diff --git a/CHANGELOG.md b/CHANGELOG.md
index 56e58e9..874a59f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,8 @@
+# Changelog
 
+## 0.2.1
 
+- Add `codecs.jsonencode`
 
 ## 0.2.0
 
diff --git a/src/suou/__init__.py b/src/suou/__init__.py
index 8b663a4..1848eef 100644
--- a/src/suou/__init__.py
+++ b/src/suou/__init__.py
@@ -17,7 +17,7 @@ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 """
 
 from .iding import Siq, SiqCache, SiqType, SiqGen
-from .codecs import StringCase, cb32encode, cb32decode
+from .codecs import StringCase, cb32encode, cb32decode, jsonencode
 from .bits import count_ones, mask_shift
 from .configparse import MissingConfigError, MissingConfigWarning, ConfigOptions, ConfigParserConfigSource, ConfigSource, DictConfigSource, ConfigValue, EnvConfigSource
 from .functools import deprecated, not_implemented
@@ -25,11 +25,11 @@ from .classtools import Wanted, Incomplete
 from .itertools import makelist, kwargs_prefix
 from .i18n import I18n, JsonI18n, TomlI18n
 
-__version__ = "0.2.0"
+__version__ = "0.2.1"
 
 __all__ = (
     'Siq', 'SiqCache', 'SiqType', 'SiqGen', 'StringCase',
     'MissingConfigError', 'MissingConfigWarning', 'ConfigOptions', 'ConfigParserConfigSource', 'ConfigSource', 'ConfigValue', 'EnvConfigSource', 'DictConfigSource',
-    'deprecated', 'not_implemented', 'Wanted', 'Incomplete',
+    'deprecated', 'not_implemented', 'Wanted', 'Incomplete', 'jsonencode'
     'makelist', 'kwargs_prefix', 'I18n', 'JsonI18n', 'TomlI18n', 'cb32encode', 'cb32decode', 'count_ones', 'mask_shift'
 )
diff --git a/src/suou/codecs.py b/src/suou/codecs.py
index 5412875..537780b 100644
--- a/src/suou/codecs.py
+++ b/src/suou/codecs.py
@@ -15,8 +15,11 @@ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 """
 
 import base64
+import datetime
 import enum
+import json
 import re
+from typing import Any, Callable
 
 from suou.functools import not_implemented
 
@@ -74,6 +77,22 @@ def b64decode(val: bytes | str) -> bytes:
         val = val.encode('ascii')
     return base64.urlsafe_b64decode(val.replace(b'/', b'_').replace(b'+', b'-') + b'=' * ((4 - len(val) % 4) % 4))
 
+def _json_default(func = None) -> Callable[Any, str | list | dict]:
+    def default_converter(obj: Any) -> str | list | dict:
+        if isinstance(obj, (datetime.datetime, datetime.date)):
+            return obj.isoformat()
+        elif callable(func):
+            return func(obj)
+        else:
+            raise TypeError
+    return default_converter
+
+def jsonencode(obj: dict, *, skipkeys: bool = True, separators: tuple[str, str] = (',', ':'), default: Callable | None = None, **kwargs) -> str:
+    '''
+    JSON encoder with stricter and smarter defaults.
+    '''
+    return json.dumps(obj, skipkeys=skipkeys, separators=separators, default=_json_default(default), **kwargs)
+
 class StringCase(enum.Enum):
     """
     Enum values used by regex validators and storage converters.
@@ -108,6 +127,6 @@ class StringCase(enum.Enum):
         
 
 __all__ = (
-    'cb32encode', 'cb32decode', 'b32lencode', 'b32ldecode', 'b64encode', 'b64decode',
+    'cb32encode', 'cb32decode', 'b32lencode', 'b32ldecode', 'b64encode', 'b64decode', 'jsonencode'
     'StringCase'
 )
\ No newline at end of file