Supports .env, dotenv, and shell export formats
Ready to validate
Paste your .env content and click Validate// validate .env syntax and catch errors instantly
Validate .env file syntax instantly. Check for duplicate keys, malformed values, missing quotes, and invalid characters in environment variables.
Ready to validate
Paste your .env content and click ValidateCopy your environment file content and paste it into the input area on the left.
Hit the Validate button or press Ctrl+Enter to run the analysis instantly.
Browse errors, warnings, and info messages. Each issue includes the line number and a clear explanation.
The Environment Variable Validator checks your .env file for syntax errors, naming convention violations, and potential runtime issues before they cause bugs in production. All validation runs entirely in your browser — your secrets never leave your machine.
No. All validation runs entirely in your browser using JavaScript. Your environment variables — including secrets, passwords, and API keys — never leave your machine and are never transmitted anywhere.
Each line should follow KEY=VALUE format. Keys must start with a letter or underscore and contain only letters, numbers, underscores, or dots. Values with spaces should be wrapped in double quotes. Lines starting with # are treated as comments.
When a key is defined more than once, different tools and libraries may pick different values — leading to unpredictable behavior. Some loaders use the first occurrence, others the last. Duplicates are always a bug waiting to happen.
By strong convention, environment variables use UPPERCASE_SNAKE_CASE names. This is the POSIX standard and is expected by most frameworks (Node.js, PHP, Python, Ruby, etc.). The validator flags lowercase keys as warnings, not errors, since some tools do support them.
If a value starts with a quote character (" or ') but does not end with the same quote character, the validator flags it. This is a common typo that causes parsers to either fail or read incorrect values into your app.
Yes. Lines using the shell export KEY=VALUE syntax are fully supported. The export prefix is recognized and stripped before key validation runs.
An environment variable validator is a developer tool that analyzes the contents of a .env file and checks for syntax errors, naming convention violations, and common configuration mistakes. These files are a cornerstone of modern application development — they store database credentials, API keys, feature flags, and service URLs outside of your codebase, keeping secrets out of version control and making apps easy to configure across different environments.
Because .env files are plain text and parsed by third-party libraries, small typos or formatting mistakes can cause silent failures: a value might come through as undefined, a wrong password might be used in production, or an app might crash on startup with a cryptic error message. A validator catches these issues before they reach your runtime.
The .env format looks deceptively simple, but it has several edge cases that trip up even experienced developers:
KEY = VALUE may not be parsed correctly by all loaders. Some treat the spaces as part of the key or value.APP_NAME=My Application without quotes may cause the parser to read only My as the value.PORT=3000 # http port without quoting the value may cause the comment text to be included in the value by some parsers." and forgetting to close it can cause the parser to consume subsequent lines as part of the value.The widely accepted convention for environment variable names comes from the POSIX standard, which defines valid variable names as starting with a letter or underscore (_), followed by any combination of letters, digits, and underscores. In practice, the developer community also uses SCREAMING_SNAKE_CASE (all uppercase with underscores) as the standard naming style.
Using lowercase keys like db_host instead of DB_HOST will work with many loaders but may break others, and it makes .env files harder to scan visually. The validator flags lowercase keys as warnings to help you stay consistent without blocking valid configurations.
This tool processes your .env content line by line in the browser. For each non-empty, non-comment line it:
= separator=/^[A-Za-z_][A-Za-z0-9_.]*$/export prefix and strips it before validationResults are grouped into three severity levels: Errors (must fix — will cause runtime problems), Warnings (should fix — may cause issues in some environments), and Info (worth knowing — typically harmless).
Following consistent formatting in your .env files makes them easier to maintain, review, and share across teams:
UPPER_SNAKE_CASE for key names\n, \t), and single quotes for literal strings# Database, # Redis).env to your .gitignore.env.example file with all required keys but no real values, committed to the repo as documentationThe .env format originated in the Ruby/Rails community but has been adopted across virtually every language and framework. In Node.js, the dotenv package is the de facto standard loader. Python projects use python-dotenv or django-environ. PHP applications often use vlucas/phpdotenv. In containerized environments, Docker and Docker Compose support .env files natively for injecting variables into services. Kubernetes uses ConfigMaps and Secrets for the same purpose at scale.
Despite this broad adoption, each loader has slightly different parsing behavior — especially around quoted values, multiline strings, and comments. Keeping your .env files clean and following the most conservative syntax rules ensures compatibility across all tools in your stack.
Environment variables are the standard mechanism for injecting secrets into applications, but they come with security responsibilities. Always treat .env files as sensitive — set restrictive file permissions (chmod 600 .env), never log or display environment variable values in production, and rotate secrets regularly. For production workloads, consider using a dedicated secrets manager (AWS Secrets Manager, HashiCorp Vault, Doppler) instead of static .env files, which provides audit trails, versioning, and fine-grained access control.