diff --git a/pyproject.toml b/pyproject.toml
index e3c73d5cd..95895ba5a 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -238,6 +238,7 @@ types-requests = "requests"
 [tool.deptry.per_rule_ignores]
 DEP002 = [
     # Deprecated dependencies
+    "pendulum",
     "python-dateutil",
     # Transitive constraints
     "numpy",
@@ -407,6 +408,9 @@ typing = "t"
 fixture-parentheses = false
 parametrize-names-type = "csv"
 
+[tool.ruff.lint.flake8-tidy-imports.banned-api]
+"pendulum".msg = "BAN002: pendulum is banned"
+
 [tool.ruff.lint.isort]
 known-first-party = ["singer_sdk", "samples", "tests"]
 required-imports = ["from __future__ import annotations"]
diff --git a/singer_sdk/authenticators.py b/singer_sdk/authenticators.py
index 8c550fe31..09f42efee 100644
--- a/singer_sdk/authenticators.py
+++ b/singer_sdk/authenticators.py
@@ -7,7 +7,6 @@
 import math
 import typing as t
 import warnings
-from datetime import timedelta
 from types import MappingProxyType
 from urllib.parse import parse_qs, urlencode, urlsplit, urlunsplit
 
@@ -557,7 +556,7 @@ def oauth_request_body(self) -> dict:
             "iss": self.client_id,
             "scope": self.oauth_scopes,
             "aud": self.auth_endpoint,
-            "exp": math.floor((request_time + timedelta(hours=1)).timestamp()),
+            "exp": math.floor((request_time + datetime.timedelta(hours=1)).timestamp()),
             "iat": math.floor(request_time.timestamp()),
         }
 
diff --git a/singer_sdk/helpers/_util.py b/singer_sdk/helpers/_util.py
index 5d8f53f26..0e8250c2a 100644
--- a/singer_sdk/helpers/_util.py
+++ b/singer_sdk/helpers/_util.py
@@ -2,15 +2,11 @@
 
 from __future__ import annotations
 
+import datetime
 import json
 import typing as t
 from pathlib import Path, PurePath
 
-import pendulum
-
-if t.TYPE_CHECKING:
-    import datetime
-
 
 def read_json_file(path: PurePath | str) -> dict[str, t.Any]:
     """Read json file, throwing an error if missing."""
@@ -30,5 +26,4 @@ def read_json_file(path: PurePath | str) -> dict[str, t.Any]:
 
 def utc_now() -> datetime.datetime:
     """Return current time in UTC."""
-    # TODO: replace with datetime.datetime.now(tz=datetime.timezone.utc)
-    return pendulum.now(tz="UTC")
+    return datetime.datetime.now(datetime.timezone.utc)
diff --git a/singer_sdk/streams/core.py b/singer_sdk/streams/core.py
index 886466c5d..0b4d6eef6 100644
--- a/singer_sdk/streams/core.py
+++ b/singer_sdk/streams/core.py
@@ -12,8 +12,6 @@
 from pathlib import Path
 from types import MappingProxyType
 
-import pendulum
-
 import singer_sdk._singerlib as singer
 from singer_sdk import metrics
 from singer_sdk.batch import Batcher
@@ -30,6 +28,7 @@
     SDKBatchMessage,
 )
 from singer_sdk.helpers._catalog import pop_deselected_record_properties
+from singer_sdk.helpers._compat import datetime_fromisoformat
 from singer_sdk.helpers._flattening import get_flattening_options
 from singer_sdk.helpers._state import (
     finalize_state_progress_markers,
@@ -291,7 +290,8 @@ def get_starting_timestamp(
             msg = f"The replication key {self.replication_key} is not of timestamp type"
             raise ValueError(msg)
 
-        return t.cast(datetime.datetime, pendulum.parse(value))
+        result = datetime_fromisoformat(value)
+        return result if result.tzinfo else result.replace(tzinfo=datetime.timezone.utc)
 
     @property
     def selected(self) -> bool:
@@ -377,7 +377,7 @@ def compare_start_date(self, value: str, start_date_value: str) -> str:
             The most recent value between the bookmark and start date.
         """
         if self.is_timestamp_replication_key:
-            return max(value, start_date_value, key=pendulum.parse)
+            return max(value, start_date_value, key=datetime_fromisoformat)
 
         return value
 
diff --git a/tests/core/conftest.py b/tests/core/conftest.py
index 97eb76e7f..30798b01c 100644
--- a/tests/core/conftest.py
+++ b/tests/core/conftest.py
@@ -5,11 +5,11 @@
 import typing as t
 from contextlib import contextmanager
 
-import pendulum
 import pytest
 from typing_extensions import override
 
 from singer_sdk import Stream, Tap
+from singer_sdk.helpers._compat import datetime_fromisoformat
 from singer_sdk.typing import (
     DateTimeType,
     IntegerType,
@@ -70,7 +70,7 @@ class UnixTimestampIncrementalStream2(UnixTimestampIncrementalStream):
     def compare_start_date(self, value: str, start_date_value: str) -> str:
         """Compare a value to a start date value."""
 
-        start_timestamp = pendulum.parse(start_date_value).format("X")
+        start_timestamp = datetime_fromisoformat(start_date_value).timestamp()
         return max(value, start_timestamp, key=float)
 
 
diff --git a/tests/core/test_streams.py b/tests/core/test_streams.py
index 2dd0dd4cb..592f921e6 100644
--- a/tests/core/test_streams.py
+++ b/tests/core/test_streams.py
@@ -6,7 +6,6 @@
 import logging
 import typing as t
 
-import pendulum
 import pytest
 import requests
 
@@ -24,12 +23,12 @@
 from singer_sdk.typing import IntegerType, PropertiesList, Property, StringType
 from tests.core.conftest import SimpleTestStream
 
-CONFIG_START_DATE = "2021-01-01"
-
 if t.TYPE_CHECKING:
     from singer_sdk import Stream, Tap
     from tests.core.conftest import SimpleTestTap
 
+CONFIG_START_DATE = "2021-01-01"
+
 
 class RestTestStream(RESTStream):
     """Test RESTful stream class."""
@@ -181,7 +180,7 @@ def test_stream_apply_catalog(stream: Stream):
             "unix_ts_override",
             None,
             "1577858400",
-            pendulum.parse(CONFIG_START_DATE).format("X"),
+            parse(CONFIG_START_DATE).timestamp(),
             id="unix-ts-repl-key-old-bookmark",
         ),
     ],