diff --git a/alertify.py b/alertify.py
index 6cb03b5..4506891 100644
--- a/alertify.py
+++ b/alertify.py
@@ -12,7 +12,7 @@ from src import Alertify
 
 if __name__ == '__main__':
 
-    def parse_cli():
+    def parse_cli() -> argparse.ArgumentParser:
         """
         Function to parse the CLI
         """
@@ -45,9 +45,9 @@ if __name__ == '__main__':
 
         return parser.parse_args()
 
-    def main():
+    def main() -> int:
         """
-        main()
+        Main program logic
         """
         logging.basicConfig(
             format='%(levelname)s: %(message)s',
@@ -69,7 +69,6 @@ if __name__ == '__main__':
         # -----------------------------
 
         if args.healthcheck:
-            # Invert the sense of 'healthy' for Unix CLI usage
             _, status = alertify.healthcheck()
             return status == 200
 
diff --git a/src/Alertify/__init__.py b/src/Alertify/__init__.py
index 66c8363..1404da3 100644
--- a/src/Alertify/__init__.py
+++ b/src/Alertify/__init__.py
@@ -11,6 +11,7 @@ __version__ = '2.0'
 
 import json
 import logging
+from typing import Optional, Tuple
 
 import werkzeug.exceptions
 from flask import Flask, request, request_started
@@ -39,7 +40,7 @@ class Alertify(FlaskView):
         # Instantiate with defaults
         self.configure()
 
-    def configure(self, configfile=None):
+    def configure(self, configfile: Optional[str] = None):
         """
         Configure from a configfile
         """
@@ -71,7 +72,7 @@ class Alertify(FlaskView):
         webapp.run(host='0.0.0.0', port=self.config.listen_port)
 
     @route('/alert', methods=['POST'])
-    def alert(self):
+    def alert(self) -> Tuple[str, int]:
         """
         Handle the alerts from Alertmanager
         """
@@ -89,7 +90,7 @@ class Alertify(FlaskView):
         except UnboundLocalError:
             return '', 204
 
-    def healthcheck(self):
+    def healthcheck(self) -> Tuple[str, int]:
         """
         Perform a healthcheck and return the results
         """
diff --git a/src/Alertify/config.py b/src/Alertify/config.py
index e4fbf1c..e5269da 100644
--- a/src/Alertify/config.py
+++ b/src/Alertify/config.py
@@ -5,6 +5,7 @@ import inspect
 import logging
 import os
 from distutils.util import strtobool
+from typing import Optional
 
 import yaml
 
@@ -23,7 +24,7 @@ class Config:
     listen_port = int(8080)
     verbose = int(0)
 
-    def __init__(self, configfile=None):
+    def __init__(self, configfile: Optional[str] = None):
         """
         Method to parse a configuration file
         """
@@ -50,14 +51,14 @@ class Config:
             else:
                 setattr(self, key, type(default_val)(userval))
 
-    def items(self):
+    def items(self) -> list:
         """
         Method to return an iterator for the configured items
         """
         return {key: getattr(self, key) for key in self.__dict__}.items()
 
     @classmethod
-    def keys(cls):
+    def keys(cls) -> list:
         """
         Method to return the defaults as a list of dict_keys
         """
@@ -74,7 +75,7 @@ class Config:
         ]
 
     @classmethod
-    def defaults(cls):
+    def defaults(cls) -> dict:
         """
         Classmethod to return the defaults as a dictionary
         """
diff --git a/src/Alertify/gotify.py b/src/Alertify/gotify.py
index 794de71..f1aac5b 100644
--- a/src/Alertify/gotify.py
+++ b/src/Alertify/gotify.py
@@ -5,6 +5,7 @@ import http.client
 import json
 import logging
 import socket
+from typing import Optional
 
 
 class Gotify:
@@ -12,7 +13,7 @@ class Gotify:
     Class to handle Gotify communications
     """
 
-    def __init__(self, server, port, app_key, client_key=None):
+    def __init__(self, server: str, port: int, app_key: str, client_key: Optional[str] = None):
         self.api = http.client.HTTPConnection(server, port)
         self.app_key = app_key
         self.client_key = client_key
@@ -21,7 +22,7 @@ class Gotify:
             'Accept': 'application/json',
         }
 
-    def _call(self, method, url, body=None):
+    def _call(self, method: str, url: str, body: Optional[str] = None) -> dict:
         """
         Method to call Gotify with an app or client key as appropriate
         """
@@ -60,14 +61,14 @@ class Gotify:
 
         return resp_obj
 
-    def delete(self, msg_id):
+    def delete(self, msg_id: str) -> dict:
         """
         Method to delete a message from the Gotify server
         """
         logging.debug('Deleting message ID: %s', msg_id)
         return self._call('DELETE', f'/message/{msg_id}')
 
-    def find_byfingerprint(self, message):
+    def find_byfingerprint(self, message: str) -> list:
         """
         Method to return the ID of a matching message
         """
@@ -75,7 +76,7 @@ class Gotify:
             new_fingerprint = message['fingerprint']
         except KeyError:
             logging.debug('No fingerprint found in new message')
-            return None
+            return list()
 
         msg_list = []
         for old_message in self.messages():
@@ -91,7 +92,7 @@ class Gotify:
 
         return msg_list
 
-    def messages(self):
+    def messages(self) -> dict:
         """
         Method to return a list of messages from the Gotify server
         """
@@ -103,14 +104,14 @@ class Gotify:
         logging.debug('Fetching existing messages from Gotify')
         return self._call('GET', '/message')['json'].get('messages', [])
 
-    def send_alert(self, payload):
+    def send_alert(self, payload: dict) -> dict:
         """
         Method to send a message payload to a Gotify server
         """
         logging.debug('Sending message to Gotify')
         return self._call('POST', '/message', body=json.dumps(payload, indent=2))
 
-    def healthcheck(self):
+    def healthcheck(self) -> dict:
         """
         Method to perform a healthcheck against Gotify
         """
diff --git a/src/Alertify/health.py b/src/Alertify/health.py
index f96abb1..40121fb 100644
--- a/src/Alertify/health.py
+++ b/src/Alertify/health.py
@@ -1,6 +1,9 @@
 """
 Module for handling any healthcheck related activity
 """
+from typing import Tuple
+
+from .gotify import Gotify
 
 
 class Healthcheck:
@@ -8,10 +11,10 @@ class Healthcheck:
     Class to handle the healthchecks
     """
 
-    def __init__(self, gotify_client):
+    def __init__(self, gotify_client: Gotify):
         self.gotify = gotify_client
 
-    def gotify_alive(self):
+    def gotify_alive(self) -> Tuple[str, int]:
         """
         Simple method to return the Gotify healthcheck response
         """
diff --git a/src/Alertify/messaging.py b/src/Alertify/messaging.py
index 993f39f..6a543ee 100644
--- a/src/Alertify/messaging.py
+++ b/src/Alertify/messaging.py
@@ -2,6 +2,9 @@
 Module for handling the messaging
 """
 import logging
+from typing import Optional
+
+from .gotify import Gotify
 
 
 class MessageHandler:
@@ -9,12 +12,17 @@ class MessageHandler:
     Class to handle alert messaging
     """
 
-    def __init__(self, gotify_client, disable_resolved=False, delete_onresolve=False):
+    def __init__(
+        self,
+        gotify_client: Gotify,
+        disable_resolved: Optional[bool] = False,
+        delete_onresolve: Optional[bool] = False,
+    ):
         self.gotify = gotify_client
         self.disable_resolved = disable_resolved
         self.delete_onresolve = delete_onresolve
 
-    def process(self, alert):
+    def process(self, alert: dict) -> dict:
         """
         Method to process the alert message
         """