diff --git a/Lib/collections/__init__.py b/Lib/collections/__init__.py
index 8408255..6842e7a 100644
--- a/Lib/collections/__init__.py
+++ b/Lib/collections/__init__.py
@@ -954,6 +954,9 @@ class ChainMap(MutableMapping):
         'Clear maps[0], leaving maps[1:] intact.'
         self.maps[0].clear()
 
+    def __json__(self):
+        return OrderedDict(self)
+
 
 ################################################################################
 ### UserDict
@@ -1020,6 +1023,9 @@ class UserDict(MutableMapping):
             d[key] = value
         return d
 
+    def __json__(self):
+        return self.data
+
 
 
 ################################################################################
@@ -1093,6 +1099,9 @@ class UserList(MutableSequence):
         else:
             self.data.extend(other)
 
+    def __json__(self):
+        return self.data
+
 
 
 ################################################################################
@@ -1243,3 +1252,6 @@ class UserString(Sequence):
         return self.__class__(self.data.translate(*args))
     def upper(self): return self.__class__(self.data.upper())
     def zfill(self, width): return self.__class__(self.data.zfill(width))
+
+    def __json__(self):
+        return self.data
diff --git a/Lib/json/__init__.py b/Lib/json/__init__.py
index b8d5e6c..5d585a1 100644
--- a/Lib/json/__init__.py
+++ b/Lib/json/__init__.py
@@ -99,12 +99,13 @@ __version__ = '2.0.9'
 __all__ = [
     'dump', 'dumps', 'load', 'loads',
     'JSONDecoder', 'JSONDecodeError', 'JSONEncoder',
+    'register',
 ]
 
 __author__ = 'Bob Ippolito <bob@redivi.com>'
 
 from .decoder import JSONDecoder, JSONDecodeError
-from .encoder import JSONEncoder
+from .encoder import JSONEncoder, dispatch_table
 import codecs
 
 _default_encoder = JSONEncoder(
@@ -365,3 +366,7 @@ def loads(s, *, encoding=None, cls=None, object_hook=None, parse_float=None,
     if parse_constant is not None:
         kw['parse_constant'] = parse_constant
     return cls(**kw).decode(s)
+
+
+def register(cls, func):
+    dispatch_table[cls] = func
diff --git a/Lib/json/encoder.py b/Lib/json/encoder.py
index 41a497c..f37e103 100644
--- a/Lib/json/encoder.py
+++ b/Lib/json/encoder.py
@@ -33,6 +33,8 @@ for i in range(0x20):
 
 INFINITY = float('inf')
 
+dispatch_table = {}
+
 def py_encode_basestring(s):
     """Return a JSON representation of a Python string
 
@@ -176,8 +178,17 @@ class JSONEncoder(object):
                 return JSONEncoder.default(self, o)
 
         """
+        cls = type(o)
+        asjson = getattr(self, 'dispatch_table', dispatch_table).get(cls)
+        #print(id(dispatch_table))
+        #print(getattr(self, 'dispatch_table', dispatch_table))
+        if asjson is not None:
+            return asjson(o)
+        asjson = getattr(o, '__json__', None)
+        if asjson is not None:
+            return asjson()
         raise TypeError("Object of type '%s' is not JSON serializable" %
-                        o.__class__.__name__)
+                        cls.__name__)
 
     def encode(self, o):
         """Return a JSON string representation of a Python data structure.
@@ -428,6 +439,8 @@ def _make_iterencode(markers, _default, _encoder, _indent, _floatstr,
             yield from _iterencode_list(o, _current_indent_level)
         elif isinstance(o, dict):
             yield from _iterencode_dict(o, _current_indent_level)
+        elif isinstance(o, JSONRepr):
+            yield str(o)
         else:
             if markers is not None:
                 markerid = id(o)
@@ -439,3 +452,16 @@ def _make_iterencode(markers, _default, _encoder, _indent, _floatstr,
             if markers is not None:
                 del markers[markerid]
     return _iterencode
+
+class JSONRepr:
+    def __init__(self, json):
+        self.json = json
+    def __str__(self):
+        return self.json
+
+if 1:
+    # Should be implemented as __json__ methods
+    import decimal
+    def decimal_as_json(o):
+        return JSONRepr(str(o))
+    dispatch_table[decimal.Decimal] = decimal_as_json
diff --git a/Lib/test/test_json/test_default.py b/Lib/test/test_json/test_default.py
index 9b8325e..d6ac542 100644
--- a/Lib/test/test_json/test_default.py
+++ b/Lib/test/test_json/test_default.py
@@ -1,3 +1,9 @@
+import json
+import array
+import collections
+import decimal
+import types
+from collections import OrderedDict
 from test.test_json import PyTest, CTest
 
 
@@ -7,6 +13,83 @@ class TestDefault:
             self.dumps(type, default=repr),
             self.dumps(repr(type)))
 
+    def test_ordereddict(self):
+        self.assertEqual(
+            self.dumps(collections.OrderedDict(a=1, b=2)),
+            '{"a": 1, "b": 2}')
+
+    def test_deque(self):
+        self.assertEqual(
+            self.dumps(collections.deque([1, 2, 3])),
+            '[1, 2, 3]')
+        self.assertEqual(
+            self.dumps(collections.deque([1, 2, 3], maxlen=2)),
+            '[2, 3]')
+
+    def test_chainmap(self):
+        self.assertEqual(
+            self.dumps(collections.ChainMap({'a': 1}, {'a': 2})),
+            '{"a": 1}')
+        self.assertEqual(
+            self.dumps(collections.ChainMap({}, {'a': 2})),
+            '{"a": 2}')
+
+    def test_userdict(self):
+        self.assertEqual(
+            self.dumps(collections.UserDict({'a': 1})),
+            '{"a": 1}')
+
+    def test_userlist(self):
+        self.assertEqual(
+            self.dumps(collections.UserList([1, 2, 3])),
+            '[1, 2, 3]')
+
+    def test_userstring(self):
+        self.assertEqual(
+            self.dumps(collections.UserString('abc')),
+            '"abc"')
+
+    def test_mappingproxy(self):
+        self.assertEqual(
+            self.dumps(types.MappingProxyType(collections.OrderedDict(a=1, b=2))),
+            '{"a": 1, "b": 2}')
+
+    def test_array(self):
+        self.assertEqual(
+            self.dumps(array.array('I', [1, 2, 3])),
+            '[1, 2, 3]')
+
+    def test_decimal(self):
+        self.assertEqual(
+            self.dumps(decimal.Decimal('0.12345678901234567890')),
+            '0.12345678901234567890')
+
+    def test_global_dispatch_table(self):
+        from json.encoder import dispatch_table
+        class A: pass
+        a = A()
+        self.assertRaises(TypeError, json.dumps, a)
+        dispatch_table[A] = repr
+        try:
+            self.assertEqual(json.dumps(a), json.dumps(repr(a)))
+        finally:
+            del dispatch_table[A]
+        self.assertRaises(TypeError, json.dumps, a)
+
+    def test_encoder_dispatch_table(self):
+        class A: pass
+        class Encoder(json.JSONEncoder):
+            dispatch_table = {A: repr}
+        a = A()
+        encoder = Encoder()
+        self.assertEqual(encoder.encode(a), encoder.encode(repr(a)))
+
+    def test_json_method(self):
+        class A:
+            def __json__(self):
+                return repr(self)
+        a = A()
+        self.assertEqual(self.dumps(a), self.dumps(repr(a)))
 
 class TestPyDefault(TestDefault, PyTest): pass
 class TestCDefault(TestDefault, CTest): pass
diff --git a/Modules/_collectionsmodule.c b/Modules/_collectionsmodule.c
index 44e9e11..797f01a 100644
--- a/Modules/_collectionsmodule.c
+++ b/Modules/_collectionsmodule.c
@@ -1544,6 +1544,12 @@ deque_sizeof(dequeobject *deque, void *unused)
 PyDoc_STRVAR(sizeof_doc,
 "D.__sizeof__() -- size of D in memory, in bytes");
 
+static PyObject *
+deque_json(PyObject *deque, PyObject *unused)
+{
+    return PySequence_List(deque);
+}
+
 static int
 deque_bool(dequeobject *deque)
 {
@@ -1636,6 +1642,8 @@ static PyMethodDef deque_methods[] = {
         METH_FASTCALL,            rotate_doc},
     {"__sizeof__",              (PyCFunction)deque_sizeof,
         METH_NOARGS,             sizeof_doc},
+    {"__json__",                deque_json,
+        METH_NOARGS,             NULL},
     {NULL,              NULL}   /* sentinel */
 };
 
diff --git a/Modules/arraymodule.c b/Modules/arraymodule.c
index 464820d..99156b4 100644
--- a/Modules/arraymodule.c
+++ b/Modules/arraymodule.c
@@ -1704,6 +1704,18 @@ array_array___sizeof___impl(arrayobject *self)
 }
 
 
+/*[clinic input]
+array.array.__json__
+[clinic start generated code]*/
+
+static PyObject *
+array_array___json___impl(arrayobject *self)
+/*[clinic end generated code: output=4fd19502af01150b input=467eb79b26564e18]*/
+{
+    return PySequence_List((PyObject *)self);
+}
+
+
 /*********************** Pickling support ************************/
 
 static const struct mformatdescr {
@@ -2227,6 +2239,7 @@ static PyMethodDef array_methods[] = {
     ARRAY_ARRAY_TOBYTES_METHODDEF
     ARRAY_ARRAY_TOUNICODE_METHODDEF
     ARRAY_ARRAY___SIZEOF___METHODDEF
+    ARRAY_ARRAY___JSON___METHODDEF
     {NULL, NULL}  /* sentinel */
 };
 
diff --git a/Modules/clinic/arraymodule.c.h b/Modules/clinic/arraymodule.c.h
index 2a67674..9e05ef1 100644
--- a/Modules/clinic/arraymodule.c.h
+++ b/Modules/clinic/arraymodule.c.h
@@ -447,6 +447,23 @@ array_array___sizeof__(arrayobject *self, PyObject *Py_UNUSED(ignored))
     return array_array___sizeof___impl(self);
 }
 
+PyDoc_STRVAR(array_array___json____doc__,
+"__json__($self, /)\n"
+"--\n"
+"\n");
+
+#define ARRAY_ARRAY___JSON___METHODDEF    \
+    {"__json__", (PyCFunction)array_array___json__, METH_NOARGS, array_array___json____doc__},
+
+static PyObject *
+array_array___json___impl(arrayobject *self);
+
+static PyObject *
+array_array___json__(arrayobject *self, PyObject *Py_UNUSED(ignored))
+{
+    return array_array___json___impl(self);
+}
+
 PyDoc_STRVAR(array__array_reconstructor__doc__,
 "_array_reconstructor($module, arraytype, typecode, mformat_code, items,\n"
 "                     /)\n"
@@ -521,4 +538,4 @@ PyDoc_STRVAR(array_arrayiterator___setstate____doc__,
 
 #define ARRAY_ARRAYITERATOR___SETSTATE___METHODDEF    \
     {"__setstate__", (PyCFunction)array_arrayiterator___setstate__, METH_O, array_arrayiterator___setstate____doc__},
-/*[clinic end generated code: output=d186a7553c1f1a41 input=a9049054013a1b77]*/
+/*[clinic end generated code: output=fe17aed6b96eb7c2 input=a9049054013a1b77]*/
diff --git a/Objects/descrobject.c b/Objects/descrobject.c
index 20c0d36..e42aca1 100644
--- a/Objects/descrobject.c
+++ b/Objects/descrobject.c
@@ -885,6 +885,8 @@ static PyMethodDef mappingproxy_methods[] = {
      PyDoc_STR("D.items() -> list of D's (key, value) pairs, as 2-tuples")},
     {"copy",      (PyCFunction)mappingproxy_copy,       METH_NOARGS,
      PyDoc_STR("D.copy() -> a shallow copy of D")},
+    {"__json__",      (PyCFunction)mappingproxy_copy,       METH_NOARGS,
+     NULL},
     {0}
 };