diff --git a/README.md b/README.md
index 7fee0c8..a950e9c 100644
--- a/README.md
+++ b/README.md
@@ -212,8 +212,8 @@ ad_defaults:
   active: true
   type: # one of: OFFER, WANTED
   description:
-    prefix:
-    suffix:
+    prefix: ""
+    suffix: ""
   price_type: # one of: FIXED, NEGOTIABLE, GIVE_AWAY
   shipping_type: # one of: PICKUP, SHIPPING, NOT_APPLICABLE
   contact:
@@ -239,11 +239,12 @@ browser:
     # --headless
     # --start-maximized
   binary_location: # path to custom browser executable, if not specified will be looked up on PATH
+  extensions: [] # a list of .crx extension files to be loaded
 
 # login credentials
 login:
-  username:
-  password:
+  username: ""
+  password: ""
 
 ```
 
diff --git a/kleinanzeigen_bot/__init__.py b/kleinanzeigen_bot/__init__.py
index ba5cbdb..4b6251d 100644
--- a/kleinanzeigen_bot/__init__.py
+++ b/kleinanzeigen_bot/__init__.py
@@ -272,6 +272,7 @@ class KleinanzeigenBot(SeleniumMixin):
 
         self.browser_arguments = self.config["browser"]["arguments"]
         self.browser_binary_location = self.config["browser"]["binary_location"]
+        self.browser_extensions = [ abspath(item, relative_to = self.config_file_path) for item in self.config["browser"]["extensions"] ]
 
     def login(self) -> None:
         LOG.info("Logging in as [%s]...", self.config["login"]["username"])
diff --git a/kleinanzeigen_bot/resources/config_defaults.yaml b/kleinanzeigen_bot/resources/config_defaults.yaml
index bee4195..ab36d84 100644
--- a/kleinanzeigen_bot/resources/config_defaults.yaml
+++ b/kleinanzeigen_bot/resources/config_defaults.yaml
@@ -3,23 +3,27 @@ ad_files:
   - "**/ad_*.yml"
   - "**/ad_*.yaml"
 
+# default values for ads, can be overwritten in each ad configuration file
 ad_defaults:
   active: true
-  type: OFFER
+  type: OFFER # one of: OFFER, WANTED
   description:
     prefix: ""
     suffix: ""
-  price_type: NEGOTIABLE
-  shipping_type: SHIPPING
+  price_type: NEGOTIABLE # one of: FIXED, NEGOTIABLE, GIVE_AWAY
+  shipping_type: SHIPPING # one of: PICKUP, SHIPPING, NOT_APPLICABLE
   contact:
     name: ""
     street: ""
     zipcode:
     phone: "" # IMPORTANT: surround phone number with quotes to prevent removal of leading zeros
-  republication_interval: 7
+  republication_interval: 7 # every X days ads should be re-published
 
+# additional name to category ID mappings, see default list at
+# https://github.com/Second-Hand-Friends/kleinanzeigen-bot/blob/main/kleinanzeigen_bot/resources/categories.yaml
 categories: []
 
+# browser configuration
 browser:
   # https://peter.sh/experiments/chromium-command-line-switches/
   arguments:
@@ -28,8 +32,10 @@ browser:
     - --no-sandbox
     # --headless
     # --start-maximized
-  binary_location:
+  binary_location: # path to custom browser executable, if not specified will be looked up on PATH
+  extensions: [] # a list of .crx extension files to be loaded
 
+# login credentials
 login:
-  username: "" 
+  username: ""
   password: ""
diff --git a/kleinanzeigen_bot/selenium_mixin.py b/kleinanzeigen_bot/selenium_mixin.py
index c1fe99c..a18f6da 100644
--- a/kleinanzeigen_bot/selenium_mixin.py
+++ b/kleinanzeigen_bot/selenium_mixin.py
@@ -35,6 +35,7 @@ class SeleniumMixin:
     def __init__(self):
         self.browser_arguments:Iterable[str] = []
         self.browser_binary_location:str = None
+        self.browser_extensions:Iterable[str] = []
         self.webdriver:WebDriver = None
 
     def create_webdriver_session(self) -> None:
@@ -54,6 +55,11 @@ class SeleniumMixin:
                 browser_options.add_argument(chrome_option)
             LOG.debug("Effective browser arguments: %s", browser_options.arguments)
 
+            for crx_extension in self.browser_extensions:
+                ensure(os.path.exists(crx_extension), f"Configured extension-file [{crx_extension}] does not exist.")
+                browser_options.add_extension(crx_extension)
+            LOG.debug("Effective browser extensions: %s", browser_options.extensions)
+
             browser_options.add_experimental_option("excludeSwitches", ["enable-automation"])
             browser_options.add_experimental_option("useAutomationExtension", False)
             browser_options.add_experimental_option("prefs", {