diff --git a/common/lib/capa/capa/capa_problem.py b/common/lib/capa/capa/capa_problem.py
index 08a223f609..c1eb078a20 100644
--- a/common/lib/capa/capa/capa_problem.py
+++ b/common/lib/capa/capa/capa_problem.py
@@ -25,18 +25,14 @@ from copy import deepcopy
 from capa.correctmap import CorrectMap
 import capa.inputtypes as inputtypes
 import capa.customrender as customrender
+import capa.responsetypes as responsetypes
 from capa.util import contextualize_text, convert_files_to_filenames
 import capa.xqueue_interface as xqueue_interface
 
-# to be replaced with auto-registering
-import capa.responsetypes as responsetypes
 from capa.safe_exec import safe_exec
 
 from pytz import UTC
 
-# dict of tagname, Response Class -- this should come from auto-registering
-response_tag_dict = dict([(x.response_tag, x) for x in responsetypes.__all__])
-
 # extra things displayed after "show answers" is pressed
 solution_tags = ['solution']
 
@@ -652,7 +648,7 @@ class LoncapaProblem(object):
         '''
         response_id = 1
         self.responders = {}
-        for response in tree.xpath('//' + "|//".join(response_tag_dict)):
+        for response in tree.xpath('//' + "|//".join(responsetypes.registry.registered_tags())):
             response_id_str = self.problem_id + "_" + str(response_id)
             # create and save ID for this response
             response.set('id', response_id_str)
@@ -673,8 +669,8 @@ class LoncapaProblem(object):
                 answer_id = answer_id + 1
 
             # instantiate capa Response
-            responder = response_tag_dict[response.tag](response, inputfields,
-                                                        self.context, self.system)
+            responsetype_cls = responsetypes.registry.get_class_for_tag(response.tag)
+            responder = responsetype_cls(response, inputfields, self.context, self.system)
             # save in list in self
             self.responders[response] = responder
 
diff --git a/common/lib/capa/capa/inputtypes.py b/common/lib/capa/capa/inputtypes.py
index 12bee69b01..e81390724d 100644
--- a/common/lib/capa/capa/inputtypes.py
+++ b/common/lib/capa/capa/inputtypes.py
@@ -289,6 +289,7 @@ class InputTypeBase(object):
 #-----------------------------------------------------------------------------
 
 
+@registry.register
 class OptionInput(InputTypeBase):
     """
     Input type for selecting and Select option input type.
@@ -333,14 +334,13 @@ class OptionInput(InputTypeBase):
         return [Attribute('options', transform=cls.parse_options),
                 Attribute('inline', False)]
 
-registry.register(OptionInput)
-
 #-----------------------------------------------------------------------------
 
 
 # TODO: consolidate choicegroup, radiogroup, checkboxgroup after discussion of
 # desired semantics.
 
+@registry.register
 class ChoiceGroup(InputTypeBase):
     """
     Radio button or checkbox inputs: multiple choice or true/false
@@ -415,12 +415,10 @@ class ChoiceGroup(InputTypeBase):
         return choices
 
 
-registry.register(ChoiceGroup)
-
-
 #-----------------------------------------------------------------------------
 
 
+@registry.register
 class JavascriptInput(InputTypeBase):
     """
     Hidden field for javascript to communicate via; also loads the required
@@ -451,13 +449,11 @@ class JavascriptInput(InputTypeBase):
         if self.value == "":
             self.value = 'null'
 
-registry.register(JavascriptInput)
-
-
 
 #-----------------------------------------------------------------------------
 
 
+@registry.register
 class JSInput(InputTypeBase):
     """
     Inputtype for general javascript inputs. Intended to be used with
@@ -480,7 +476,7 @@ class JSInput(InputTypeBase):
                  height="500"
                  width="400"/>
 
-    See the documentation in docs/data/source/course_data_formats/jsinput.rst 
+    See the documentation in docs/data/source/course_data_formats/jsinput.rst
     for more information.
     """
 
@@ -517,11 +513,10 @@ class JSInput(InputTypeBase):
 
         return context
 
-
-registry.register(JSInput)
 #-----------------------------------------------------------------------------
 
 
+@registry.register
 class TextLine(InputTypeBase):
     """
     A text line input.  Can do math preview if "math"="1" is specified.
@@ -587,11 +582,10 @@ class TextLine(InputTypeBase):
         return {'do_math': self.do_math,
                 'preprocessor': self.preprocessor, }
 
-registry.register(TextLine)
-
 #-----------------------------------------------------------------------------
 
 
+@registry.register
 class FileSubmission(InputTypeBase):
     """
     Upload some files (e.g. for programming assignments)
@@ -636,11 +630,10 @@ class FileSubmission(InputTypeBase):
     def _extra_context(self):
         return {'queue_len': self.queue_len, }
 
-registry.register(FileSubmission)
-
 
 #-----------------------------------------------------------------------------
 
+@registry.register
 class CodeInput(InputTypeBase):
     """
     A text area input for code--uses codemirror, does syntax highlighting, special tab handling,
@@ -700,12 +693,11 @@ class CodeInput(InputTypeBase):
         """Defined queue_len, add it """
         return {'queue_len': self.queue_len, }
 
-registry.register(CodeInput)
-
 
 #-----------------------------------------------------------------------------
 
 
+@registry.register
 class MatlabInput(CodeInput):
     '''
     InputType for handling Matlab code input
@@ -866,11 +858,9 @@ class MatlabInput(CodeInput):
         return {'success': error == 0, 'message': msg}
 
 
-registry.register(MatlabInput)
-
-
 #-----------------------------------------------------------------------------
 
+@registry.register
 class Schematic(InputTypeBase):
     """
     InputType for the schematic editor
@@ -893,11 +883,10 @@ class Schematic(InputTypeBase):
             Attribute('submit_analyses', None), ]
 
 
-registry.register(Schematic)
-
 #-----------------------------------------------------------------------------
 
 
+@registry.register
 class ImageInput(InputTypeBase):
     """
     Clickable image as an input field.  Element should specify the image source, height,
@@ -939,11 +928,10 @@ class ImageInput(InputTypeBase):
         return {'gx': self.gx,
                 'gy': self.gy}
 
-registry.register(ImageInput)
-
 #-----------------------------------------------------------------------------
 
 
+@registry.register
 class Crystallography(InputTypeBase):
     """
     An input for crystallography -- user selects 3 points on the axes, and we get a plane.
@@ -963,11 +951,10 @@ class Crystallography(InputTypeBase):
                 Attribute('width'),
                 ]
 
-registry.register(Crystallography)
-
 # -------------------------------------------------------------------------
 
 
+@registry.register
 class VseprInput(InputTypeBase):
     """
     Input for molecular geometry--show possible structures, let student
@@ -988,11 +975,10 @@ class VseprInput(InputTypeBase):
                 Attribute('geometries'),
                 ]
 
-registry.register(VseprInput)
-
 #-------------------------------------------------------------------------
 
 
+@registry.register
 class ChemicalEquationInput(InputTypeBase):
     """
     An input type for entering chemical equations.  Supports live preview.
@@ -1064,11 +1050,10 @@ class ChemicalEquationInput(InputTypeBase):
 
         return result
 
-registry.register(ChemicalEquationInput)
-
 #-------------------------------------------------------------------------
 
 
+@registry.register
 class FormulaEquationInput(InputTypeBase):
     """
     An input type for entering formula equations.  Supports live preview.
@@ -1160,11 +1145,10 @@ class FormulaEquationInput(InputTypeBase):
 
         return result
 
-registry.register(FormulaEquationInput)
-
 #-----------------------------------------------------------------------------
 
 
+@registry.register
 class DragAndDropInput(InputTypeBase):
     """
     Input for drag and drop problems. Allows student to drag and drop images and
@@ -1259,11 +1243,10 @@ class DragAndDropInput(InputTypeBase):
         self.loaded_attributes['drag_and_drop_json'] = json.dumps(to_js)
         self.to_render.add('drag_and_drop_json')
 
-registry.register(DragAndDropInput)
-
 #-------------------------------------------------------------------------
 
 
+@registry.register
 class EditAMoleculeInput(InputTypeBase):
     """
     An input type for edit-a-molecule.  Integrates with the molecule editor java applet.
@@ -1296,11 +1279,10 @@ class EditAMoleculeInput(InputTypeBase):
 
         return context
 
-registry.register(EditAMoleculeInput)
-
 #-----------------------------------------------------------------------------
 
 
+@registry.register
 class DesignProtein2dInput(InputTypeBase):
     """
     An input type for design of a protein in 2D. Integrates with the Protex java applet.
@@ -1333,11 +1315,10 @@ class DesignProtein2dInput(InputTypeBase):
 
         return context
 
-registry.register(DesignProtein2dInput)
-
 #-----------------------------------------------------------------------------
 
 
+@registry.register
 class EditAGeneInput(InputTypeBase):
     """
         An input type for editing a gene.
@@ -1370,11 +1351,10 @@ class EditAGeneInput(InputTypeBase):
 
         return context
 
-registry.register(EditAGeneInput)
-
 #---------------------------------------------------------------------
 
 
+@registry.register
 class AnnotationInput(InputTypeBase):
     """
     Input type for annotations: students can enter some notes or other text
@@ -1481,9 +1461,8 @@ class AnnotationInput(InputTypeBase):
 
         return extra_context
 
-registry.register(AnnotationInput)
-
 
+@registry.register
 class ChoiceTextGroup(InputTypeBase):
     """
     Groups of radiobutton/checkboxes with text inputs.
@@ -1686,5 +1665,3 @@ class ChoiceTextGroup(InputTypeBase):
             # Add the tuple for the current choice to the list of choices
             choices.append((choice.get("name"), components))
         return choices
-
-registry.register(ChoiceTextGroup)
diff --git a/common/lib/capa/capa/registry.py b/common/lib/capa/capa/registry.py
index 94a2853dec..bcc002c046 100644
--- a/common/lib/capa/capa/registry.py
+++ b/common/lib/capa/capa/registry.py
@@ -1,3 +1,5 @@
+"""A registry for finding classes based on tags in the class."""
+
 class TagRegistry(object):
     """
     A registry mapping tags to handlers.
@@ -35,6 +37,9 @@ class TagRegistry(object):
         for t in cls.tags:
             self._mapping[t] = cls
 
+        # Returning the cls means we can use this as a decorator.
+        return cls
+
     def registered_tags(self):
         """
         Get a list of all the tags that have been registered.
diff --git a/common/lib/capa/capa/responsetypes.py b/common/lib/capa/capa/responsetypes.py
index ac19fd1907..3bdd154525 100644
--- a/common/lib/capa/capa/responsetypes.py
+++ b/common/lib/capa/capa/responsetypes.py
@@ -33,6 +33,7 @@ from shapely.geometry import Point, MultiPoint
 # specific library imports
 from calc import evaluator, UndefinedVariable
 from . import correctmap
+from .registry import TagRegistry
 from datetime import datetime
 from pytz import UTC
 from .util import (compare_with_tolerance, contextualize_text,  convert_files_to_filenames,
@@ -45,6 +46,7 @@ import capa.safe_exec as safe_exec
 
 log = logging.getLogger(__name__)
 
+registry = TagRegistry()
 
 CorrectMap = correctmap.CorrectMap  # pylint: disable=C0103
 CORRECTMAP_PY = None
@@ -92,7 +94,7 @@ class LoncapaResponse(object):
 
     Each subclass must also define the following attributes:
 
-      - response_tag         : xhtml tag identifying this response (used in auto-registering)
+      - tags                : xhtml tags identifying this response (used in auto-registering)
 
     In addition, these methods are optional:
 
@@ -120,7 +122,7 @@ class LoncapaResponse(object):
     """
     __metaclass__ = abc.ABCMeta  # abc = Abstract Base Class
 
-    response_tag = None
+    tags = None
     hint_tag = None
 
     max_inputfields = None
@@ -405,13 +407,14 @@ class LoncapaResponse(object):
 
 #-----------------------------------------------------------------------------
 
+@registry.register
 class JavascriptResponse(LoncapaResponse):
     """
     This response type is used when the student's answer is graded via
     Javascript using Node.js.
     """
 
-    response_tag = 'javascriptresponse'
+    tags = ['javascriptresponse']
     max_inputfields = 1
     allowed_inputfields = ['javascriptinput']
 
@@ -605,6 +608,7 @@ class JavascriptResponse(LoncapaResponse):
 
 
 #-----------------------------------------------------------------------------
+@registry.register
 class ChoiceResponse(LoncapaResponse):
     """
     This response type is used when the student chooses from a discrete set of
@@ -653,7 +657,7 @@ class ChoiceResponse(LoncapaResponse):
 
     """
 
-    response_tag = 'choiceresponse'
+    tags = ['choiceresponse']
     max_inputfields = 1
     allowed_inputfields = ['checkboxgroup', 'radiogroup']
     correct_choices = None
@@ -702,10 +706,11 @@ class ChoiceResponse(LoncapaResponse):
 #-----------------------------------------------------------------------------
 
 
+@registry.register
 class MultipleChoiceResponse(LoncapaResponse):
     # TODO: handle direction and randomize
 
-    response_tag = 'multiplechoiceresponse'
+    tags = ['multiplechoiceresponse']
     max_inputfields = 1
     allowed_inputfields = ['choicegroup']
     correct_choices = None
@@ -759,9 +764,10 @@ class MultipleChoiceResponse(LoncapaResponse):
         return {self.answer_id: self.correct_choices}
 
 
+@registry.register
 class TrueFalseResponse(MultipleChoiceResponse):
 
-    response_tag = 'truefalseresponse'
+    tags = ['truefalseresponse']
 
     def mc_setup_response(self):
         i = 0
@@ -786,12 +792,13 @@ class TrueFalseResponse(MultipleChoiceResponse):
 #-----------------------------------------------------------------------------
 
 
+@registry.register
 class OptionResponse(LoncapaResponse):
     '''
     TODO: handle direction and randomize
     '''
 
-    response_tag = 'optionresponse'
+    tags = ['optionresponse']
     hint_tag = 'optionhint'
     allowed_inputfields = ['optioninput']
     answer_fields = None
@@ -819,13 +826,14 @@ class OptionResponse(LoncapaResponse):
 #-----------------------------------------------------------------------------
 
 
+@registry.register
 class NumericalResponse(LoncapaResponse):
     '''
     This response type expects a number or formulaic expression that evaluates
     to a number (e.g. `4+5/2^2`), and accepts with a tolerance.
     '''
 
-    response_tag = 'numericalresponse'
+    tags = ['numericalresponse']
     hint_tag = 'numericalhint'
     allowed_inputfields = ['textline', 'formulaequationinput']
     required_attributes = ['answer']
@@ -946,6 +954,7 @@ class NumericalResponse(LoncapaResponse):
 #-----------------------------------------------------------------------------
 
 
+@registry.register
 class StringResponse(LoncapaResponse):
     '''
     This response type allows one or more answers.
@@ -978,7 +987,7 @@ class StringResponse(LoncapaResponse):
             </hintgroup>
         </stringresponse>
     '''
-    response_tag = 'stringresponse'
+    tags = ['stringresponse']
     hint_tag = 'stringhint'
     allowed_inputfields = ['textline']
     required_attributes = ['answer']
@@ -1080,13 +1089,14 @@ class StringResponse(LoncapaResponse):
 #-----------------------------------------------------------------------------
 
 
+@registry.register
 class CustomResponse(LoncapaResponse):
     '''
     Custom response.  The python code to be run should be in <answer>...</answer>
     or in a <script>...</script>
     '''
 
-    response_tag = 'customresponse'
+    tags = ['customresponse']
 
     allowed_inputfields = ['textline', 'textbox', 'crystallography',
                            'chemicalequationinput', 'vsepr_input',
@@ -1408,12 +1418,13 @@ class CustomResponse(LoncapaResponse):
 #-----------------------------------------------------------------------------
 
 
+@registry.register
 class SymbolicResponse(CustomResponse):
     """
     Symbolic math response checking, using symmath library.
     """
 
-    response_tag = 'symbolicresponse'
+    tags = ['symbolicresponse']
     max_inputfields = 1
 
     def setup_response(self):
@@ -1456,6 +1467,7 @@ class SymbolicResponse(CustomResponse):
 ScoreMessage = namedtuple('ScoreMessage', ['valid', 'correct', 'points', 'msg'])  # pylint: disable=invalid-name
 
 
+@registry.register
 class CodeResponse(LoncapaResponse):
     """
     Grade student code using an external queueing server, called 'xqueue'
@@ -1472,7 +1484,7 @@ class CodeResponse(LoncapaResponse):
         (i.e. and not for getting reference answers)
     """
 
-    response_tag = 'coderesponse'
+    tags = ['coderesponse']
     allowed_inputfields = ['textbox', 'filesubmission', 'matlabinput']
     max_inputfields = 1
     payload = None
@@ -1705,6 +1717,7 @@ class CodeResponse(LoncapaResponse):
 #-----------------------------------------------------------------------------
 
 
+@registry.register
 class ExternalResponse(LoncapaResponse):
     """
     Grade the students input using an external server.
@@ -1713,7 +1726,7 @@ class ExternalResponse(LoncapaResponse):
 
     """
 
-    response_tag = 'externalresponse'
+    tags = ['externalresponse']
     allowed_inputfields = ['textline', 'textbox']
     awdmap = {
         'EXACT_ANS': 'correct',         # TODO: handle other loncapa responses
@@ -1864,12 +1877,13 @@ class ExternalResponse(LoncapaResponse):
 
 #-----------------------------------------------------------------------------
 
+@registry.register
 class FormulaResponse(LoncapaResponse):
     """
     Checking of symbolic math response using numerical sampling.
     """
 
-    response_tag = 'formularesponse'
+    tags = ['formularesponse']
     hint_tag = 'formulahint'
     allowed_inputfields = ['textline', 'formulaequationinput']
     required_attributes = ['answer', 'samples']
@@ -2068,11 +2082,12 @@ class FormulaResponse(LoncapaResponse):
 #-----------------------------------------------------------------------------
 
 
+@registry.register
 class SchematicResponse(LoncapaResponse):
     """
     Circuit schematic response type.
     """
-    response_tag = 'schematicresponse'
+    tags = ['schematicresponse']
     allowed_inputfields = ['schematic']
 
     def __init__(self, *args, **kwargs):
@@ -2118,6 +2133,7 @@ class SchematicResponse(LoncapaResponse):
 #-----------------------------------------------------------------------------
 
 
+@registry.register
 class ImageResponse(LoncapaResponse):
     """
     Handle student response for image input: the input is a click on an image,
@@ -2145,7 +2161,7 @@ class ImageResponse(LoncapaResponse):
         True, if click is inside any region or rectangle. Otherwise False.
     """
 
-    response_tag = 'imageresponse'
+    tags = ['imageresponse']
     allowed_inputfields = ['imageinput']
 
     def __init__(self, *args, **kwargs):
@@ -2248,6 +2264,7 @@ class ImageResponse(LoncapaResponse):
 #-----------------------------------------------------------------------------
 
 
+@registry.register
 class AnnotationResponse(LoncapaResponse):
     """
     Checking of annotation responses.
@@ -2255,7 +2272,7 @@ class AnnotationResponse(LoncapaResponse):
     The response contains both a comment (student commentary) and an option (student tag).
     Only the tag is currently graded. Answers may be incorrect, partially correct, or correct.
     """
-    response_tag = 'annotationresponse'
+    tags = ['annotationresponse']
     allowed_inputfields = ['annotationinput']
     max_inputfields = 1
     default_scoring = {'incorrect': 0, 'partially-correct': 1, 'correct': 2}
@@ -2371,6 +2388,7 @@ class AnnotationResponse(LoncapaResponse):
         return None
 
 
+@registry.register
 class ChoiceTextResponse(LoncapaResponse):
     """
     Allows for multiple choice responses with text inputs
@@ -2378,7 +2396,7 @@ class ChoiceTextResponse(LoncapaResponse):
     ChoiceResponse.
     """
 
-    response_tag = 'choicetextresponse'
+    tags = ['choicetextresponse']
     max_inputfields = 1
     allowed_inputfields = ['choicetextgroup',
                            'checkboxtextgroup',