Text / String collection.

Use Cases

• Validating environment files before deploying to production
• Checking for missing variables when onboarding new developers
• Auditing .env files for duplicate or conflicting key definitions
• Verifying .env.example completeness against actual .env files

Tips

• Paste your .env file to instantly find missing values
• Catch duplicate keys that may cause silent configuration bugs
• Validate formatting to ensure no spaces around equal signs

Fun Facts

• The dotenv pattern was popularized by the Ruby gem 'dotenv' created by Brandon Keepers in 2012.
• The Twelve-Factor App methodology, published by Heroku co-founder Adam Wiggins in 2011, established environment variables as the standard for configuration.
• A 2023 GitGuardian report found that over 10 million secrets were exposed in public GitHub repositories that year alone.

FAQ

What does validation catch?

Missing values (KEY= with no value), duplicate keys (last-wins in most loaders, which silently shadows), malformed lines (no =), and unmatched quotes.

Does it support .env schema like dotenv-safe?

Yes — paste a schema (required keys, one per line) and the validator reports which are missing. Useful for onboarding checks and CI validation.

Are comments preserved?

The validator ignores comments entirely. For comment-aware tooling, use a dotenv library in your build step.

What about variable interpolation (${OTHER_KEY})?

Detected but not resolved — the validator flags undefined references and reports them. The resolution rules differ per dotenv implementation.