diff --git a/examples/basic_generation.py b/examples/basic_generation.py
index 844513d..6c973b9 100644
--- a/examples/basic_generation.py
+++ b/examples/basic_generation.py
@@ -9,7 +9,7 @@ import asyncio
 import edge_tts
 
 
-async def main():
+async def main() -> None:
     TEXT = "Hello World!"
     VOICE = "en-GB-SoniaNeural"
     OUTPUT_FILE = "test.mp3"
diff --git a/examples/dynamic_voice_selection.py b/examples/dynamic_voice_selection.py
index 844e51d..e7e67fb 100644
--- a/examples/dynamic_voice_selection.py
+++ b/examples/dynamic_voice_selection.py
@@ -11,7 +11,7 @@ import edge_tts
 from edge_tts import VoicesManager
 
 
-async def main():
+async def main() -> None:
     voices = await VoicesManager.create()
     voice = voices.find(Gender="Male", Language="es")
     # Also supports Locales
diff --git a/lint.sh b/lint.sh
index b80309d..6532c9b 100755
--- a/lint.sh
+++ b/lint.sh
@@ -1,3 +1,4 @@
 find src examples -name '*.py' | xargs black
 find src examples -name '*.py' | xargs isort
 find src examples -name '*.py' | xargs pylint
+find src examples -name '*.py' | xargs mypy
diff --git a/mypy.ini b/mypy.ini
new file mode 100644
index 0000000..c06d521
--- /dev/null
+++ b/mypy.ini
@@ -0,0 +1,13 @@
+[mypy]
+warn_return_any = True
+warn_unused_configs = True
+
+#disallow_any_unimported = True
+#disallow_any_expr = True
+#disallow_any_decorated = True
+#disallow_any_explicit = True
+#disallow_any_generics = True
+#disallow_subclassing_any = True
+#disallow_untyped_calls = True
+disallow_untyped_defs = True
+disallow_incomplete_defs = True
diff --git a/setup.cfg b/setup.cfg
index 8e8cd4f..1bf386e 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -27,4 +27,11 @@ where=src
 [options.entry_points]
 console_scripts =
     edge-tts = edge_tts.__main__:main
-    edge-playback = edge_playback.__init__:main
+    edge-playback = edge_playback.__main__:main
+
+[options.extras_require]
+dev =
+    black
+    isort
+    mypy
+    pylint
diff --git a/src/edge_playback/__init__.py b/src/edge_playback/__init__.py
deleted file mode 100644
index 863e4d0..0000000
--- a/src/edge_playback/__init__.py
+++ /dev/null
@@ -1,63 +0,0 @@
-#!/usr/bin/env python3
-
-"""
-Playback TTS with subtitles using edge-tts and mpv.
-"""
-
-import os
-import subprocess
-import sys
-import tempfile
-from shutil import which
-
-
-def main():
-    depcheck_failed = False
-    if not which("mpv"):
-        print("mpv is not installed.", file=sys.stderr)
-        depcheck_failed = True
-    if not which("edge-tts"):
-        print("edge-tts is not installed.", file=sys.stderr)
-        depcheck_failed = True
-    if depcheck_failed:
-        print("Please install the missing dependencies.", file=sys.stderr)
-        sys.exit(1)
-
-    media = None
-    subtitle = None
-    try:
-        media = tempfile.NamedTemporaryFile(delete=False)
-        media.close()
-
-        subtitle = tempfile.NamedTemporaryFile(delete=False)
-        subtitle.close()
-
-        print(f"Media file: {media.name}")
-        print(f"Subtitle file: {subtitle.name}\n")
-        with subprocess.Popen(
-            [
-                "edge-tts",
-                f"--write-media={media.name}",
-                f"--write-subtitles={subtitle.name}",
-            ]
-            + sys.argv[1:]
-        ) as process:
-            process.communicate()
-
-        with subprocess.Popen(
-            [
-                "mpv",
-                f"--sub-file={subtitle.name}",
-                media.name,
-            ]
-        ) as process:
-            process.communicate()
-    finally:
-        if media is not None:
-            os.unlink(media.name)
-        if subtitle is not None:
-            os.unlink(subtitle.name)
-
-
-if __name__ == "__main__":
-    main()
diff --git a/src/edge_playback/__main__.py b/src/edge_playback/__main__.py
index 2ac8c12..027e892 100644
--- a/src/edge_playback/__main__.py
+++ b/src/edge_playback/__main__.py
@@ -1,10 +1,63 @@
 #!/usr/bin/env python3
 
 """
-This is the main file for the edge_playback package.
+Playback TTS with subtitles using edge-tts and mpv.
 """
 
-from edge_playback.__init__ import main
+import os
+import subprocess
+import sys
+import tempfile
+from shutil import which
+
+
+def main() -> None:
+    depcheck_failed = False
+    if not which("mpv"):
+        print("mpv is not installed.", file=sys.stderr)
+        depcheck_failed = True
+    if not which("edge-tts"):
+        print("edge-tts is not installed.", file=sys.stderr)
+        depcheck_failed = True
+    if depcheck_failed:
+        print("Please install the missing dependencies.", file=sys.stderr)
+        sys.exit(1)
+
+    media = None
+    subtitle = None
+    try:
+        media = tempfile.NamedTemporaryFile(delete=False)
+        media.close()
+
+        subtitle = tempfile.NamedTemporaryFile(delete=False)
+        subtitle.close()
+
+        print(f"Media file: {media.name}")
+        print(f"Subtitle file: {subtitle.name}\n")
+        with subprocess.Popen(
+            [
+                "edge-tts",
+                f"--write-media={media.name}",
+                f"--write-subtitles={subtitle.name}",
+            ]
+            + sys.argv[1:]
+        ) as process:
+            process.communicate()
+
+        with subprocess.Popen(
+            [
+                "mpv",
+                f"--sub-file={subtitle.name}",
+                media.name,
+            ]
+        ) as process:
+            process.communicate()
+    finally:
+        if media is not None:
+            os.unlink(media.name)
+        if subtitle is not None:
+            os.unlink(subtitle.name)
+
 
 if __name__ == "__main__":
     main()
diff --git a/src/edge_playback/py.typed b/src/edge_playback/py.typed
new file mode 100644
index 0000000..e69de29
diff --git a/src/edge_tts/communicate.py b/src/edge_tts/communicate.py
index 0f416e0..29bbb9a 100644
--- a/src/edge_tts/communicate.py
+++ b/src/edge_tts/communicate.py
@@ -7,7 +7,7 @@ import json
 import re
 import time
 import uuid
-from typing import Dict, Generator, List, Optional
+from typing import Any, AsyncGenerator, Dict, Generator, List, Optional
 from xml.sax.saxutils import escape
 
 import aiohttp
@@ -96,7 +96,7 @@ def iter_bytes(my_bytes: bytes) -> Generator[bytes, None, None]:
         yield my_bytes[i : i + 1]
 
 
-def split_text_by_byte_length(text: bytes, byte_length: int) -> List[bytes]:
+def split_text_by_byte_length(text: str | bytes, byte_length: int) -> List[bytes]:
     """
     Splits a string into a list of strings of a given byte length
     while attempting to keep words together.
@@ -151,7 +151,7 @@ def mkssml(text: str | bytes, voice: str, pitch: str, rate: str, volume: str) ->
     return ssml
 
 
-def date_to_string():
+def date_to_string() -> str:
     """
     Return Javascript-style date string.
 
@@ -193,7 +193,7 @@ class Communicate:
 
     def __init__(
         self,
-        text: str | List[str],
+        text: str,
         voice: str = "Microsoft Server Speech Text to Speech Voice (en-US, AriaNeural)",
         *,
         pitch: str = "+0Hz",
@@ -207,9 +207,9 @@ class Communicate:
         Raises:
             ValueError: If the voice is not valid.
         """
-        self.text = text
-        self.codec = "audio-24khz-48kbitrate-mono-mp3"
-        self.voice = voice
+        self.text: str = text
+        self.codec: str = "audio-24khz-48kbitrate-mono-mp3"
+        self.voice: str = voice
         # Possible values for voice are:
         # - Microsoft Server Speech Text to Speech Voice (cy-GB, NiaNeural)
         # - cy-GB-NiaNeural
@@ -232,19 +232,19 @@ class Communicate:
 
         if re.match(r"^[+-]\d+Hz$", pitch) is None:
             raise ValueError(f"Invalid pitch '{pitch}'.")
-        self.pitch = pitch
+        self.pitch: str = pitch
 
         if re.match(r"^[+-]0*([0-9]|([1-9][0-9])|100)%$", rate) is None:
             raise ValueError(f"Invalid rate '{rate}'.")
-        self.rate = rate
+        self.rate: str = rate
 
         if re.match(r"^[+-]0*([0-9]|([1-9][0-9])|100)%$", volume) is None:
             raise ValueError(f"Invalid volume '{volume}'.")
-        self.volume = volume
+        self.volume: str = volume
 
-        self.proxy = proxy
+        self.proxy: Optional[str] = proxy
 
-    async def stream(self):
+    async def stream(self) -> AsyncGenerator[Dict[str, Any], None]:
         """Streams audio and metadata from the service."""
 
         websocket_max_size = 2**16
@@ -403,7 +403,7 @@ class Communicate:
 
     async def save(
         self, audio_fname: str | bytes, metadata_fname: Optional[str | bytes] = None
-    ):
+    ) -> None:
         """
         Save the audio and metadata to the specified files.
         """
diff --git a/src/edge_tts/list_voices.py b/src/edge_tts/list_voices.py
index 6e41d96..2f18cc4 100644
--- a/src/edge_tts/list_voices.py
+++ b/src/edge_tts/list_voices.py
@@ -3,13 +3,14 @@ list_voices package for edge_tts.
 """
 
 import json
+from typing import Any, Optional
 
 import aiohttp
 
 from .constants import VOICE_LIST
 
 
-async def list_voices(*, proxy=None):
+async def list_voices(*, proxy: Optional[str] = None) -> Any:
     """
     List all available voices and their attributes.
 
@@ -47,7 +48,7 @@ class VoicesManager:
     """
 
     @classmethod
-    async def create(cls):
+    async def create(cls): # type: ignore
         """
         Creates a VoicesManager object and populates it with all available voices.
         """
@@ -59,12 +60,12 @@ class VoicesManager:
         ]
         return self
 
-    def find(self, **kwargs):
+    def find(self, **kwargs: Any) -> list[dict[str, Any]]:
         """
         Finds all matching voices based on the provided attributes.
         """
 
         matching_voices = [
-            voice for voice in self.voices if kwargs.items() <= voice.items()
+            voice for voice in self.voices if kwargs.items() <= voice.items() # type: ignore
         ]
         return matching_voices
diff --git a/src/edge_tts/submaker.py b/src/edge_tts/submaker.py
index 5a432c3..373ca96 100644
--- a/src/edge_tts/submaker.py
+++ b/src/edge_tts/submaker.py
@@ -6,10 +6,11 @@ information provided by the service easier.
 """
 
 import math
+from typing import List, Tuple
 from xml.sax.saxutils import escape, unescape
 
 
-def formatter(offset1, offset2, subdata):
+def formatter(offset1: float, offset2: float, subdata: str) -> str:
     """
     formatter returns the timecode and the text of the subtitle.
     """
@@ -19,7 +20,7 @@ def formatter(offset1, offset2, subdata):
     )
 
 
-def mktimestamp(time_unit):
+def mktimestamp(time_unit: float) -> str:
     """
     mktimestamp returns the timecode of the subtitle.
 
@@ -39,7 +40,7 @@ class SubMaker:
     SubMaker class
     """
 
-    def __init__(self, overlapping=1):
+    def __init__(self, overlapping: int = 1) -> None:
         """
         SubMaker constructor.
 
@@ -47,10 +48,11 @@ class SubMaker:
             overlapping (int): The amount of time in seconds that the
                                subtitles should overlap.
         """
-        self.subs_and_offset = []
-        self.overlapping = overlapping * (10**7)
+        self.offset: List[Tuple[float, float]] = []
+        self.subs: List[str] = []
+        self.overlapping: int = overlapping * (10**7)
 
-    def create_sub(self, timestamp, text):
+    def create_sub(self, timestamp: Tuple[float, float], text: str) -> None:
         """
         create_sub creates a subtitle with the given timestamp and text
         and adds it to the list of subtitles
@@ -62,40 +64,37 @@ class SubMaker:
         Returns:
             None
         """
-        timestamp[1] += timestamp[0]
-        self.subs_and_offset.append(timestamp)
-        self.subs_and_offset.append(text)
+        self.offset.append((timestamp[0], timestamp[0] + timestamp[1]))
+        self.subs.append(text)
 
-    def generate_subs(self):
+    def generate_subs(self) -> str:
         """
         generate_subs generates the complete subtitle file.
 
         Returns:
             str: The complete subtitle file.
         """
-        if len(self.subs_and_offset) >= 2:
+        if len(self.subs) == len(self.offset):
             data = "WEBVTT\r\n\r\n"
-            for offset, subs in zip(
-                self.subs_and_offset[::2], self.subs_and_offset[1::2]
-            ):
+            for offset, subs in zip(self.offset, self.subs):
                 subs = unescape(subs)
-                subs = [subs[i : i + 79] for i in range(0, len(subs), 79)]
+                split_subs: List[str] = [subs[i : i + 79] for i in range(0, len(subs), 79)]
 
-                for i in range(len(subs) - 1):
-                    sub = subs[i]
+                for i in range(len(split_subs) - 1):
+                    sub = split_subs[i]
                     split_at_word = True
                     if sub[-1] == " ":
-                        subs[i] = sub[:-1]
+                        split_subs[i] = sub[:-1]
                         split_at_word = False
 
                     if sub[0] == " ":
-                        subs[i] = sub[1:]
+                        split_subs[i] = sub[1:]
                         split_at_word = False
 
                     if split_at_word:
-                        subs[i] += "-"
+                        split_subs[i] += "-"
 
-                subs = "\r\n".join(subs)
+                subs = "\r\n".join(split_subs)
 
                 data += formatter(offset[0], offset[1] + self.overlapping, subs)
             return data
diff --git a/src/edge_tts/util.py b/src/edge_tts/util.py
index 8c403a3..132896c 100644
--- a/src/edge_tts/util.py
+++ b/src/edge_tts/util.py
@@ -5,12 +5,14 @@ Main package.
 
 import argparse
 import asyncio
+from io import BufferedWriter
 import sys
+from typing import Any
 
 from edge_tts import Communicate, SubMaker, list_voices
 
 
-async def _print_voices(proxy):
+async def _print_voices(*, proxy: str) -> None:
     """Print all available voices."""
     for idx, voice in enumerate(await list_voices(proxy=proxy)):
         if idx != 0:
@@ -23,9 +25,9 @@ async def _print_voices(proxy):
             print(f"{key}: {voice[key]}")
 
 
-async def _run_tts(args):
+async def _run_tts(args: Any) -> None:
     """Run TTS after parsing arguments from command line."""
-    tts = await Communicate(
+    tts = Communicate(
         args.text,
         args.voice,
         proxy=args.proxy,
@@ -35,18 +37,17 @@ async def _run_tts(args):
     try:
         media_file = None
         if args.write_media:
-            # pylint: disable=consider-using-with
             media_file = open(args.write_media, "wb")
 
         subs = SubMaker(args.overlapping)
         async for data in tts.stream():
             if data["type"] == "audio":
-                if not args.write_media:
-                    sys.stdout.buffer.write(data["data"])
-                else:
+                if isinstance(media_file, BufferedWriter):
                     media_file.write(data["data"])
+                else:
+                    sys.stdout.buffer.write(data["data"])                    
             elif data["type"] == "WordBoundary":
-                subs.create_sub([data["offset"], data["duration"]], data["text"])
+                subs.create_sub((data["offset"], data["duration"]), data["text"])
 
         if not args.write_subtitles:
             sys.stderr.write(subs.generate_subs())
@@ -58,7 +59,7 @@ async def _run_tts(args):
             media_file.close()
 
 
-async def _async_main():
+async def _async_main() -> None:
     parser = argparse.ArgumentParser(description="Microsoft Edge TTS")
     group = parser.add_mutually_exclusive_group(required=True)
     group.add_argument("-t", "--text", help="what TTS will say")
@@ -111,7 +112,7 @@ async def _async_main():
     args = parser.parse_args()
 
     if args.list_voices:
-        await _print_voices(args.proxy)
+        await _print_voices(proxy=args.proxy)
         sys.exit(0)
 
     if args.text is not None or args.file is not None:
@@ -129,7 +130,7 @@ async def _async_main():
         await _run_tts(args)
 
 
-def main():
+def main() -> None:
     """Run the main function using asyncio."""
     asyncio.get_event_loop().run_until_complete(_async_main())