diff --git a/poetry.lock b/poetry.lock
index 6ccac8c..6ac227f 100644
--- a/poetry.lock
+++ b/poetry.lock
@@ -1,10 +1,9 @@
-# This file is automatically @generated by Poetry 1.4.2 and should not be changed by hand.
+# This file is automatically @generated by Poetry 1.6.1 and should not be changed by hand.
 
 [[package]]
 name = "anyio"
 version = "3.7.1"
 description = "High level compatibility layer for multiple asynchronous event loop implementations"
-category = "main"
 optional = false
 python-versions = ">=3.7"
 files = [
@@ -27,7 +26,6 @@ trio = ["trio (<0.22)"]
 name = "certifi"
 version = "2023.7.22"
 description = "Python package for providing Mozilla's CA Bundle."
-category = "main"
 optional = false
 python-versions = ">=3.6"
 files = [
@@ -39,7 +37,6 @@ files = [
 name = "colorama"
 version = "0.4.6"
 description = "Cross-platform colored terminal text."
-category = "dev"
 optional = false
 python-versions = "!=3.0.*,!=3.1.*,!=3.2.*,!=3.3.*,!=3.4.*,!=3.5.*,!=3.6.*,>=2.7"
 files = [
@@ -51,7 +48,6 @@ files = [
 name = "coverage"
 version = "7.2.7"
 description = "Code coverage measurement for Python"
-category = "dev"
 optional = false
 python-versions = ">=3.7"
 files = [
@@ -127,7 +123,6 @@ toml = ["tomli"]
 name = "exceptiongroup"
 version = "1.1.3"
 description = "Backport of PEP 654 (exception groups)"
-category = "main"
 optional = false
 python-versions = ">=3.7"
 files = [
@@ -142,7 +137,6 @@ test = ["pytest (>=6)"]
 name = "h11"
 version = "0.14.0"
 description = "A pure-Python, bring-your-own-I/O implementation of HTTP/1.1"
-category = "main"
 optional = false
 python-versions = ">=3.7"
 files = [
@@ -157,7 +151,6 @@ typing-extensions = {version = "*", markers = "python_version < \"3.8\""}
 name = "httpcore"
 version = "0.16.3"
 description = "A minimal low-level HTTP client."
-category = "main"
 optional = false
 python-versions = ">=3.7"
 files = [
@@ -169,17 +162,16 @@ files = [
 anyio = ">=3.0,<5.0"
 certifi = "*"
 h11 = ">=0.13,<0.15"
-sniffio = ">=1.0.0,<2.0.0"
+sniffio = "==1.*"
 
 [package.extras]
 http2 = ["h2 (>=3,<5)"]
-socks = ["socksio (>=1.0.0,<2.0.0)"]
+socks = ["socksio (==1.*)"]
 
 [[package]]
 name = "httpx"
 version = "0.23.3"
 description = "The next generation HTTP client."
-category = "main"
 optional = false
 python-versions = ">=3.7"
 files = [
@@ -195,15 +187,14 @@ sniffio = "*"
 
 [package.extras]
 brotli = ["brotli", "brotlicffi"]
-cli = ["click (>=8.0.0,<9.0.0)", "pygments (>=2.0.0,<3.0.0)", "rich (>=10,<13)"]
+cli = ["click (==8.*)", "pygments (==2.*)", "rich (>=10,<13)"]
 http2 = ["h2 (>=3,<5)"]
-socks = ["socksio (>=1.0.0,<2.0.0)"]
+socks = ["socksio (==1.*)"]
 
 [[package]]
 name = "idna"
 version = "3.4"
 description = "Internationalized Domain Names in Applications (IDNA)"
-category = "main"
 optional = false
 python-versions = ">=3.5"
 files = [
@@ -215,7 +206,6 @@ files = [
 name = "importlib-metadata"
 version = "6.7.0"
 description = "Read metadata from Python packages"
-category = "dev"
 optional = false
 python-versions = ">=3.7"
 files = [
@@ -236,7 +226,6 @@ testing = ["flufl.flake8", "importlib-resources (>=1.3)", "packaging", "pyfakefs
 name = "iniconfig"
 version = "2.0.0"
 description = "brain-dead simple config-ini parsing"
-category = "dev"
 optional = false
 python-versions = ">=3.7"
 files = [
@@ -248,7 +237,6 @@ files = [
 name = "packaging"
 version = "23.1"
 description = "Core utilities for Python packages"
-category = "dev"
 optional = false
 python-versions = ">=3.7"
 files = [
@@ -260,7 +248,6 @@ files = [
 name = "pluggy"
 version = "1.2.0"
 description = "plugin and hook calling mechanisms for python"
-category = "dev"
 optional = false
 python-versions = ">=3.7"
 files = [
@@ -279,7 +266,6 @@ testing = ["pytest", "pytest-benchmark"]
 name = "pytest"
 version = "7.4.0"
 description = "pytest: simple powerful testing with Python"
-category = "dev"
 optional = false
 python-versions = ">=3.7"
 files = [
@@ -303,7 +289,6 @@ testing = ["argcomplete", "attrs (>=19.2.0)", "hypothesis (>=3.56)", "mock", "no
 name = "pytest-asyncio"
 version = "0.20.3"
 description = "Pytest support for asyncio"
-category = "dev"
 optional = false
 python-versions = ">=3.7"
 files = [
@@ -323,7 +308,6 @@ testing = ["coverage (>=6.2)", "flaky (>=3.5.0)", "hypothesis (>=5.7.1)", "mypy
 name = "pytest-cov"
 version = "4.1.0"
 description = "Pytest plugin for measuring coverage."
-category = "dev"
 optional = false
 python-versions = ">=3.7"
 files = [
@@ -342,7 +326,6 @@ testing = ["fields", "hunter", "process-tests", "pytest-xdist", "six", "virtuale
 name = "python-dateutil"
 version = "2.8.2"
 description = "Extensions to the standard Python datetime module"
-category = "main"
 optional = false
 python-versions = "!=3.0.*,!=3.1.*,!=3.2.*,>=2.7"
 files = [
@@ -357,7 +340,6 @@ six = ">=1.5"
 name = "respx"
 version = "0.20.2"
 description = "A utility for mocking out the Python HTTPX and HTTP Core libraries."
-category = "dev"
 optional = false
 python-versions = ">=3.7"
 files = [
@@ -372,7 +354,6 @@ httpx = ">=0.21.0"
 name = "rfc3986"
 version = "1.5.0"
 description = "Validating URI References per RFC 3986"
-category = "main"
 optional = false
 python-versions = "*"
 files = [
@@ -390,7 +371,6 @@ idna2008 = ["idna"]
 name = "six"
 version = "1.16.0"
 description = "Python 2 and 3 compatibility utilities"
-category = "main"
 optional = false
 python-versions = ">=2.7, !=3.0.*, !=3.1.*, !=3.2.*"
 files = [
@@ -402,7 +382,6 @@ files = [
 name = "sniffio"
 version = "1.3.0"
 description = "Sniff out which async library your code is running under"
-category = "main"
 optional = false
 python-versions = ">=3.7"
 files = [
@@ -414,7 +393,6 @@ files = [
 name = "tomli"
 version = "2.0.1"
 description = "A lil' TOML parser"
-category = "dev"
 optional = false
 python-versions = ">=3.7"
 files = [
@@ -426,7 +404,6 @@ files = [
 name = "typing-extensions"
 version = "4.7.1"
 description = "Backported and Experimental Type Hints for Python 3.7+"
-category = "main"
 optional = false
 python-versions = ">=3.7"
 files = [
@@ -438,7 +415,6 @@ files = [
 name = "zipp"
 version = "3.15.0"
 description = "Backport of pathlib-compatible object wrapper for zip files"
-category = "dev"
 optional = false
 python-versions = ">=3.7"
 files = [
@@ -453,4 +429,4 @@ testing = ["big-O", "flake8 (<5)", "jaraco.functools", "jaraco.itertools", "more
 [metadata]
 lock-version = "2.0"
 python-versions = "^3.7"
-content-hash = "5c06df5db167647617c8fb7afc9da451dcec9d10e24df37e6024124cccd6da60"
+content-hash = "21400e8862cff02e2f4a774aacc9985773cb54ecfbb0982200c6c5418a219663"
diff --git a/pyproject.toml b/pyproject.toml
index dd54dd1..3beac06 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -15,6 +15,7 @@ repository = "https://github.com/1Password/connect-sdk-python"
 python = "^3.7"
 python-dateutil = "^2.8.1"
 httpx = "^0.23.3"
+typing-extensions = "<4.8.0"
 
 [tool.poetry.group.dev.dependencies]
 pytest = "^7.2.0"
diff --git a/src/onepasswordconnectsdk/async_client.py b/src/onepasswordconnectsdk/async_client.py
index 415924c..aadfb60 100644
--- a/src/onepasswordconnectsdk/async_client.py
+++ b/src/onepasswordconnectsdk/async_client.py
@@ -3,6 +3,7 @@
 from httpx import HTTPError
 import json
 import os
+from typing import Optional
 
 from onepasswordconnectsdk.serializer import Serializer
 from onepasswordconnectsdk.utils import build_headers, is_valid_uuid, PathBuilder
@@ -56,7 +57,7 @@ async def get_files(self, item_id: str, vault_id: str):
             )
         return self.serializer.deserialize(response.content, "list[File]")
 
-    async def get_file_content(self, file_id: str, item_id: str, vault_id: str, content_path: str = None):
+    async def get_file_content(self, file_id: str, item_id: str, vault_id: str, content_path: Optional[str] = None):
         url = content_path
         if content_path is None:
             url = PathBuilder().vaults(vault_id).items(item_id).files(file_id).content().build()
@@ -164,7 +165,7 @@ async def get_item_by_title(self, title: str, vault_id: str):
         item_summary = self.serializer.deserialize(response.content, "list[SummaryItem]")[0]
         return await self.get_item_by_id(item_summary.id, vault_id)
 
-    async def get_items(self, vault_id: str, filter_query: str = None):
+    async def get_items(self, vault_id: str, filter_query: Optional[str] = None):
         """Returns a list of item summaries for the specified vault
 
         Args:
diff --git a/src/onepasswordconnectsdk/client.py b/src/onepasswordconnectsdk/client.py
index 4202ccf..12cd713 100644
--- a/src/onepasswordconnectsdk/client.py
+++ b/src/onepasswordconnectsdk/client.py
@@ -3,6 +3,8 @@
 from httpx import HTTPError
 import json
 import os
+from typing import Optional, Union, overload
+from typing_extensions import Literal
 
 from onepasswordconnectsdk.async_client import AsyncClient
 from onepasswordconnectsdk.serializer import Serializer
@@ -63,7 +65,7 @@ def get_files(self, item_id: str, vault_id: str):
             )
         return self.serializer.deserialize(response.content, "list[File]")
 
-    def get_file_content(self, file_id: str, item_id: str, vault_id: str, content_path: str = None):
+    def get_file_content(self, file_id: str, item_id: str, vault_id: str, content_path: Optional[str] = None):
         url = content_path
         if content_path is None:
             url = PathBuilder().vaults(vault_id).items(item_id).files(file_id).content().build()
@@ -170,7 +172,7 @@ def get_item_by_title(self, title: str, vault_id: str):
         item_summary = self.serializer.deserialize(response.content, "list[SummaryItem]")[0]
         return self.get_item_by_id(item_summary.id, vault_id)
 
-    def get_items(self, vault_id: str, filter_query: str = None):
+    def get_items(self, vault_id: str, filter_query: Optional[str] = None):
         """Returns a list of item summaries for the specified vault
 
         Args:
@@ -380,7 +382,29 @@ def sanitize_for_serialization(self, obj):
         return self.serializer.sanitize_for_serialization(obj)
 
 
-def new_client(url: str, token: str, is_async: bool = False):
+@overload
+def new_client(
+    url: str, token: str, is_async: Literal[False] = ...
+) -> Client:
+    ...
+
+
+@overload
+def new_client(
+    url: str, token: str, is_async: Literal[True] = ...
+) -> AsyncClient:
+    ...
+
+@overload
+def new_client(
+    url: str, token: str, is_async: bool = ...
+) -> Union[Client, AsyncClient]:
+    ...
+
+
+def new_client(
+    url: str, token: str, is_async: bool = False
+) -> Union[Client, AsyncClient]:
     """Builds a new client for interacting with 1Password Connect
     Parameters:
     url: The url of the 1Password Connect API
@@ -395,19 +419,45 @@ def new_client(url: str, token: str, is_async: bool = False):
     return Client(url, token)
 
 
-def new_client_from_environment(url: str = None):
+@overload
+def new_client_from_environment(
+    url: Optional[str] = ..., is_async: Literal[False] = ...
+) -> Client:
+    ...
+
+
+@overload
+def new_client_from_environment(
+    url: Optional[str] = ..., is_async: Literal[True] = ...
+) -> AsyncClient:
+    ...
+
+
+@overload
+def new_client_from_environment(
+    url: Optional[str] = ..., is_async: None = ...
+) -> Union[Client, AsyncClient]:
+    ...
+
+
+def new_client_from_environment(
+    url: Optional[str] = None, is_async: Optional[bool] = None
+) -> Union[Client, AsyncClient]:
     """Builds a new client for interacting with 1Password Connect
     using the OP_TOKEN environment variable
 
     Parameters:
     url: The url of the 1Password Connect API
-    token: The 1Password Service Account token
+    is_async: If set to True, return an async client; if False, return a sync client.
+       If not set or set to None, return an async client if the OP_CONNECT_CLIENT_ASYNC
+       environment variable is set to "True", a sync client otherwise.
 
     Returns:
-    Client: The 1Password Connect client
+    Client or AsyncClient: The 1Password Connect client
     """
     token = os.environ.get(ENV_SERVICE_ACCOUNT_JWT_VARIABLE)
-    is_async = os.environ.get(ENV_IS_ASYNC_CLIENT) == "True"
+    if is_async is None:
+        is_async = os.environ.get(ENV_IS_ASYNC_CLIENT).lower() in ("t", "true", "1")
 
     if url is None:
         url = os.environ.get(CONNECT_HOST_ENV_VARIABLE)
diff --git a/src/onepasswordconnectsdk/config.py b/src/onepasswordconnectsdk/config.py
index 7398232..5beeaf2 100644
--- a/src/onepasswordconnectsdk/config.py
+++ b/src/onepasswordconnectsdk/config.py
@@ -1,6 +1,6 @@
 import os
 import shlex
-from typing import List, Dict
+from typing import List, Dict, Optional
 from onepasswordconnectsdk.client import Client
 from onepasswordconnectsdk.models import (
     SummaryItem,
@@ -166,7 +166,7 @@ def _set_values_for_item(
     client: Client,
     parsed_item: ParsedItem,
     config_dict={},
-    config_object: object = None,
+    config_object: Optional[object] = None,
 ):
     # Fetching the full item
     item: Item = client.get_item(parsed_item.item_title, parsed_item.vault_uuid)
diff --git a/src/onepasswordconnectsdk/utils.py b/src/onepasswordconnectsdk/utils.py
index da35d50..efe7286 100644
--- a/src/onepasswordconnectsdk/utils.py
+++ b/src/onepasswordconnectsdk/utils.py
@@ -1,3 +1,6 @@
+from typing import Optional
+
+
 UUIDLength = 26
 
 
@@ -27,19 +30,19 @@ def __init__(self, version: str = "/v1"):
     def build(self) -> str:
         return self.path
 
-    def vaults(self, uuid: str = None) -> 'PathBuilder':
+    def vaults(self, uuid: Optional[str] = None) -> 'PathBuilder':
         self._append_path("vaults")
         if uuid is not None:
             self._append_path(uuid)
         return self
 
-    def items(self, uuid: str = None) -> 'PathBuilder':
+    def items(self, uuid: Optional[str] = None) -> 'PathBuilder':
         self._append_path("items")
         if uuid is not None:
             self._append_path(uuid)
         return self
 
-    def files(self, uuid: str = None) -> 'PathBuilder':
+    def files(self, uuid: Optional[str] = None) -> 'PathBuilder':
         self._append_path("files")
         if uuid is not None:
             self._append_path(uuid)
@@ -54,7 +57,7 @@ def query(self, key: str, value: str) -> 'PathBuilder':
         self._append_path(query=key_value_pair)
         return self
 
-    def _append_path(self, path_chunk: str = None, query: str = None) -> 'PathBuilder':
+    def _append_path(self, path_chunk: Optional[str] = None, query: Optional[str] = None) -> 'PathBuilder':
         if path_chunk is not None:
             self.path += f"/{path_chunk}"
         if query is not None: