diff --git a/corenetworks/client.py b/corenetworks/client.py
index 5b316ed..89775b6 100644
--- a/corenetworks/client.py
+++ b/corenetworks/client.py
@@ -3,6 +3,8 @@
 
 import copy
 import json
+import os
+from collections import defaultdict
 
 import jsonschema
 from requests import ConnectionError
@@ -23,12 +25,12 @@ from .exceptions import ValidationError
 class CoreNetworks():
     """Create authenticated API client."""
 
-    def __init__(self, user=None, password=None, api_token=None, auto_commit=False):
+    def __init__(self, user=None, password=None, api_token=None, auto_commit=None):
         self.__endpoint = "https://beta.api.core-networks.de"
         self.__user_agent = "Core Networks Python API {version}".format(
             version=corenetworks.__version__
         )
-        self.auto_commit = auto_commit
+        self.config = self._config(user, password, api_token, auto_commit)
 
         self._schema = {
             "type": "object",
@@ -94,14 +96,36 @@ class CoreNetworks():
             },
         }
 
-        if api_token:
+        if self.config["api_token"]:
             self._auth = CoreNetworksTokenAuth(api_token)
         else:
-            if not user or not password:
-                raise AuthError("Insufficient authentication details provided")
-
             self._auth = CoreNetworksBasicAuth(user, password, self.__endpoint)
 
+    @staticmethod
+    def _config(user, password, api_token, auto_commit):
+        cfg = defaultdict(
+            dict, {
+                "user": None,
+                "password": None,
+                "api_token": None,
+                "auto_commit": False
+            }
+        )
+
+        cfg["user"] = os.getenv("CN_API_USER")
+        cfg["password"] = os.getenv("CN_API_PASSWORD")
+        cfg["api_token"] = os.getenv("CN_API_TOKEN")
+
+        cfg["user"] = user or cfg["user"]
+        cfg["password"] = password or cfg["password"]
+        cfg["api_token"] = api_token or cfg["api_token"]
+        cfg["auto_commit"] = auto_commit or cfg["auto_commit"]
+
+        if not (cfg["user"] and cfg["password"]) and not cfg["api_token"]:
+            raise AuthError("Insufficient authentication details provided")
+
+        return cfg
+
     # ZONES
 
     def zones(self):
@@ -186,7 +210,7 @@ class CoreNetworks():
 
         result = self.records(zone=zone, params=params)
 
-        if self.auto_commit:
+        if self.config["auto_commit"]:
             self.commit(zone=zone)
 
         return self.__normalize(result)
@@ -224,7 +248,7 @@ class CoreNetworks():
             "/dnszones/{zone}/records/delete".format(zone=zone), data=params, method="POST"
         )
 
-        if self.auto_commit:
+        if self.config["auto_commit"]:
             self.commit(zone=zone)
 
         return self.__normalize(result)
diff --git a/corenetworks/test/unit/test_client.py b/corenetworks/test/unit/test_client.py
index b8d715b..a82fa86 100644
--- a/corenetworks/test/unit/test_client.py
+++ b/corenetworks/test/unit/test_client.py
@@ -23,7 +23,7 @@ def client(mocker):
     return client
 
 
-def test_auth_error():
+def test_auth_error(requests_mock):
     with pytest.raises(AuthError) as e:
         assert CoreNetworks(user="test")
     assert str(e.value) == "Insufficient authentication details provided"
@@ -135,7 +135,7 @@ def test_add_record(requests_mock, client, mocker):
     assert resp == [{"type": "A", "ttl": 1800, "name": "test", "data": "127.0.0.1"}]
 
     mocker.patch.object(client, "commit")
-    client.auto_commit = True
+    client.config["auto_commit"] = True
     client.add_record(zone="example.com", params=record)
     client.commit.assert_called_once_with(zone="example.com")
 
@@ -157,7 +157,7 @@ def test_delete_record(requests_mock, client, mocker):
     assert forced == []
 
     mocker.patch.object(client, "commit")
-    client.auto_commit = True
+    client.config["auto_commit"] = True
     client.delete_record(zone="example.com", params={
         "type": "A",
     })