diff --git a/openfeature/api.py b/openfeature/api.py
index d2b22e9d..7e06c886 100644
--- a/openfeature/api.py
+++ b/openfeature/api.py
@@ -1,5 +1,3 @@
-import typing
-
 from openfeature import _event_support
 from openfeature.client import OpenFeatureClient
 from openfeature.evaluation_context import (
@@ -40,14 +38,12 @@
 
 
 def get_client(
-    domain: typing.Optional[str] = None, version: typing.Optional[str] = None
+    domain: str | None = None, version: str | None = None
 ) -> OpenFeatureClient:
     return OpenFeatureClient(domain=domain, version=version)
 
 
-def set_provider(
-    provider: FeatureProvider, domain: typing.Optional[str] = None
-) -> None:
+def set_provider(provider: FeatureProvider, domain: str | None = None) -> None:
     if domain is None:
         provider_registry.set_default_provider(provider)
     else:
@@ -59,7 +55,7 @@ def clear_providers() -> None:
     _event_support.clear()
 
 
-def get_provider_metadata(domain: typing.Optional[str] = None) -> Metadata:
+def get_provider_metadata(domain: str | None = None) -> Metadata:
     return provider_registry.get_provider(domain).get_metadata()
 
 
diff --git a/openfeature/client.py b/openfeature/client.py
index 42690f9e..a02693c1 100644
--- a/openfeature/client.py
+++ b/openfeature/client.py
@@ -43,16 +43,10 @@
 
 TypeMap = dict[
     FlagType,
-    typing.Union[
-        type[bool],
-        type[int],
-        type[float],
-        type[str],
-        tuple[type[dict], type[list]],
-    ],
+    type[bool] | type[int] | type[float] | type[str] | tuple[type[dict], type[list]],
 ]
 
-T = typing.TypeVar("T", bool, int, float, str, typing.Union[dict, list])
+T = typing.TypeVar("T", bool, int, float, str, dict | list)
 
 
 class ResolveDetailsCallable(typing.Protocol[T]):
@@ -60,7 +54,7 @@ def __call__(
         self,
         flag_key: str,
         default_value: T,
-        evaluation_context: typing.Optional[EvaluationContext],
+        evaluation_context: EvaluationContext | None,
     ) -> FlagResolutionDetails[T]: ...
 
 
@@ -69,23 +63,23 @@ def __call__(
         self,
         flag_key: str,
         default_value: T,
-        evaluation_context: typing.Optional[EvaluationContext],
+        evaluation_context: EvaluationContext | None,
     ) -> Awaitable[FlagResolutionDetails[T]]: ...
 
 
 @dataclass
 class ClientMetadata:
-    name: typing.Optional[str] = None
-    domain: typing.Optional[str] = None
+    name: str | None = None
+    domain: str | None = None
 
 
 class OpenFeatureClient:
     def __init__(
         self,
-        domain: typing.Optional[str],
-        version: typing.Optional[str],
-        context: typing.Optional[EvaluationContext] = None,
-        hooks: typing.Optional[list[Hook]] = None,
+        domain: str | None,
+        version: str | None,
+        context: EvaluationContext | None = None,
+        hooks: list[Hook] | None = None,
     ) -> None:
         self.domain = domain
         self.version = version
@@ -109,8 +103,8 @@ def get_boolean_value(
         self,
         flag_key: str,
         default_value: bool,
-        evaluation_context: typing.Optional[EvaluationContext] = None,
-        flag_evaluation_options: typing.Optional[FlagEvaluationOptions] = None,
+        evaluation_context: EvaluationContext | None = None,
+        flag_evaluation_options: FlagEvaluationOptions | None = None,
     ) -> bool:
         return self.get_boolean_details(
             flag_key,
@@ -123,8 +117,8 @@ async def get_boolean_value_async(
         self,
         flag_key: str,
         default_value: bool,
-        evaluation_context: typing.Optional[EvaluationContext] = None,
-        flag_evaluation_options: typing.Optional[FlagEvaluationOptions] = None,
+        evaluation_context: EvaluationContext | None = None,
+        flag_evaluation_options: FlagEvaluationOptions | None = None,
     ) -> bool:
         details = await self.get_boolean_details_async(
             flag_key,
@@ -138,8 +132,8 @@ def get_boolean_details(
         self,
         flag_key: str,
         default_value: bool,
-        evaluation_context: typing.Optional[EvaluationContext] = None,
-        flag_evaluation_options: typing.Optional[FlagEvaluationOptions] = None,
+        evaluation_context: EvaluationContext | None = None,
+        flag_evaluation_options: FlagEvaluationOptions | None = None,
     ) -> FlagEvaluationDetails[bool]:
         return self.evaluate_flag_details(
             FlagType.BOOLEAN,
@@ -153,8 +147,8 @@ async def get_boolean_details_async(
         self,
         flag_key: str,
         default_value: bool,
-        evaluation_context: typing.Optional[EvaluationContext] = None,
-        flag_evaluation_options: typing.Optional[FlagEvaluationOptions] = None,
+        evaluation_context: EvaluationContext | None = None,
+        flag_evaluation_options: FlagEvaluationOptions | None = None,
     ) -> FlagEvaluationDetails[bool]:
         return await self.evaluate_flag_details_async(
             FlagType.BOOLEAN,
@@ -168,8 +162,8 @@ def get_string_value(
         self,
         flag_key: str,
         default_value: str,
-        evaluation_context: typing.Optional[EvaluationContext] = None,
-        flag_evaluation_options: typing.Optional[FlagEvaluationOptions] = None,
+        evaluation_context: EvaluationContext | None = None,
+        flag_evaluation_options: FlagEvaluationOptions | None = None,
     ) -> str:
         return self.get_string_details(
             flag_key,
@@ -182,8 +176,8 @@ async def get_string_value_async(
         self,
         flag_key: str,
         default_value: str,
-        evaluation_context: typing.Optional[EvaluationContext] = None,
-        flag_evaluation_options: typing.Optional[FlagEvaluationOptions] = None,
+        evaluation_context: EvaluationContext | None = None,
+        flag_evaluation_options: FlagEvaluationOptions | None = None,
     ) -> str:
         details = await self.get_string_details_async(
             flag_key,
@@ -197,8 +191,8 @@ def get_string_details(
         self,
         flag_key: str,
         default_value: str,
-        evaluation_context: typing.Optional[EvaluationContext] = None,
-        flag_evaluation_options: typing.Optional[FlagEvaluationOptions] = None,
+        evaluation_context: EvaluationContext | None = None,
+        flag_evaluation_options: FlagEvaluationOptions | None = None,
     ) -> FlagEvaluationDetails[str]:
         return self.evaluate_flag_details(
             FlagType.STRING,
@@ -212,8 +206,8 @@ async def get_string_details_async(
         self,
         flag_key: str,
         default_value: str,
-        evaluation_context: typing.Optional[EvaluationContext] = None,
-        flag_evaluation_options: typing.Optional[FlagEvaluationOptions] = None,
+        evaluation_context: EvaluationContext | None = None,
+        flag_evaluation_options: FlagEvaluationOptions | None = None,
     ) -> FlagEvaluationDetails[str]:
         return await self.evaluate_flag_details_async(
             FlagType.STRING,
@@ -227,8 +221,8 @@ def get_integer_value(
         self,
         flag_key: str,
         default_value: int,
-        evaluation_context: typing.Optional[EvaluationContext] = None,
-        flag_evaluation_options: typing.Optional[FlagEvaluationOptions] = None,
+        evaluation_context: EvaluationContext | None = None,
+        flag_evaluation_options: FlagEvaluationOptions | None = None,
     ) -> int:
         return self.get_integer_details(
             flag_key,
@@ -241,8 +235,8 @@ async def get_integer_value_async(
         self,
         flag_key: str,
         default_value: int,
-        evaluation_context: typing.Optional[EvaluationContext] = None,
-        flag_evaluation_options: typing.Optional[FlagEvaluationOptions] = None,
+        evaluation_context: EvaluationContext | None = None,
+        flag_evaluation_options: FlagEvaluationOptions | None = None,
     ) -> int:
         details = await self.get_integer_details_async(
             flag_key,
@@ -256,8 +250,8 @@ def get_integer_details(
         self,
         flag_key: str,
         default_value: int,
-        evaluation_context: typing.Optional[EvaluationContext] = None,
-        flag_evaluation_options: typing.Optional[FlagEvaluationOptions] = None,
+        evaluation_context: EvaluationContext | None = None,
+        flag_evaluation_options: FlagEvaluationOptions | None = None,
     ) -> FlagEvaluationDetails[int]:
         return self.evaluate_flag_details(
             FlagType.INTEGER,
@@ -271,8 +265,8 @@ async def get_integer_details_async(
         self,
         flag_key: str,
         default_value: int,
-        evaluation_context: typing.Optional[EvaluationContext] = None,
-        flag_evaluation_options: typing.Optional[FlagEvaluationOptions] = None,
+        evaluation_context: EvaluationContext | None = None,
+        flag_evaluation_options: FlagEvaluationOptions | None = None,
     ) -> FlagEvaluationDetails[int]:
         return await self.evaluate_flag_details_async(
             FlagType.INTEGER,
@@ -286,8 +280,8 @@ def get_float_value(
         self,
         flag_key: str,
         default_value: float,
-        evaluation_context: typing.Optional[EvaluationContext] = None,
-        flag_evaluation_options: typing.Optional[FlagEvaluationOptions] = None,
+        evaluation_context: EvaluationContext | None = None,
+        flag_evaluation_options: FlagEvaluationOptions | None = None,
     ) -> float:
         return self.get_float_details(
             flag_key,
@@ -300,8 +294,8 @@ async def get_float_value_async(
         self,
         flag_key: str,
         default_value: float,
-        evaluation_context: typing.Optional[EvaluationContext] = None,
-        flag_evaluation_options: typing.Optional[FlagEvaluationOptions] = None,
+        evaluation_context: EvaluationContext | None = None,
+        flag_evaluation_options: FlagEvaluationOptions | None = None,
     ) -> float:
         details = await self.get_float_details_async(
             flag_key,
@@ -315,8 +309,8 @@ def get_float_details(
         self,
         flag_key: str,
         default_value: float,
-        evaluation_context: typing.Optional[EvaluationContext] = None,
-        flag_evaluation_options: typing.Optional[FlagEvaluationOptions] = None,
+        evaluation_context: EvaluationContext | None = None,
+        flag_evaluation_options: FlagEvaluationOptions | None = None,
     ) -> FlagEvaluationDetails[float]:
         return self.evaluate_flag_details(
             FlagType.FLOAT,
@@ -330,8 +324,8 @@ async def get_float_details_async(
         self,
         flag_key: str,
         default_value: float,
-        evaluation_context: typing.Optional[EvaluationContext] = None,
-        flag_evaluation_options: typing.Optional[FlagEvaluationOptions] = None,
+        evaluation_context: EvaluationContext | None = None,
+        flag_evaluation_options: FlagEvaluationOptions | None = None,
     ) -> FlagEvaluationDetails[float]:
         return await self.evaluate_flag_details_async(
             FlagType.FLOAT,
@@ -344,12 +338,10 @@ async def get_float_details_async(
     def get_object_value(
         self,
         flag_key: str,
-        default_value: typing.Union[
-            Sequence[FlagValueType], Mapping[str, FlagValueType]
-        ],
-        evaluation_context: typing.Optional[EvaluationContext] = None,
-        flag_evaluation_options: typing.Optional[FlagEvaluationOptions] = None,
-    ) -> typing.Union[Sequence[FlagValueType], Mapping[str, FlagValueType]]:
+        default_value: Sequence[FlagValueType] | Mapping[str, FlagValueType],
+        evaluation_context: EvaluationContext | None = None,
+        flag_evaluation_options: FlagEvaluationOptions | None = None,
+    ) -> Sequence[FlagValueType] | Mapping[str, FlagValueType]:
         return self.get_object_details(
             flag_key,
             default_value,
@@ -360,12 +352,10 @@ def get_object_value(
     async def get_object_value_async(
         self,
         flag_key: str,
-        default_value: typing.Union[
-            Sequence[FlagValueType], Mapping[str, FlagValueType]
-        ],
-        evaluation_context: typing.Optional[EvaluationContext] = None,
-        flag_evaluation_options: typing.Optional[FlagEvaluationOptions] = None,
-    ) -> typing.Union[Sequence[FlagValueType], Mapping[str, FlagValueType]]:
+        default_value: Sequence[FlagValueType] | Mapping[str, FlagValueType],
+        evaluation_context: EvaluationContext | None = None,
+        flag_evaluation_options: FlagEvaluationOptions | None = None,
+    ) -> Sequence[FlagValueType] | Mapping[str, FlagValueType]:
         details = await self.get_object_details_async(
             flag_key,
             default_value,
@@ -377,14 +367,10 @@ async def get_object_value_async(
     def get_object_details(
         self,
         flag_key: str,
-        default_value: typing.Union[
-            Sequence[FlagValueType], Mapping[str, FlagValueType]
-        ],
-        evaluation_context: typing.Optional[EvaluationContext] = None,
-        flag_evaluation_options: typing.Optional[FlagEvaluationOptions] = None,
-    ) -> FlagEvaluationDetails[
-        typing.Union[Sequence[FlagValueType], Mapping[str, FlagValueType]]
-    ]:
+        default_value: Sequence[FlagValueType] | Mapping[str, FlagValueType],
+        evaluation_context: EvaluationContext | None = None,
+        flag_evaluation_options: FlagEvaluationOptions | None = None,
+    ) -> FlagEvaluationDetails[Sequence[FlagValueType] | Mapping[str, FlagValueType]]:
         return self.evaluate_flag_details(
             FlagType.OBJECT,
             flag_key,
@@ -396,14 +382,10 @@ def get_object_details(
     async def get_object_details_async(
         self,
         flag_key: str,
-        default_value: typing.Union[
-            Sequence[FlagValueType], Mapping[str, FlagValueType]
-        ],
-        evaluation_context: typing.Optional[EvaluationContext] = None,
-        flag_evaluation_options: typing.Optional[FlagEvaluationOptions] = None,
-    ) -> FlagEvaluationDetails[
-        typing.Union[Sequence[FlagValueType], Mapping[str, FlagValueType]]
-    ]:
+        default_value: Sequence[FlagValueType] | Mapping[str, FlagValueType],
+        evaluation_context: EvaluationContext | None = None,
+        flag_evaluation_options: FlagEvaluationOptions | None = None,
+    ) -> FlagEvaluationDetails[Sequence[FlagValueType] | Mapping[str, FlagValueType]]:
         return await self.evaluate_flag_details_async(
             FlagType.OBJECT,
             flag_key,
@@ -417,8 +399,8 @@ def _establish_hooks_and_provider(
         flag_type: FlagType,
         flag_key: str,
         default_value: FlagValueType,
-        evaluation_context: typing.Optional[EvaluationContext],
-        flag_evaluation_options: typing.Optional[FlagEvaluationOptions],
+        evaluation_context: EvaluationContext | None,
+        flag_evaluation_options: FlagEvaluationOptions | None,
     ) -> tuple[
         FeatureProvider,
         HookHints,
@@ -485,7 +467,7 @@ def _establish_hooks_and_provider(
 
     def _assert_provider_status(
         self,
-    ) -> typing.Optional[OpenFeatureError]:
+    ) -> OpenFeatureError | None:
         status = self.get_provider_status()
         if status == ProviderStatus.NOT_READY:
             return ProviderNotReadyError()
@@ -518,8 +500,8 @@ async def evaluate_flag_details_async(
         flag_type: FlagType,
         flag_key: str,
         default_value: bool,
-        evaluation_context: typing.Optional[EvaluationContext] = None,
-        flag_evaluation_options: typing.Optional[FlagEvaluationOptions] = None,
+        evaluation_context: EvaluationContext | None = None,
+        flag_evaluation_options: FlagEvaluationOptions | None = None,
     ) -> FlagEvaluationDetails[bool]: ...
 
     @typing.overload
@@ -528,8 +510,8 @@ async def evaluate_flag_details_async(
         flag_type: FlagType,
         flag_key: str,
         default_value: int,
-        evaluation_context: typing.Optional[EvaluationContext] = None,
-        flag_evaluation_options: typing.Optional[FlagEvaluationOptions] = None,
+        evaluation_context: EvaluationContext | None = None,
+        flag_evaluation_options: FlagEvaluationOptions | None = None,
     ) -> FlagEvaluationDetails[int]: ...
 
     @typing.overload
@@ -538,8 +520,8 @@ async def evaluate_flag_details_async(
         flag_type: FlagType,
         flag_key: str,
         default_value: float,
-        evaluation_context: typing.Optional[EvaluationContext] = None,
-        flag_evaluation_options: typing.Optional[FlagEvaluationOptions] = None,
+        evaluation_context: EvaluationContext | None = None,
+        flag_evaluation_options: FlagEvaluationOptions | None = None,
     ) -> FlagEvaluationDetails[float]: ...
 
     @typing.overload
@@ -548,8 +530,8 @@ async def evaluate_flag_details_async(
         flag_type: FlagType,
         flag_key: str,
         default_value: str,
-        evaluation_context: typing.Optional[EvaluationContext] = None,
-        flag_evaluation_options: typing.Optional[FlagEvaluationOptions] = None,
+        evaluation_context: EvaluationContext | None = None,
+        flag_evaluation_options: FlagEvaluationOptions | None = None,
     ) -> FlagEvaluationDetails[str]: ...
 
     @typing.overload
@@ -558,8 +540,8 @@ async def evaluate_flag_details_async(
         flag_type: FlagType,
         flag_key: str,
         default_value: Sequence["FlagValueType"],
-        evaluation_context: typing.Optional[EvaluationContext] = None,
-        flag_evaluation_options: typing.Optional[FlagEvaluationOptions] = None,
+        evaluation_context: EvaluationContext | None = None,
+        flag_evaluation_options: FlagEvaluationOptions | None = None,
     ) -> FlagEvaluationDetails[Sequence["FlagValueType"]]: ...
 
     @typing.overload
@@ -568,8 +550,8 @@ async def evaluate_flag_details_async(
         flag_type: FlagType,
         flag_key: str,
         default_value: Mapping[str, "FlagValueType"],
-        evaluation_context: typing.Optional[EvaluationContext] = None,
-        flag_evaluation_options: typing.Optional[FlagEvaluationOptions] = None,
+        evaluation_context: EvaluationContext | None = None,
+        flag_evaluation_options: FlagEvaluationOptions | None = None,
     ) -> FlagEvaluationDetails[Mapping[str, "FlagValueType"]]: ...
 
     async def evaluate_flag_details_async(
@@ -577,8 +559,8 @@ async def evaluate_flag_details_async(
         flag_type: FlagType,
         flag_key: str,
         default_value: FlagValueType,
-        evaluation_context: typing.Optional[EvaluationContext] = None,
-        flag_evaluation_options: typing.Optional[FlagEvaluationOptions] = None,
+        evaluation_context: EvaluationContext | None = None,
+        flag_evaluation_options: FlagEvaluationOptions | None = None,
     ) -> FlagEvaluationDetails[FlagValueType]:
         """
         Evaluate the flag requested by the user from the clients provider.
@@ -694,8 +676,8 @@ def evaluate_flag_details(
         flag_type: FlagType,
         flag_key: str,
         default_value: bool,
-        evaluation_context: typing.Optional[EvaluationContext] = None,
-        flag_evaluation_options: typing.Optional[FlagEvaluationOptions] = None,
+        evaluation_context: EvaluationContext | None = None,
+        flag_evaluation_options: FlagEvaluationOptions | None = None,
     ) -> FlagEvaluationDetails[bool]: ...
 
     @typing.overload
@@ -704,8 +686,8 @@ def evaluate_flag_details(
         flag_type: FlagType,
         flag_key: str,
         default_value: int,
-        evaluation_context: typing.Optional[EvaluationContext] = None,
-        flag_evaluation_options: typing.Optional[FlagEvaluationOptions] = None,
+        evaluation_context: EvaluationContext | None = None,
+        flag_evaluation_options: FlagEvaluationOptions | None = None,
     ) -> FlagEvaluationDetails[int]: ...
 
     @typing.overload
@@ -714,8 +696,8 @@ def evaluate_flag_details(
         flag_type: FlagType,
         flag_key: str,
         default_value: float,
-        evaluation_context: typing.Optional[EvaluationContext] = None,
-        flag_evaluation_options: typing.Optional[FlagEvaluationOptions] = None,
+        evaluation_context: EvaluationContext | None = None,
+        flag_evaluation_options: FlagEvaluationOptions | None = None,
     ) -> FlagEvaluationDetails[float]: ...
 
     @typing.overload
@@ -724,8 +706,8 @@ def evaluate_flag_details(
         flag_type: FlagType,
         flag_key: str,
         default_value: str,
-        evaluation_context: typing.Optional[EvaluationContext] = None,
-        flag_evaluation_options: typing.Optional[FlagEvaluationOptions] = None,
+        evaluation_context: EvaluationContext | None = None,
+        flag_evaluation_options: FlagEvaluationOptions | None = None,
     ) -> FlagEvaluationDetails[str]: ...
 
     @typing.overload
@@ -734,8 +716,8 @@ def evaluate_flag_details(
         flag_type: FlagType,
         flag_key: str,
         default_value: Sequence["FlagValueType"],
-        evaluation_context: typing.Optional[EvaluationContext] = None,
-        flag_evaluation_options: typing.Optional[FlagEvaluationOptions] = None,
+        evaluation_context: EvaluationContext | None = None,
+        flag_evaluation_options: FlagEvaluationOptions | None = None,
     ) -> FlagEvaluationDetails[Sequence["FlagValueType"]]: ...
 
     @typing.overload
@@ -744,8 +726,8 @@ def evaluate_flag_details(
         flag_type: FlagType,
         flag_key: str,
         default_value: Mapping[str, "FlagValueType"],
-        evaluation_context: typing.Optional[EvaluationContext] = None,
-        flag_evaluation_options: typing.Optional[FlagEvaluationOptions] = None,
+        evaluation_context: EvaluationContext | None = None,
+        flag_evaluation_options: FlagEvaluationOptions | None = None,
     ) -> FlagEvaluationDetails[Mapping[str, "FlagValueType"]]: ...
 
     def evaluate_flag_details(
@@ -753,8 +735,8 @@ def evaluate_flag_details(
         flag_type: FlagType,
         flag_key: str,
         default_value: FlagValueType,
-        evaluation_context: typing.Optional[EvaluationContext] = None,
-        flag_evaluation_options: typing.Optional[FlagEvaluationOptions] = None,
+        evaluation_context: EvaluationContext | None = None,
+        flag_evaluation_options: FlagEvaluationOptions | None = None,
     ) -> FlagEvaluationDetails[FlagValueType]:
         """
         Evaluate the flag requested by the user from the clients provider.
@@ -872,7 +854,7 @@ async def _create_provider_evaluation_async(
         flag_type: FlagType,
         flag_key: str,
         default_value: FlagValueType,
-        evaluation_context: typing.Optional[EvaluationContext] = None,
+        evaluation_context: EvaluationContext | None = None,
     ) -> FlagEvaluationDetails[FlagValueType]:
         get_details_callables_async: Mapping[FlagType, ResolveDetailsCallableAsync] = {
             FlagType.BOOLEAN: provider.resolve_boolean_details_async,
@@ -917,7 +899,7 @@ def _create_provider_evaluation(
         flag_type: FlagType,
         flag_key: str,
         default_value: FlagValueType,
-        evaluation_context: typing.Optional[EvaluationContext] = None,
+        evaluation_context: EvaluationContext | None = None,
     ) -> FlagEvaluationDetails[FlagValueType]:
         """
         Encapsulated method to create a FlagEvaluationDetail from a specific provider.
@@ -976,7 +958,7 @@ def remove_handler(self, event: ProviderEvent, handler: EventHandler) -> None:
 
 def _typecheck_flag_value(
     value: typing.Any, flag_type: FlagType
-) -> typing.Optional[OpenFeatureError]:
+) -> OpenFeatureError | None:
     type_map: TypeMap = {
         FlagType.BOOLEAN: bool,
         FlagType.STRING: str,
diff --git a/openfeature/evaluation_context/__init__.py b/openfeature/evaluation_context/__init__.py
index 948a4baf..4c046418 100644
--- a/openfeature/evaluation_context/__init__.py
+++ b/openfeature/evaluation_context/__init__.py
@@ -10,20 +10,20 @@
 __all__ = ["EvaluationContext", "get_evaluation_context", "set_evaluation_context"]
 
 # https://openfeature.dev/specification/sections/evaluation-context#requirement-312
-EvaluationContextAttribute = typing.Union[
-    bool,
-    int,
-    float,
-    str,
-    datetime,
-    Sequence["EvaluationContextAttribute"],
-    Mapping[str, "EvaluationContextAttribute"],
-]
+EvaluationContextAttribute: typing.TypeAlias = (
+    bool
+    | int
+    | float
+    | str
+    | datetime
+    | Sequence["EvaluationContextAttribute"]
+    | Mapping[str, "EvaluationContextAttribute"]
+)
 
 
 @dataclass
 class EvaluationContext:
-    targeting_key: typing.Optional[str] = None
+    targeting_key: str | None = None
     attributes: Mapping[str, EvaluationContextAttribute] = field(default_factory=dict)
 
     def merge(self, ctx2: EvaluationContext) -> EvaluationContext:
diff --git a/openfeature/event.py b/openfeature/event.py
index f40ad74a..53dc3834 100644
--- a/openfeature/event.py
+++ b/openfeature/event.py
@@ -1,6 +1,5 @@
 from __future__ import annotations
 
-import typing
 from collections.abc import Callable
 from dataclasses import dataclass, field
 from enum import Enum
@@ -19,23 +18,19 @@ class ProviderEvent(Enum):
 
 @dataclass
 class ProviderEventDetails:
-    flags_changed: typing.Optional[list[str]] = None
-    message: typing.Optional[str] = None
-    error_code: typing.Optional[ErrorCode] = None
-    metadata: dict[str, typing.Union[bool, str, int, float]] = field(
-        default_factory=dict
-    )
+    flags_changed: list[str] | None = None
+    message: str | None = None
+    error_code: ErrorCode | None = None
+    metadata: dict[str, bool | str | int | float] = field(default_factory=dict)
 
 
 @dataclass
 class EventDetails(ProviderEventDetails):
     provider_name: str = ""
-    flags_changed: typing.Optional[list[str]] = None
-    message: typing.Optional[str] = None
-    error_code: typing.Optional[ErrorCode] = None
-    metadata: dict[str, typing.Union[bool, str, int, float]] = field(
-        default_factory=dict
-    )
+    flags_changed: list[str] | None = None
+    message: str | None = None
+    error_code: ErrorCode | None = None
+    metadata: dict[str, bool | str | int | float] = field(default_factory=dict)
 
     @classmethod
     def from_provider_event_details(
diff --git a/openfeature/exception.py b/openfeature/exception.py
index d4fc388f..fbd13897 100644
--- a/openfeature/exception.py
+++ b/openfeature/exception.py
@@ -1,6 +1,5 @@
 from __future__ import annotations
 
-import typing
 from collections.abc import Callable, Mapping
 
 from openfeature._backports.strenum import StrEnum
@@ -25,9 +24,7 @@ class OpenFeatureError(Exception):
     the more specific exceptions extending this one should be used.
     """
 
-    def __init__(
-        self, error_code: ErrorCode, error_message: typing.Optional[str] = None
-    ):
+    def __init__(self, error_code: ErrorCode, error_message: str | None = None):
         """
         Constructor for the generic OpenFeatureError.
         @param error_message: an optional string message representing why the
@@ -43,7 +40,7 @@ class ProviderNotReadyError(OpenFeatureError):
     This exception should be raised when the provider is not ready to be used.
     """
 
-    def __init__(self, error_message: typing.Optional[str] = None):
+    def __init__(self, error_message: str | None = None):
         """
         Constructor for the ProviderNotReadyError. The error code for this type of
         exception is ErrorCode.PROVIDER_NOT_READY.
@@ -58,7 +55,7 @@ class ProviderFatalError(OpenFeatureError):
     This exception should be raised when the provider encounters a fatal error.
     """
 
-    def __init__(self, error_message: typing.Optional[str] = None):
+    def __init__(self, error_message: str | None = None):
         """
         Constructor for the ProviderFatalError. The error code for this type of
         exception is ErrorCode.PROVIDER_FATAL.
@@ -74,7 +71,7 @@ class FlagNotFoundError(OpenFeatureError):
     key provided by the user.
     """
 
-    def __init__(self, error_message: typing.Optional[str] = None):
+    def __init__(self, error_message: str | None = None):
         """
         Constructor for the FlagNotFoundError.  The error code for
         this type of exception is ErrorCode.FLAG_NOT_FOUND.
@@ -90,7 +87,7 @@ class GeneralError(OpenFeatureError):
     feature python sdk.
     """
 
-    def __init__(self, error_message: typing.Optional[str] = None):
+    def __init__(self, error_message: str | None = None):
         """
         Constructor for the GeneralError.  The error code for this type of exception
         is ErrorCode.GENERAL.
@@ -106,7 +103,7 @@ class ParseError(OpenFeatureError):
     be parsed into a FlagEvaluationDetails object.
     """
 
-    def __init__(self, error_message: typing.Optional[str] = None):
+    def __init__(self, error_message: str | None = None):
         """
         Constructor for the ParseError. The error code for this type of exception
         is ErrorCode.PARSE_ERROR.
@@ -122,7 +119,7 @@ class TypeMismatchError(OpenFeatureError):
     not match the type requested by the user.
     """
 
-    def __init__(self, error_message: typing.Optional[str] = None):
+    def __init__(self, error_message: str | None = None):
         """
         Constructor for the TypeMismatchError. The error code for this type of
         exception is ErrorCode.TYPE_MISMATCH.
@@ -138,7 +135,7 @@ class TargetingKeyMissingError(OpenFeatureError):
     but one was not provided in the evaluation context.
     """
 
-    def __init__(self, error_message: typing.Optional[str] = None):
+    def __init__(self, error_message: str | None = None):
         """
         Constructor for the TargetingKeyMissingError. The error code for this type of
         exception is ErrorCode.TARGETING_KEY_MISSING.
@@ -154,7 +151,7 @@ class InvalidContextError(OpenFeatureError):
     requirements.
     """
 
-    def __init__(self, error_message: typing.Optional[str]):
+    def __init__(self, error_message: str | None):
         """
         Constructor for the InvalidContextError. The error code for this type of
         exception is ErrorCode.INVALID_CONTEXT.
diff --git a/openfeature/flag_evaluation.py b/openfeature/flag_evaluation.py
index 723f8bb5..df47e732 100644
--- a/openfeature/flag_evaluation.py
+++ b/openfeature/flag_evaluation.py
@@ -42,15 +42,10 @@ class Reason(StrEnum):
     UNKNOWN = "UNKNOWN"
 
 
-FlagMetadata = Mapping[str, typing.Union[bool, int, float, str]]
-FlagValueType = typing.Union[
-    bool,
-    int,
-    float,
-    str,
-    Sequence["FlagValueType"],
-    Mapping[str, "FlagValueType"],
-]
+FlagMetadata = Mapping[str, bool | int | float | str]
+FlagValueType: typing.TypeAlias = (
+    bool | int | float | str | Sequence["FlagValueType"] | Mapping[str, "FlagValueType"]
+)
 
 T_co = typing.TypeVar("T_co", covariant=True)
 
@@ -59,13 +54,13 @@ class Reason(StrEnum):
 class FlagEvaluationDetails(typing.Generic[T_co]):
     flag_key: str
     value: T_co
-    variant: typing.Optional[str] = None
+    variant: str | None = None
     flag_metadata: FlagMetadata = field(default_factory=dict)
-    reason: typing.Optional[typing.Union[str, Reason]] = None
-    error_code: typing.Optional[ErrorCode] = None
-    error_message: typing.Optional[str] = None
+    reason: str | Reason | None = None
+    error_code: ErrorCode | None = None
+    error_message: str | None = None
 
-    def get_exception(self) -> typing.Optional[OpenFeatureError]:
+    def get_exception(self) -> OpenFeatureError | None:
         if self.error_code:
             return ErrorCode.to_exception(self.error_code, self.error_message or "")
         return None
@@ -83,10 +78,10 @@ class FlagEvaluationOptions:
 @dataclass
 class FlagResolutionDetails(typing.Generic[U_co]):
     value: U_co
-    error_code: typing.Optional[ErrorCode] = None
-    error_message: typing.Optional[str] = None
-    reason: typing.Optional[typing.Union[str, Reason]] = None
-    variant: typing.Optional[str] = None
+    error_code: ErrorCode | None = None
+    error_message: str | None = None
+    reason: str | Reason | None = None
+    variant: str | None = None
     flag_metadata: FlagMetadata = field(default_factory=dict)
 
     def raise_for_error(self) -> None:
diff --git a/openfeature/hook/__init__.py b/openfeature/hook/__init__.py
index 2d5282c2..247d316b 100644
--- a/openfeature/hook/__init__.py
+++ b/openfeature/hook/__init__.py
@@ -44,9 +44,9 @@ def __init__(  # noqa: PLR0913
         flag_type: FlagType,
         default_value: FlagValueType,
         evaluation_context: EvaluationContext,
-        client_metadata: typing.Optional[ClientMetadata] = None,
-        provider_metadata: typing.Optional[Metadata] = None,
-        hook_data: typing.Optional[HookData] = None,
+        client_metadata: ClientMetadata | None = None,
+        provider_metadata: Metadata | None = None,
+        hook_data: HookData | None = None,
     ):
         self.flag_key = flag_key
         self.flag_type = flag_type
@@ -69,15 +69,15 @@ def __setattr__(self, key: str, value: typing.Any) -> None:
 
 
 # https://openfeature.dev/specification/sections/hooks/#requirement-421
-HookHintValue = typing.Union[
-    bool,
-    int,
-    float,
-    str,
-    datetime,
-    Sequence["HookHintValue"],
-    Mapping[str, "HookHintValue"],
-]
+HookHintValue: typing.TypeAlias = (
+    bool
+    | int
+    | float
+    | str
+    | datetime
+    | Sequence["HookHintValue"]
+    | Mapping[str, "HookHintValue"]
+)
 
 HookHints = Mapping[str, HookHintValue]
 
@@ -85,7 +85,7 @@ def __setattr__(self, key: str, value: typing.Any) -> None:
 class Hook:
     def before(
         self, hook_context: HookContext, hints: HookHints
-    ) -> typing.Optional[EvaluationContext]:
+    ) -> EvaluationContext | None:
         """
         Runs before flag is resolved.
 
diff --git a/openfeature/hook/_hook_support.py b/openfeature/hook/_hook_support.py
index 0a3565cd..4f292997 100644
--- a/openfeature/hook/_hook_support.py
+++ b/openfeature/hook/_hook_support.py
@@ -13,7 +13,7 @@ def error_hooks(
     flag_type: FlagType,
     exception: Exception,
     hooks_and_context: list[tuple[Hook, HookContext]],
-    hints: typing.Optional[HookHints] = None,
+    hints: HookHints | None = None,
 ) -> None:
     kwargs = {"exception": exception, "hints": hints}
     _execute_hooks(
@@ -28,7 +28,7 @@ def after_all_hooks(
     flag_type: FlagType,
     details: FlagEvaluationDetails[typing.Any],
     hooks_and_context: list[tuple[Hook, HookContext]],
-    hints: typing.Optional[HookHints] = None,
+    hints: HookHints | None = None,
 ) -> None:
     kwargs = {"details": details, "hints": hints}
     _execute_hooks(
@@ -43,7 +43,7 @@ def after_hooks(
     flag_type: FlagType,
     details: FlagEvaluationDetails[typing.Any],
     hooks_and_context: list[tuple[Hook, HookContext]],
-    hints: typing.Optional[HookHints] = None,
+    hints: HookHints | None = None,
 ) -> None:
     kwargs = {"details": details, "hints": hints}
     _execute_hooks_unchecked(
@@ -57,7 +57,7 @@ def after_hooks(
 def before_hooks(
     flag_type: FlagType,
     hooks_and_context: list[tuple[Hook, HookContext]],
-    hints: typing.Optional[HookHints] = None,
+    hints: HookHints | None = None,
 ) -> EvaluationContext:
     kwargs = {"hints": hints}
     executed_hooks = _execute_hooks_unchecked(
@@ -79,7 +79,7 @@ def _execute_hooks(
     hooks_and_context: list[tuple[Hook, HookContext]],
     hook_method: HookType,
     **kwargs: typing.Any,
-) -> list[typing.Optional[EvaluationContext]]:
+) -> list[EvaluationContext | None]:
     """
     Run multiple hooks of any hook type. All of these hooks will be run through an
     exception check.
@@ -102,7 +102,7 @@ def _execute_hooks_unchecked(
     hooks_and_context: list[tuple[Hook, HookContext]],
     hook_method: HookType,
     **kwargs: typing.Any,
-) -> list[typing.Optional[EvaluationContext]]:
+) -> list[EvaluationContext | None]:
     """
     Execute a single hook without checking whether an exception is thrown. This is
     used in the before and after hooks since any exception will be caught in the
@@ -123,7 +123,7 @@ def _execute_hooks_unchecked(
 
 def _execute_hook_checked(
     hook: Hook, hook_method: HookType, **kwargs: typing.Any
-) -> typing.Optional[EvaluationContext]:
+) -> EvaluationContext | None:
     """
     Try and run a single hook and catch any exception thrown. This is used in the
     after all and error hooks since any error thrown at this point needs to be caught.
@@ -135,7 +135,7 @@ def _execute_hook_checked(
     """
     try:
         return typing.cast(
-            "typing.Optional[EvaluationContext]",
+            "EvaluationContext | None",
             getattr(hook, hook_method.value)(**kwargs),
         )
     except Exception:  # pragma: no cover
diff --git a/openfeature/provider/__init__.py b/openfeature/provider/__init__.py
index cf21c023..aea5069f 100644
--- a/openfeature/provider/__init__.py
+++ b/openfeature/provider/__init__.py
@@ -46,78 +46,74 @@ def resolve_boolean_details(
         self,
         flag_key: str,
         default_value: bool,
-        evaluation_context: typing.Optional[EvaluationContext] = None,
+        evaluation_context: EvaluationContext | None = None,
     ) -> FlagResolutionDetails[bool]: ...
 
     async def resolve_boolean_details_async(
         self,
         flag_key: str,
         default_value: bool,
-        evaluation_context: typing.Optional[EvaluationContext] = None,
+        evaluation_context: EvaluationContext | None = None,
     ) -> FlagResolutionDetails[bool]: ...
 
     def resolve_string_details(
         self,
         flag_key: str,
         default_value: str,
-        evaluation_context: typing.Optional[EvaluationContext] = None,
+        evaluation_context: EvaluationContext | None = None,
     ) -> FlagResolutionDetails[str]: ...
 
     async def resolve_string_details_async(
         self,
         flag_key: str,
         default_value: str,
-        evaluation_context: typing.Optional[EvaluationContext] = None,
+        evaluation_context: EvaluationContext | None = None,
     ) -> FlagResolutionDetails[str]: ...
 
     def resolve_integer_details(
         self,
         flag_key: str,
         default_value: int,
-        evaluation_context: typing.Optional[EvaluationContext] = None,
+        evaluation_context: EvaluationContext | None = None,
     ) -> FlagResolutionDetails[int]: ...
 
     async def resolve_integer_details_async(
         self,
         flag_key: str,
         default_value: int,
-        evaluation_context: typing.Optional[EvaluationContext] = None,
+        evaluation_context: EvaluationContext | None = None,
     ) -> FlagResolutionDetails[int]: ...
 
     def resolve_float_details(
         self,
         flag_key: str,
         default_value: float,
-        evaluation_context: typing.Optional[EvaluationContext] = None,
+        evaluation_context: EvaluationContext | None = None,
     ) -> FlagResolutionDetails[float]: ...
 
     async def resolve_float_details_async(
         self,
         flag_key: str,
         default_value: float,
-        evaluation_context: typing.Optional[EvaluationContext] = None,
+        evaluation_context: EvaluationContext | None = None,
     ) -> FlagResolutionDetails[float]: ...
 
     def resolve_object_details(
         self,
         flag_key: str,
-        default_value: typing.Union[
-            Sequence[FlagValueType], Mapping[str, FlagValueType]
-        ],
-        evaluation_context: typing.Optional[EvaluationContext] = None,
+        default_value: Sequence[FlagValueType] | Mapping[str, FlagValueType],
+        evaluation_context: EvaluationContext | None = None,
     ) -> FlagResolutionDetails[
-        typing.Union[Sequence[FlagValueType], Mapping[str, FlagValueType]]
+        Sequence[FlagValueType] | Mapping[str, FlagValueType]
     ]: ...
 
     async def resolve_object_details_async(
         self,
         flag_key: str,
-        default_value: typing.Union[
-            Sequence[FlagValueType], Mapping[str, FlagValueType]
-        ],
-        evaluation_context: typing.Optional[EvaluationContext] = None,
+        default_value: Sequence[FlagValueType] | Mapping[str, FlagValueType],
+        evaluation_context: EvaluationContext | None = None,
     ) -> FlagResolutionDetails[
-        typing.Union[Sequence[FlagValueType], Mapping[str, FlagValueType]]
+        Sequence[FlagValueType] | Mapping[str, FlagValueType]
     ]: ...
 
 
@@ -154,7 +150,7 @@ def resolve_boolean_details(
         self,
         flag_key: str,
         default_value: bool,
-        evaluation_context: typing.Optional[EvaluationContext] = None,
+        evaluation_context: EvaluationContext | None = None,
     ) -> FlagResolutionDetails[bool]:
         pass
 
@@ -162,7 +158,7 @@ async def resolve_boolean_details_async(
         self,
         flag_key: str,
         default_value: bool,
-        evaluation_context: typing.Optional[EvaluationContext] = None,
+        evaluation_context: EvaluationContext | None = None,
     ) -> FlagResolutionDetails[bool]:
         return self.resolve_boolean_details(flag_key, default_value, evaluation_context)
 
@@ -171,7 +167,7 @@ def resolve_string_details(
         self,
         flag_key: str,
         default_value: str,
-        evaluation_context: typing.Optional[EvaluationContext] = None,
+        evaluation_context: EvaluationContext | None = None,
     ) -> FlagResolutionDetails[str]:
         pass
 
@@ -179,7 +175,7 @@ async def resolve_string_details_async(
         self,
         flag_key: str,
         default_value: str,
-        evaluation_context: typing.Optional[EvaluationContext] = None,
+        evaluation_context: EvaluationContext | None = None,
     ) -> FlagResolutionDetails[str]:
         return self.resolve_string_details(flag_key, default_value, evaluation_context)
 
@@ -188,7 +184,7 @@ def resolve_integer_details(
         self,
         flag_key: str,
         default_value: int,
-        evaluation_context: typing.Optional[EvaluationContext] = None,
+        evaluation_context: EvaluationContext | None = None,
     ) -> FlagResolutionDetails[int]:
         pass
 
@@ -196,7 +192,7 @@ async def resolve_integer_details_async(
         self,
         flag_key: str,
         default_value: int,
-        evaluation_context: typing.Optional[EvaluationContext] = None,
+        evaluation_context: EvaluationContext | None = None,
     ) -> FlagResolutionDetails[int]:
         return self.resolve_integer_details(flag_key, default_value, evaluation_context)
 
@@ -205,7 +201,7 @@ def resolve_float_details(
         self,
         flag_key: str,
         default_value: float,
-        evaluation_context: typing.Optional[EvaluationContext] = None,
+        evaluation_context: EvaluationContext | None = None,
     ) -> FlagResolutionDetails[float]:
         pass
 
@@ -213,7 +209,7 @@ async def resolve_float_details_async(
         self,
         flag_key: str,
         default_value: float,
-        evaluation_context: typing.Optional[EvaluationContext] = None,
+        evaluation_context: EvaluationContext | None = None,
     ) -> FlagResolutionDetails[float]:
         return self.resolve_float_details(flag_key, default_value, evaluation_context)
 
@@ -221,25 +217,17 @@ async def resolve_float_details_async(
     def resolve_object_details(
         self,
         flag_key: str,
-        default_value: typing.Union[
-            Sequence[FlagValueType], Mapping[str, FlagValueType]
-        ],
-        evaluation_context: typing.Optional[EvaluationContext] = None,
-    ) -> FlagResolutionDetails[
-        typing.Union[Sequence[FlagValueType], Mapping[str, FlagValueType]]
-    ]:
+        default_value: Sequence[FlagValueType] | Mapping[str, FlagValueType],
+        evaluation_context: EvaluationContext | None = None,
+    ) -> FlagResolutionDetails[Sequence[FlagValueType] | Mapping[str, FlagValueType]]:
         pass
 
     async def resolve_object_details_async(
         self,
         flag_key: str,
-        default_value: typing.Union[
-            Sequence[FlagValueType], Mapping[str, FlagValueType]
-        ],
-        evaluation_context: typing.Optional[EvaluationContext] = None,
-    ) -> FlagResolutionDetails[
-        typing.Union[Sequence[FlagValueType], Mapping[str, FlagValueType]]
-    ]:
+        default_value: Sequence[FlagValueType] | Mapping[str, FlagValueType],
+        evaluation_context: EvaluationContext | None = None,
+    ) -> FlagResolutionDetails[Sequence[FlagValueType] | Mapping[str, FlagValueType]]:
         return self.resolve_object_details(flag_key, default_value, evaluation_context)
 
     def emit_provider_ready(self, details: ProviderEventDetails) -> None:
diff --git a/openfeature/provider/_registry.py b/openfeature/provider/_registry.py
index 1b5ff041..7529d9fa 100644
--- a/openfeature/provider/_registry.py
+++ b/openfeature/provider/_registry.py
@@ -1,5 +1,3 @@
-import typing
-
 from openfeature._event_support import run_handlers_for_provider
 from openfeature.evaluation_context import EvaluationContext, get_evaluation_context
 from openfeature.event import (
@@ -36,7 +34,7 @@ def set_provider(self, domain: str, provider: FeatureProvider) -> None:
             self._initialize_provider(provider)
         providers[domain] = provider
 
-    def get_provider(self, domain: typing.Optional[str]) -> FeatureProvider:
+    def get_provider(self, domain: str | None) -> FeatureProvider:
         if domain is None:
             return self._default_provider
         return self._providers.get(domain, self._default_provider)
diff --git a/openfeature/provider/in_memory_provider.py b/openfeature/provider/in_memory_provider.py
index 958edd71..2ef00db9 100644
--- a/openfeature/provider/in_memory_provider.py
+++ b/openfeature/provider/in_memory_provider.py
@@ -35,12 +35,13 @@ class State(StrEnum):
     variants: dict[str, T_co]
     flag_metadata: FlagMetadata = field(default_factory=dict)
     state: State = State.ENABLED
-    context_evaluator: typing.Optional[
+    context_evaluator: (
         Callable[[InMemoryFlag[T_co], EvaluationContext], FlagResolutionDetails[T_co]]
-    ] = None
+        | None
+    ) = None
 
     def resolve(
-        self, evaluation_context: typing.Optional[EvaluationContext]
+        self, evaluation_context: EvaluationContext | None
     ) -> FlagResolutionDetails[T_co]:
         if self.context_evaluator:
             return self.context_evaluator(
@@ -76,7 +77,7 @@ def resolve_boolean_details(
         self,
         flag_key: str,
         default_value: bool,
-        evaluation_context: typing.Optional[EvaluationContext] = None,
+        evaluation_context: EvaluationContext | None = None,
     ) -> FlagResolutionDetails[bool]:
         return self._resolve(flag_key, default_value, evaluation_context)
 
@@ -84,7 +85,7 @@ async def resolve_boolean_details_async(
         self,
         flag_key: str,
         default_value: bool,
-        evaluation_context: typing.Optional[EvaluationContext] = None,
+        evaluation_context: EvaluationContext | None = None,
     ) -> FlagResolutionDetails[bool]:
         return await self._resolve_async(flag_key, default_value, evaluation_context)
 
@@ -92,7 +93,7 @@ def resolve_string_details(
         self,
         flag_key: str,
         default_value: str,
-        evaluation_context: typing.Optional[EvaluationContext] = None,
+        evaluation_context: EvaluationContext | None = None,
     ) -> FlagResolutionDetails[str]:
         return self._resolve(flag_key, default_value, evaluation_context)
 
@@ -100,7 +101,7 @@ async def resolve_string_details_async(
         self,
         flag_key: str,
         default_value: str,
-        evaluation_context: typing.Optional[EvaluationContext] = None,
+        evaluation_context: EvaluationContext | None = None,
     ) -> FlagResolutionDetails[str]:
         return await self._resolve_async(flag_key, default_value, evaluation_context)
 
@@ -108,7 +109,7 @@ def resolve_integer_details(
         self,
         flag_key: str,
         default_value: int,
-        evaluation_context: typing.Optional[EvaluationContext] = None,
+        evaluation_context: EvaluationContext | None = None,
     ) -> FlagResolutionDetails[int]:
         return self._resolve(flag_key, default_value, evaluation_context)
 
@@ -116,7 +117,7 @@ async def resolve_integer_details_async(
         self,
         flag_key: str,
         default_value: int,
-        evaluation_context: typing.Optional[EvaluationContext] = None,
+        evaluation_context: EvaluationContext | None = None,
     ) -> FlagResolutionDetails[int]:
         return await self._resolve_async(flag_key, default_value, evaluation_context)
 
@@ -124,7 +125,7 @@ def resolve_float_details(
         self,
         flag_key: str,
         default_value: float,
-        evaluation_context: typing.Optional[EvaluationContext] = None,
+        evaluation_context: EvaluationContext | None = None,
     ) -> FlagResolutionDetails[float]:
         return self._resolve(flag_key, default_value, evaluation_context)
 
@@ -132,39 +133,31 @@ async def resolve_float_details_async(
         self,
         flag_key: str,
         default_value: float,
-        evaluation_context: typing.Optional[EvaluationContext] = None,
+        evaluation_context: EvaluationContext | None = None,
     ) -> FlagResolutionDetails[float]:
         return await self._resolve_async(flag_key, default_value, evaluation_context)
 
     def resolve_object_details(
         self,
         flag_key: str,
-        default_value: typing.Union[
-            Sequence[FlagValueType], Mapping[str, FlagValueType]
-        ],
-        evaluation_context: typing.Optional[EvaluationContext] = None,
-    ) -> FlagResolutionDetails[
-        typing.Union[Sequence[FlagValueType], Mapping[str, FlagValueType]]
-    ]:
+        default_value: Sequence[FlagValueType] | Mapping[str, FlagValueType],
+        evaluation_context: EvaluationContext | None = None,
+    ) -> FlagResolutionDetails[Sequence[FlagValueType] | Mapping[str, FlagValueType]]:
         return self._resolve(flag_key, default_value, evaluation_context)
 
     async def resolve_object_details_async(
         self,
         flag_key: str,
-        default_value: typing.Union[
-            Sequence[FlagValueType], Mapping[str, FlagValueType]
-        ],
-        evaluation_context: typing.Optional[EvaluationContext] = None,
-    ) -> FlagResolutionDetails[
-        typing.Union[Sequence[FlagValueType], Mapping[str, FlagValueType]]
-    ]:
+        default_value: Sequence[FlagValueType] | Mapping[str, FlagValueType],
+        evaluation_context: EvaluationContext | None = None,
+    ) -> FlagResolutionDetails[Sequence[FlagValueType] | Mapping[str, FlagValueType]]:
         return await self._resolve_async(flag_key, default_value, evaluation_context)
 
     def _resolve(
         self,
         flag_key: str,
         default_value: V,
-        evaluation_context: typing.Optional[EvaluationContext],
+        evaluation_context: EvaluationContext | None,
     ) -> FlagResolutionDetails[V]:
         flag = self._flags.get(flag_key)
         if flag is None:
@@ -180,6 +173,6 @@ async def _resolve_async(
         self,
         flag_key: str,
         default_value: V,
-        evaluation_context: typing.Optional[EvaluationContext],
+        evaluation_context: EvaluationContext | None,
     ) -> FlagResolutionDetails[V]:
         return self._resolve(flag_key, default_value, evaluation_context)
diff --git a/openfeature/provider/no_op_provider.py b/openfeature/provider/no_op_provider.py
index 30d4c571..9bd1d169 100644
--- a/openfeature/provider/no_op_provider.py
+++ b/openfeature/provider/no_op_provider.py
@@ -27,7 +27,7 @@ def resolve_boolean_details(
         self,
         flag_key: str,
         default_value: bool,
-        evaluation_context: typing.Optional[EvaluationContext] = None,
+        evaluation_context: EvaluationContext | None = None,
     ) -> FlagResolutionDetails[bool]:
         return FlagResolutionDetails(
             value=default_value,
@@ -39,7 +39,7 @@ def resolve_string_details(
         self,
         flag_key: str,
         default_value: str,
-        evaluation_context: typing.Optional[EvaluationContext] = None,
+        evaluation_context: EvaluationContext | None = None,
     ) -> FlagResolutionDetails[str]:
         return FlagResolutionDetails(
             value=default_value,
@@ -51,7 +51,7 @@ def resolve_integer_details(
         self,
         flag_key: str,
         default_value: int,
-        evaluation_context: typing.Optional[EvaluationContext] = None,
+        evaluation_context: EvaluationContext | None = None,
     ) -> FlagResolutionDetails[int]:
         return FlagResolutionDetails(
             value=default_value,
@@ -63,7 +63,7 @@ def resolve_float_details(
         self,
         flag_key: str,
         default_value: float,
-        evaluation_context: typing.Optional[EvaluationContext] = None,
+        evaluation_context: EvaluationContext | None = None,
     ) -> FlagResolutionDetails[float]:
         return FlagResolutionDetails(
             value=default_value,
@@ -74,13 +74,9 @@ def resolve_float_details(
     def resolve_object_details(
         self,
         flag_key: str,
-        default_value: typing.Union[
-            Sequence[FlagValueType], Mapping[str, FlagValueType]
-        ],
-        evaluation_context: typing.Optional[EvaluationContext] = None,
-    ) -> FlagResolutionDetails[
-        typing.Union[Sequence[FlagValueType], Mapping[str, FlagValueType]]
-    ]:
+        default_value: Sequence[FlagValueType] | Mapping[str, FlagValueType],
+        evaluation_context: EvaluationContext | None = None,
+    ) -> FlagResolutionDetails[Sequence[FlagValueType] | Mapping[str, FlagValueType]]:
         return FlagResolutionDetails(
             value=default_value,
             reason=Reason.DEFAULT,
diff --git a/openfeature/telemetry/__init__.py b/openfeature/telemetry/__init__.py
index ef97eff3..7342bb81 100644
--- a/openfeature/telemetry/__init__.py
+++ b/openfeature/telemetry/__init__.py
@@ -25,7 +25,7 @@
 @dataclass
 class EvaluationEvent(typing.Generic[T_co]):
     name: str
-    attributes: Mapping[TelemetryAttribute, typing.Union[str, T_co]]
+    attributes: Mapping[TelemetryAttribute, str | T_co]
     body: Mapping[TelemetryBodyField, T_co]
 
 
diff --git a/openfeature/transaction_context/context_var_transaction_context_propagator.py b/openfeature/transaction_context/context_var_transaction_context_propagator.py
index 30869359..449c67a1 100644
--- a/openfeature/transaction_context/context_var_transaction_context_propagator.py
+++ b/openfeature/transaction_context/context_var_transaction_context_propagator.py
@@ -1,4 +1,3 @@
-import typing
 from contextvars import ContextVar
 
 from openfeature.evaluation_context import EvaluationContext
@@ -8,8 +7,8 @@
 
 
 class ContextVarsTransactionContextPropagator(TransactionContextPropagator):
-    _transaction_context_var: ContextVar[typing.Optional[EvaluationContext]] = (
-        ContextVar("transaction_context", default=None)
+    _transaction_context_var: ContextVar[EvaluationContext | None] = ContextVar(
+        "transaction_context", default=None
     )
 
     def get_transaction_context(self) -> EvaluationContext:
diff --git a/pyproject.toml b/pyproject.toml
index 79c398e2..bd2e00dc 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -71,9 +71,10 @@ exclude = [
     ".git",
     ".venv",
     "__pycache__",
+    "spec",
     "venv",
 ]
-target-version = "py39"
+target-version = "py310"
 
 [tool.ruff.lint]
 select = [
@@ -139,4 +140,4 @@ test-cov = "scripts.scripts:test_cov"
 cov-report = "scripts.scripts:cov_report"
 cov = "scripts.scripts:cov"
 e2e = "scripts.scripts:e2e"
-precommit = "scripts.scripts:precommit"
\ No newline at end of file
+precommit = "scripts.scripts:precommit"
diff --git a/tests/hook/test_hook_data.py b/tests/hook/test_hook_data.py
index 33d12591..a7e3e0d3 100644
--- a/tests/hook/test_hook_data.py
+++ b/tests/hook/test_hook_data.py
@@ -20,7 +20,7 @@ def __init__(self, data: dict[str, typing.Any]):
 
     def before(
         self, hook_context: HookContext, hints: HookHints
-    ) -> typing.Optional[EvaluationContext]:
+    ) -> EvaluationContext | None:
         hook_context.hook_data = hook_context.hook_data | self.data_before
         return None
 
diff --git a/tests/provider/test_provider_compatibility.py b/tests/provider/test_provider_compatibility.py
index b49c6553..80c8cf2a 100644
--- a/tests/provider/test_provider_compatibility.py
+++ b/tests/provider/test_provider_compatibility.py
@@ -1,5 +1,3 @@
-import typing
-
 import pytest
 
 from openfeature.api import get_client, set_provider
@@ -19,7 +17,7 @@ def resolve_boolean_details(
         self,
         flag_key: str,
         default_value: bool,
-        evaluation_context: typing.Optional[EvaluationContext] = None,
+        evaluation_context: EvaluationContext | None = None,
     ) -> FlagResolutionDetails[bool]:
         return FlagResolutionDetails(value=True)
 
@@ -27,7 +25,7 @@ def resolve_string_details(
         self,
         flag_key: str,
         default_value: str,
-        evaluation_context: typing.Optional[EvaluationContext] = None,
+        evaluation_context: EvaluationContext | None = None,
     ) -> FlagResolutionDetails[str]:
         return FlagResolutionDetails(value="string")
 
@@ -35,7 +33,7 @@ def resolve_integer_details(
         self,
         flag_key: str,
         default_value: int,
-        evaluation_context: typing.Optional[EvaluationContext] = None,
+        evaluation_context: EvaluationContext | None = None,
     ) -> FlagResolutionDetails[int]:
         return FlagResolutionDetails(value=1)
 
@@ -43,16 +41,16 @@ def resolve_float_details(
         self,
         flag_key: str,
         default_value: float,
-        evaluation_context: typing.Optional[EvaluationContext] = None,
+        evaluation_context: EvaluationContext | None = None,
     ) -> FlagResolutionDetails[float]:
         return FlagResolutionDetails(value=10.0)
 
     def resolve_object_details(
         self,
         flag_key: str,
-        default_value: typing.Union[dict, list],
-        evaluation_context: typing.Optional[EvaluationContext] = None,
-    ) -> FlagResolutionDetails[typing.Union[dict, list]]:
+        default_value: dict | list,
+        evaluation_context: EvaluationContext | None = None,
+    ) -> FlagResolutionDetails[dict | list]:
         return FlagResolutionDetails(value={"key": "value"})
 
 
@@ -92,7 +90,7 @@ async def resolve_boolean_details_async(
             self,
             flag_key: str,
             default_value: bool,
-            evaluation_context: typing.Optional[EvaluationContext] = None,
+            evaluation_context: EvaluationContext | None = None,
         ) -> FlagResolutionDetails[bool]:
             return FlagResolutionDetails(value=False)
 
@@ -116,7 +114,7 @@ async def resolve_boolean_details_async(
             self,
             flag_key: str,
             default_value: bool,
-            evaluation_context: typing.Optional[EvaluationContext] = None,
+            evaluation_context: EvaluationContext | None = None,
         ) -> FlagResolutionDetails[bool]:
             return FlagResolutionDetails(value=True)
 
@@ -144,7 +142,7 @@ async def resolve_boolean_details_async(
             self,
             flag_key: str,
             default_value: bool,
-            evaluation_context: typing.Optional[EvaluationContext] = None,
+            evaluation_context: EvaluationContext | None = None,
         ) -> FlagResolutionDetails[bool]:
             return FlagResolutionDetails(value=True)
 
@@ -152,7 +150,7 @@ def resolve_boolean_details(
             self,
             flag_key: str,
             default_value: bool,
-            evaluation_context: typing.Optional[EvaluationContext] = None,
+            evaluation_context: EvaluationContext | None = None,
         ) -> FlagResolutionDetails[bool]:
             raise NotImplementedError("Use the async method")
 
@@ -160,7 +158,7 @@ def resolve_string_details(
             self,
             flag_key: str,
             default_value: str,
-            evaluation_context: typing.Optional[EvaluationContext] = None,
+            evaluation_context: EvaluationContext | None = None,
         ) -> FlagResolutionDetails[str]:
             raise NotImplementedError("Use the async method")
 
@@ -168,7 +166,7 @@ def resolve_integer_details(
             self,
             flag_key: str,
             default_value: int,
-            evaluation_context: typing.Optional[EvaluationContext] = None,
+            evaluation_context: EvaluationContext | None = None,
         ) -> FlagResolutionDetails[int]:
             raise NotImplementedError("Use the async method")
 
@@ -176,16 +174,16 @@ def resolve_float_details(
             self,
             flag_key: str,
             default_value: float,
-            evaluation_context: typing.Optional[EvaluationContext] = None,
+            evaluation_context: EvaluationContext | None = None,
         ) -> FlagResolutionDetails[float]:
             raise NotImplementedError("Use the async method")
 
         def resolve_object_details(
             self,
             flag_key: str,
-            default_value: typing.Union[dict, list],
-            evaluation_context: typing.Optional[EvaluationContext] = None,
-        ) -> FlagResolutionDetails[typing.Union[dict, list]]:
+            default_value: dict | list,
+            evaluation_context: EvaluationContext | None = None,
+        ) -> FlagResolutionDetails[dict | list]:
             raise NotImplementedError("Use the async method")
 
     # When