diff --git a/.gitignore b/.gitignore
index 64af339..0ea982e 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,6 +1,7 @@
 /.venv
 /samples
-/.env
+.env
+!.env.example
 __pycache__/
 venv/
 */__pycache__/
\ No newline at end of file
diff --git a/generic_loader/.env.example b/generic_loader/.env.example
index 5be8065..11161dc 100644
--- a/generic_loader/.env.example
+++ b/generic_loader/.env.example
@@ -3,3 +3,6 @@ PGPORT=5432
 PGUSER=
 PGPASSWORD=
 PGDATABASE=
+
+S3_BUCKET=my-bucket
+AWS_PROFILE=default
diff --git a/utils/data_explorer.py b/utils/data_explorer.py
index e2825c2..ec53ba0 100644
--- a/utils/data_explorer.py
+++ b/utils/data_explorer.py
@@ -35,6 +35,10 @@ import sys
 from dataclasses import dataclass, field
 from typing import List, Set, Tuple
 
+from dotenv import find_dotenv, load_dotenv
+
+load_dotenv(find_dotenv())
+
 # ---------------------------------------------------------------------------
 # Dependency check
 # ---------------------------------------------------------------------------
@@ -75,10 +79,10 @@ FILE_EXTENSIONS: Set[str] = SUPPORTED_EXTENSIONS
 INPUT_FILE: str = "s3_directories.txt"
 """Path to the text file containing one S3 prefix per line."""
 
-S3_BUCKET: str = "my-bucket"
+S3_BUCKET: str = os.environ.get("S3_BUCKET", "my-bucket")
 """S3 bucket name (all prefixes are assumed to live in this bucket)."""
 
-AWS_PROFILE: str = "default"
+AWS_PROFILE: str = os.environ.get("AWS_PROFILE", "default")
 """AWS CLI profile name used for authentication."""
 
 # Text-file reading defaults (used when downloading / previewing text files)
diff --git a/utils/file_viewer.py b/utils/file_viewer.py
index 6c6343d..85f42eb 100644
--- a/utils/file_viewer.py
+++ b/utils/file_viewer.py
@@ -21,6 +21,10 @@ import argparse
 import os
 import sys
 
+from dotenv import find_dotenv, load_dotenv
+
+load_dotenv(find_dotenv())
+
 import boto3
 import pandas as pd
 import pyreadstat
@@ -44,7 +48,7 @@ SUPPORTED_EXTENSIONS: set[str] = SAS_EXTENSIONS | TEXT_EXTENSIONS
 # Configuration — edit these before running (or use CLI arguments)
 # ---------------------------------------------------------------------------
 
-S3_BUCKET: str = "my-bucket"
+S3_BUCKET: str = os.environ.get("S3_BUCKET", "my-bucket")
 """S3 bucket name."""
 
 S3_KEY: str = "path/to/file.sas7bdat"
@@ -53,7 +57,7 @@ S3_KEY: str = "path/to/file.sas7bdat"
 LOCAL_FOLDER: str = "./downloads"
 """Local directory to download the file into."""
 
-AWS_PROFILE: str = "default"
+AWS_PROFILE: str = os.environ.get("AWS_PROFILE", "default")
 """AWS CLI profile name used for authentication."""
 
 
diff --git a/utils/s3_download.py b/utils/s3_download.py
index d1a2f2e..0cbb3b4 100644
--- a/utils/s3_download.py
+++ b/utils/s3_download.py
@@ -92,6 +92,7 @@ Exit codes:
 from __future__ import annotations
 
 import argparse
+import os
 import re
 import sys
 from concurrent.futures import ThreadPoolExecutor, as_completed
@@ -99,6 +100,10 @@ from dataclasses import dataclass, field
 from pathlib import Path
 from typing import Any, Dict, List, Optional, Tuple
 
+from dotenv import find_dotenv, load_dotenv
+
+load_dotenv(find_dotenv())
+
 import boto3
 import yaml
 
@@ -226,15 +231,20 @@ def load_download_config(path: Path) -> DownloadConfig:
             f"Config at {path} must be a YAML mapping at the top level."
         )
 
-    missing = [
-        k for k in ("bucket", "prefix", "local_folder") if k not in raw
-    ]
+    # 'bucket' can fall back to the S3_BUCKET env var, so only flag it as
+    # missing when neither the YAML key nor the env var is present.
+    required_always = ("prefix", "local_folder")
+    missing = [k for k in required_always if k not in raw]
+    if "bucket" not in raw and not os.environ.get("S3_BUCKET"):
+        missing.insert(0, "bucket")
     if missing:
         raise ValueError(
             f"Config {path} missing required keys: {', '.join(missing)}"
         )
 
-    bucket = str(raw["bucket"]).strip()
+    bucket = str(raw["bucket"]).strip() if raw.get("bucket") else ""
+    if not bucket:
+        bucket = os.environ.get("S3_BUCKET", "")
     if not bucket:
         raise ValueError(f"Config {path}: 'bucket' must be a non-empty string.")
 
@@ -256,6 +266,8 @@ def load_download_config(path: Path) -> DownloadConfig:
     aws_profile = raw.get("aws_profile")
     if aws_profile is not None:
         aws_profile = str(aws_profile).strip() or None
+    if aws_profile is None:
+        aws_profile = os.environ.get("AWS_PROFILE") or None
 
     auto_detect = bool(raw.get("auto_detect", True))
     extensions = _parse_extensions(raw.get("extensions"), f"Config {path}")