diff --git a/README.md b/README.md
index 99bbdca..b19c888 100644
--- a/README.md
+++ b/README.md
@@ -38,7 +38,7 @@ Below are the available options for the configuration file.
 - nvdCveChApi: NVD CVE Change History API Endpoint
 - nvdCpeApi: NVD CPE API Endpoint
 - nvdCpeMcApi: NVD CPE Match Criteria API
-- apiKey: NVD API Key
+- apiKey: NVD API Key as string OR fetch from environment variable by setting to {"env": <NAME_OF_ENVIRONMENT_VAR>}
 - mongoHost: MongoDB Docker Container Hostname
 - mongoPort: MongoDB Docker Container Port
 - connRetries: Connection Retry Limit
diff --git a/maintain.py b/maintain.py
index eea2f7b..3a78c8d 100644
--- a/maintain.py
+++ b/maintain.py
@@ -113,7 +113,7 @@ def update_collection(coll: str, now: Datetime, **kwargs) -> None:
     metadata = vault_mongo.meta.find_one({"collection": coll})
     if not metadata or not (last_updated := metadata.get("updated")):
         raise MetadataNotFoundException(f"No {coll} metadata found")
-    results = [
+    results: list[ReplaceOne] = [
         ReplaceOne({"_id": x["_id"]}, x, upsert=True)
         for x in api_call(
             last_mod_start_date=last_updated.isoformat(),
@@ -182,7 +182,10 @@ def update_metadata(collection: str, datetime: Datetime) -> None:
                              help="purges selected collection before performing operation. "
                                   "Only functional for fetch operations.")
     args, api_options = arg_parse.parse_known_args()
-    api_options = {api_options[i][2:]: api_options[i + 1] for i in range(0, len(api_options), 2)}
+    api_options: dict[str, str] = {
+        api_options[i][2:]: api_options[i + 1]
+        for i in range(0, len(api_options), 2)
+    }
 
     vault_mongo, nvd_api, arg_to_print_and_func = setup(args.config)
 
diff --git a/vaultlib/config.py b/vaultlib/config.py
index eae41ea..91e9ec1 100644
--- a/vaultlib/config.py
+++ b/vaultlib/config.py
@@ -2,6 +2,7 @@
 This is used to configure VulnVault based on a configuration file.
 """
 from json import load
+from os import getenv
 from pathlib import Path
 
 from .utils import camel_to_snake
@@ -37,11 +38,11 @@ def __init__(self, config_path: str = "config.json") -> None:
         # Number of threads used to fetch API data
         self.fetch_threads: int = 3
         # NLTK "Punkt" Pre-trained model URL
-        self.punkt_url = "punkt"
+        self.punkt_url: str = "punkt"
 
         # All Config values from config.json are converted from camelCase to snake_case
         # overrides instance variable if exists
-        if (config_path := Path(config_path)).exists():
+        if (config_path := Path(config_path)).exists():  # type: ignore
             g_vars = dir(self)
             with open(config_path, "r", encoding="utf-8") as config_file:
                 for config_key, config_value in load(config_file).items():
@@ -49,7 +50,14 @@ def __init__(self, config_path: str = "config.json") -> None:
                     if config_key not in g_vars:
                         continue
 
-                    if (g_var_type := type(getattr(self, config_key))) is not str:
+                    if config_key == "api_key" and isinstance(config_value, dict):
+                        try:
+                            self.api_key = getenv(config_value["env"])  # type: ignore
+                        except KeyError as e:
+                            raise ValueError(
+                                "api_key JSON object does not have a \"env\" property"
+                            ) from e
+                    elif (g_var_type := type(getattr(self, config_key))) is not str:
                         setattr(self, config_key, g_var_type(config_value))
                     else:
                         setattr(self, config_key, config_value)