diff --git a/singer_sdk/_singerlib/messages.py b/singer_sdk/_singerlib/messages.py
index 4f45acb69..2131290b6 100644
--- a/singer_sdk/_singerlib/messages.py
+++ b/singer_sdk/_singerlib/messages.py
@@ -8,7 +8,7 @@
 from dataclasses import asdict, dataclass, field
 from datetime import datetime, timezone
 
-from singer_sdk.helpers._util import serialize_json
+from singer_sdk._singerlib.serde import serialize_json
 
 if sys.version_info < (3, 11):
     from backports.datetime_fromisoformat import MonkeyPatch
diff --git a/singer_sdk/_singerlib/serde.py b/singer_sdk/_singerlib/serde.py
new file mode 100644
index 000000000..cd0cfce2e
--- /dev/null
+++ b/singer_sdk/_singerlib/serde.py
@@ -0,0 +1,66 @@
+from __future__ import annotations
+
+import datetime
+import decimal
+import json
+import logging
+import typing as t
+
+import simplejson
+
+logger = logging.getLogger(__name__)
+
+
+def _default_encoding(obj: t.Any) -> str:  # noqa: ANN401
+    """Default JSON encoder.
+
+    Args:
+        obj: The object to encode.
+
+    Returns:
+        The encoded object.
+    """
+    return obj.isoformat(sep="T") if isinstance(obj, datetime.datetime) else str(obj)
+
+
+def deserialize_json(json_str: str, **kwargs: t.Any) -> dict:
+    """Deserialize a line of json.
+
+    Args:
+        json_str: A single line of json.
+        **kwargs: Optional key word arguments.
+
+    Returns:
+        A dictionary of the deserialized json.
+
+    Raises:
+        json.decoder.JSONDecodeError: raised if any lines are not valid json
+    """
+    try:
+        return json.loads(  # type: ignore[no-any-return]
+            json_str,
+            parse_float=decimal.Decimal,
+            **kwargs,
+        )
+    except json.decoder.JSONDecodeError as exc:
+        logger.exception("Unable to parse:\n%s", json_str, exc_info=exc)
+        raise
+
+
+def serialize_json(obj: object, **kwargs: t.Any) -> str:
+    """Serialize a dictionary into a line of json.
+
+    Args:
+        obj: A Python object usually a dict.
+        **kwargs: Optional key word arguments.
+
+    Returns:
+        A string of serialized json.
+    """
+    return simplejson.dumps(
+        obj,
+        use_decimal=True,
+        default=_default_encoding,
+        separators=(",", ":"),
+        **kwargs,
+    )
diff --git a/singer_sdk/connectors/sql.py b/singer_sdk/connectors/sql.py
index 652246e06..0a9a2f90a 100644
--- a/singer_sdk/connectors/sql.py
+++ b/singer_sdk/connectors/sql.py
@@ -12,14 +12,8 @@
 import sqlalchemy as sa
 
 from singer_sdk import typing as th
-from singer_sdk._singerlib import CatalogEntry, MetadataMapping, Schema
+from singer_sdk._singerlib import CatalogEntry, MetadataMapping, Schema, serde
 from singer_sdk.exceptions import ConfigValidationError
-from singer_sdk.helpers._util import (
-    deserialize_json as util_deserialize_json,
-)
-from singer_sdk.helpers._util import (
-    serialize_json as util_serialize_json,
-)
 from singer_sdk.helpers.capabilities import TargetLoadMethods
 
 if t.TYPE_CHECKING:
@@ -1170,7 +1164,7 @@ def serialize_json(self, obj: object) -> str:  # noqa: PLR6301
 
         .. versionadded:: 0.31.0
         """
-        return util_serialize_json(obj)
+        return serde.serialize_json(obj)
 
     def deserialize_json(self, json_str: str) -> object:  # noqa: PLR6301
         """Deserialize a JSON string to an object.
@@ -1186,7 +1180,7 @@ def deserialize_json(self, json_str: str) -> object:  # noqa: PLR6301
 
         .. versionadded:: 0.31.0
         """
-        return util_deserialize_json(json_str)
+        return serde.deserialize_json(json_str)
 
     def delete_old_versions(
         self,
diff --git a/singer_sdk/contrib/batch_encoder_jsonl.py b/singer_sdk/contrib/batch_encoder_jsonl.py
index 262b840df..7c9505de4 100644
--- a/singer_sdk/contrib/batch_encoder_jsonl.py
+++ b/singer_sdk/contrib/batch_encoder_jsonl.py
@@ -6,8 +6,8 @@
 import typing as t
 from uuid import uuid4
 
+from singer_sdk._singerlib.serde import serialize_json
 from singer_sdk.batch import BaseBatcher, lazy_chunked_generator
-from singer_sdk.helpers._util import serialize_json
 
 __all__ = ["JSONLinesBatcher"]
 
diff --git a/singer_sdk/helpers/_flattening.py b/singer_sdk/helpers/_flattening.py
index edd262f98..c1999fcc6 100644
--- a/singer_sdk/helpers/_flattening.py
+++ b/singer_sdk/helpers/_flattening.py
@@ -10,7 +10,7 @@
 
 import inflection
 
-from singer_sdk.helpers._util import serialize_json
+from singer_sdk._singerlib.serde import serialize_json
 
 DEFAULT_FLATTENING_SEPARATOR = "__"
 
diff --git a/singer_sdk/helpers/_util.py b/singer_sdk/helpers/_util.py
index 5f301fa16..0e8250c2a 100644
--- a/singer_sdk/helpers/_util.py
+++ b/singer_sdk/helpers/_util.py
@@ -3,78 +3,10 @@
 from __future__ import annotations
 
 import datetime
-import decimal
 import json
-import logging
-import sys
 import typing as t
 from pathlib import Path, PurePath
 
-import simplejson
-
-if sys.version_info < (3, 11):
-    from backports.datetime_fromisoformat import MonkeyPatch
-
-    MonkeyPatch.patch_fromisoformat()
-
-
-logger = logging.getLogger(__name__)
-
-
-def _default_encoding(obj: t.Any) -> str:  # noqa: ANN401
-    """Default JSON encoder.
-
-    Args:
-        obj: The object to encode.
-
-    Returns:
-        The encoded object.
-    """
-    return obj.isoformat(sep="T") if isinstance(obj, datetime.datetime) else str(obj)
-
-
-def deserialize_json(json_str: str, **kwargs: t.Any) -> dict:
-    """Deserialize a line of json.
-
-    Args:
-        json_str: A single line of json.
-        **kwargs: Optional key word arguments.
-
-    Returns:
-        A dictionary of the deserialized json.
-
-    Raises:
-        json.decoder.JSONDecodeError: raised if any lines are not valid json
-    """
-    try:
-        return json.loads(  # type: ignore[no-any-return]
-            json_str,
-            parse_float=decimal.Decimal,
-            **kwargs,
-        )
-    except json.decoder.JSONDecodeError as exc:
-        logger.exception("Unable to parse:\n%s", json_str, exc_info=exc)
-        raise
-
-
-def serialize_json(obj: object, **kwargs: t.Any) -> str:
-    """Serialize a dictionary into a line of json.
-
-    Args:
-        obj: A Python object usually a dict.
-        **kwargs: Optional key word arguments.
-
-    Returns:
-        A string of serialized json.
-    """
-    return simplejson.dumps(
-        obj,
-        use_decimal=True,
-        default=_default_encoding,
-        separators=(",", ":"),
-        **kwargs,
-    )
-
 
 def read_json_file(path: PurePath | str) -> dict[str, t.Any]:
     """Read json file, throwing an error if missing."""
@@ -89,7 +21,7 @@ def read_json_file(path: PurePath | str) -> dict[str, t.Any]:
                 msg += f"\nFor more info, please see the sample template at: {template}"
         raise FileExistsError(msg)
 
-    return deserialize_json(Path(path).read_text(encoding="utf-8"))
+    return t.cast(dict, json.loads(Path(path).read_text(encoding="utf-8")))
 
 
 def utc_now() -> datetime.datetime:
diff --git a/singer_sdk/io_base.py b/singer_sdk/io_base.py
index 33e045f61..f0abc568b 100644
--- a/singer_sdk/io_base.py
+++ b/singer_sdk/io_base.py
@@ -11,8 +11,8 @@
 from singer_sdk._singerlib.messages import Message, SingerMessageType
 from singer_sdk._singerlib.messages import format_message as singer_format_message
 from singer_sdk._singerlib.messages import write_message as singer_write_message
+from singer_sdk._singerlib.serde import deserialize_json
 from singer_sdk.exceptions import InvalidInputLine
-from singer_sdk.helpers._util import deserialize_json
 
 logger = logging.getLogger(__name__)
 
diff --git a/singer_sdk/sinks/core.py b/singer_sdk/sinks/core.py
index 44dacc5cd..4fb475f8b 100644
--- a/singer_sdk/sinks/core.py
+++ b/singer_sdk/sinks/core.py
@@ -16,6 +16,7 @@
 import jsonschema
 from typing_extensions import override
 
+from singer_sdk._singerlib.serde import deserialize_json
 from singer_sdk.exceptions import (
     InvalidJSONSchema,
     InvalidRecord,
@@ -37,7 +38,6 @@
     get_datelike_property_type,
     handle_invalid_timestamp_in_record,
 )
-from singer_sdk.helpers._util import deserialize_json
 
 if t.TYPE_CHECKING:
     from logging import Logger
diff --git a/singer_sdk/tap_base.py b/singer_sdk/tap_base.py
index 256ad90e3..89076b6f1 100644
--- a/singer_sdk/tap_base.py
+++ b/singer_sdk/tap_base.py
@@ -10,6 +10,7 @@
 import click
 
 from singer_sdk._singerlib import Catalog, StateMessage
+from singer_sdk._singerlib.serde import serialize_json
 from singer_sdk.configuration._dict_config import merge_missing_config_jsonschema
 from singer_sdk.exceptions import (
     AbortedSyncFailedException,
@@ -19,7 +20,7 @@
 from singer_sdk.helpers import _state
 from singer_sdk.helpers._classproperty import classproperty
 from singer_sdk.helpers._state import write_stream_state
-from singer_sdk.helpers._util import read_json_file, serialize_json
+from singer_sdk.helpers._util import read_json_file
 from singer_sdk.helpers.capabilities import (
     BATCH_CONFIG,
     CapabilitiesEnum,
diff --git a/tests/core/test_io.py b/tests/core/test_io.py
index ecc52fac1..9ec9532f2 100644
--- a/tests/core/test_io.py
+++ b/tests/core/test_io.py
@@ -10,7 +10,7 @@
 import pytest
 
 from singer_sdk._singerlib import RecordMessage
-from singer_sdk.helpers._util import deserialize_json
+from singer_sdk._singerlib.serde import deserialize_json
 from singer_sdk.io_base import SingerReader, SingerWriter