Env File Parser

Example

This input uses made-up values and covers the cases the parser treats specially:

# Database config
DB_HOST=localhost
DB_PORT=5432 # default port
DB_PASSWORD="s3cr3t#1"
API_KEY=
APP_ENV=development
APP_ENV=production
export NODE_ENV=production
COLOR=#fff
PRIVATE_KEY="-----BEGIN KEY-----
abc
-----END KEY-----"
GREETING="Hello\nWorld"
SINGLE='Hello\nWorld'
my-key=1
BROKEN LINE

The table and notes it produces:

The status line reads “7 valid, 5 warnings, 1 error.” (rows 2, 6 and the others without notes count as valid). Export JSON then downloads env.json with 11 keys, the same object that dotenv 16.6.1’s dotenv.parse() returns for this text: APP_ENV is production, COLOR is an empty string, and the broken line is left out. The tool’s test suite compares its export with dotenv.parse() on this example and on a set of edge cases.

Colons, Spaces and Other Keys

dotenv also reads KEY: value, as in YAML, but only with a space after the colon. A line that dotenv skips is an error in the table and is left out of Export JSON; a key that dotenv accepts but that is unusual gets a warning and stays in the export:

DB_HOST: db.internal
export REDIS_URL: redis://cache:6379/0
MY KEY=1
my.key=2
PORT:8080

{
  "DB_HOST": "db.internal",
  "REDIS_URL": "redis://cache:6379/0",
  "my.key": "2"
}

The status line reads “2 valid, 1 warning, 2 errors.” Line 3 (MY KEY=1) shows Non-standard key name as an error because dotenv’s key pattern [\w.-]+ has no space. Line 5 shows Use KEY=value, or KEY: value with a space after the colon and none before it. Node.js has its own parser (—env-file, util.parseEnv()), and Node.js 22.23.3 reads this text differently: it keeps MY KEY and my.key and ignores all three colon lines.

A key named proto is the one place where the export differs from dotenv.parse(), which drops that key:

__proto__=keep
A=1

{
  "__proto__": "keep",
  "A": "1"
}

Limits

• No variable expansion. ${HOME}/data stays as written. dotenv-expand, Docker Compose and some frameworks expand such references, so the value your app sees can differ.
• dotenv rules only. Other loaders differ: Node.js —env-file (see above), Docker Compose’s env_file, Python’s python-dotenv and shell source treat quotes, colons, export and # in their own ways. Check the loader you actually use when a value contains quotes or #, or when a line uses a colon.
• Values are shown in clear text. The table does not mask secrets, so mind screen sharing; nothing is stored or sent. To share a file safely, replace the values with the secret redactor first.
• JSON only. There is no export to YAML, shell export lines or a Kubernetes Secret; the downloaded file is always named env.json.

Common .env Pitfalls Detected

• Missing = sign — the line has neither = nor a colon, so it cannot be parsed as a key-value pair.
• Colon without a space — PORT:8080 and PORT : 8080 are skipped by dotenv; write PORT=8080 or PORT: 8080.
• Empty value — the key exists but the value is blank; may cause runtime errors depending on your app.
• Duplicate key — the same key appears more than once; dotenv uses the last value, other loaders may not.
• Non-standard key name — keys should start with a letter or underscore and contain only letters, digits, and underscores. Keys with . or - or a leading digit still load in dotenv (warning); keys with a space or other characters do not (error).
• # in an unquoted value — dotenv starts a comment there, so COLOR=#fff is empty and URL=https://example.com/#top loses #top. Put the value in quotes. Rules: dotenv parsing rules.