python-dotenv
Loads environment variables from .env files into Python's os.environ. python-dotenv reads KEY=VALUE pairs from .env files and sets them in the process environment, enabling 12-factor app configuration without modifying system environment. A single load_dotenv() call at the top of the entry point populates all downstream os.getenv() calls. The standard way to manage local development environment variables in Python.
Score Breakdown
⚙ Agent Friendliness
🔒 Security
.env files with secrets must be in .gitignore — python-dotenv does not enforce this. Secrets in .env files are plaintext; not suitable for production. Use for local dev only.
⚡ Reliability
Best When
You need a simple way to manage local development environment variables without setting them in your shell or committing them to git.
Avoid When
You're in production — use a proper secrets manager. Or if you need type validation — use pydantic-settings which includes dotenv support.
Use Cases
- • Load agent API keys and database URLs from .env files during local development without exposing secrets in code or shell profiles
- • Switch between environment configurations (dev/test/prod) with different .env files passed to load_dotenv(dotenv_path='.')
- • Set default values for environment variables with dotenv_values() while allowing environment overrides for deployment
- • Use python-dotenv CLI to run commands with specific .env file variables without polluting the shell environment
- • Integrate with pydantic-settings which reads .env files automatically — python-dotenv handles the file reading layer
Not For
- • Production secret management — .env files are not suitable for production; use AWS Secrets Manager, Vault, or Kubernetes secrets
- • Complex configuration hierarchies — use pydantic-settings or dynaconf for validated, typed configuration with multiple sources
- • Runtime configuration updates — dotenv loads once at startup; use a dynamic config service for runtime changes
Interface
Authentication
Local library — no external auth. Reads local files.
Pricing
BSD-licensed open source Python package.
Agent Metadata
Known Gotchas
- ⚠ load_dotenv() must be called BEFORE importing code that reads os.environ — modules that read env vars at import time won't see dotenv values if dotenv is loaded after import
- ⚠ By default, load_dotenv() does NOT override existing environment variables — use override=True to force .env values to take precedence over system environment
- ⚠ load_dotenv() silently succeeds even if .env file doesn't exist — use find_dotenv(raise_error_if_not_found=True) for agent code that requires a .env file
- ⚠ .env files with multi-line values must wrap in double quotes with literal newlines — FORMAT: KEY='line1\nline2' causes \n to appear as literal characters, not newlines
- ⚠ Comments in .env files must start with # at the beginning of the line — inline comments (KEY=value # comment) are NOT supported and become part of the value in some dotenv implementations
- ⚠ python-dotenv reads .env from the current working directory by default — agent code with different working directories must explicitly pass dotenv_path to load_dotenv()
Alternatives
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Scores are editorial opinions as of 2026-03-06.