diff --git a/openhtf/output/callbacks/json_factory.py b/openhtf/output/callbacks/json_factory.py
index b6b6fdf5d..796135ecf 100644
--- a/openhtf/output/callbacks/json_factory.py
+++ b/openhtf/output/callbacks/json_factory.py
@@ -6,19 +6,10 @@
 from openhtf.core import test_record
 from openhtf.output import callbacks
 from openhtf.util import data
+from openhtf.util import json_encoder
 import six
 
 
-class TestRecordEncoder(json.JSONEncoder):
-
-  def default(self, obj):
-    if isinstance(obj, test_record.Attachment):
-      dct = obj._asdict()
-      dct['data'] = base64.standard_b64encode(obj.data).decode('utf-8')
-      return dct
-    return super(TestRecordEncoder, self).default(obj)
-
-
 class OutputToJSON(callbacks.OutputToFile):
   """Return an output callback that writes JSON Test Records.
 
@@ -47,7 +38,7 @@ def __init__(self, filename_pattern=None, inline_attachments=True, **kwargs):
     # Conform strictly to the JSON spec by default.
     kwargs.setdefault('allow_nan', False)
     self.allow_nan = kwargs['allow_nan']
-    self.json_encoder = TestRecordEncoder(**kwargs)
+    self.json_encoder = json_encoder.TestRecordEncoder(**kwargs)
 
   def serialize_test_record(self, test_record):
     return self.json_encoder.iterencode(self.convert_to_dict(test_record))
diff --git a/openhtf/output/proto/mfg_event_converter.py b/openhtf/output/proto/mfg_event_converter.py
index 1c1acb989..5e6525a59 100644
--- a/openhtf/output/proto/mfg_event_converter.py
+++ b/openhtf/output/proto/mfg_event_converter.py
@@ -23,6 +23,7 @@
 from openhtf.util import data as htf_data
 from openhtf.util import units
 from openhtf.util import validators
+from openhtf.util import json_encoder
 
 
 from past.builtins import unicode
@@ -172,9 +173,9 @@ def _convert_object_to_json(obj):
   # Since there will be parts of this that may have unicode, either as
   # measurement or in the logs, we have to be careful and convert everything
   # to unicode, merge, then encode to UTF-8 to put it into the proto.
-  json_encoder = json.JSONEncoder(sort_keys=True, indent=2, ensure_ascii=False)
+  encoder = json_encoder.TestRecordEncoder(sort_keys=True, indent=2, ensure_ascii=False)
   pieces = []
-  for piece in json_encoder.iterencode(obj):
+  for piece in encoder.iterencode(obj):
     if isinstance(piece, bytes):
       pieces.append(unicode(piece, errors='replace'))
     else:
diff --git a/openhtf/output/servers/station_server.py b/openhtf/output/servers/station_server.py
index fe20bb2bb..d6bc9d6da 100644
--- a/openhtf/output/servers/station_server.py
+++ b/openhtf/output/servers/station_server.py
@@ -29,6 +29,7 @@
 from openhtf.util import logs
 from openhtf.util import multicast
 from openhtf.util import timeouts
+from openhtf.util import json_encoder
 
 STATION_SERVER_TYPE = 'station'
 
@@ -556,6 +557,11 @@ def __init__(self, history_path=None):
     if not tornado_logger.handlers:
       tornado_logger.addHandler(logging.NullHandler())
 
+    # Override tornado's json encoding to handle our Attachments.
+    def _json_encode(value):
+      return json_encoder.TestRecordEncoder().encode(value)
+    sockjs.tornado.proto.json_encode = _json_encode
+
     # Bind port early so that the correct port number can be used in the routes.
     sockets, port = web_gui_server.bind_port(int(conf.station_server_port))
 
diff --git a/openhtf/util/json_encoder.py b/openhtf/util/json_encoder.py
new file mode 100644
index 000000000..bd3ede332
--- /dev/null
+++ b/openhtf/util/json_encoder.py
@@ -0,0 +1,29 @@
+# Copyright 2016 Google Inc. All Rights Reserved.
+
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+
+#     http://www.apache.org/licenses/LICENSE-2.0
+
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import base64
+import json
+
+from openhtf.core import test_record
+
+
+class TestRecordEncoder(json.JSONEncoder):
+  """JSON encoder that supports Attachments."""
+
+  def default(self, obj):
+    if isinstance(obj, test_record.Attachment):
+      dct = obj._asdict()
+      dct['data'] = base64.standard_b64encode(obj.data).decode('utf-8')
+      return dct
+    return super(TestRecordEncoder, self).default(obj)