diff --git a/README.md b/README.md
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index 0000000..2c6f2cb
--- /dev/null
+++ b/README.md
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+```
+spam_checker:
+  - module: limiter.Limiter
+    config:
+      limit: 750
+      protected_rooms:
+        - "!foobarbaz:matrix.org"
+        - "!barbazquz:matrix.org"
+```
diff --git a/limiter/__init__.py b/limiter/__init__.py
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+++ b/limiter/__init__.py
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+from .limiter import Limiter
diff --git a/limiter/limiter.py b/limiter/limiter.py
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+++ b/limiter/limiter.py
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+# -*- coding: utf-8 -*-
+# Copyright 2019 The Matrix.org Foundation C.I.C.
+#
+# 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.
+
+class Limiter(object):
+    def __init__(self, config, api):
+        self.api = api
+        self.limit = config.get("limit", 1000)
+        self.protected_rooms = config.get("protected_rooms", [])
+
+    # --- spam checker interface below here ---
+
+    def check_event_for_spam(self, event):
+        body = event.get("content", {}).get("body", "")
+        room_id = event.get("room_id", "")
+        if room_id in self.protected_rooms and len(body) > self.limit:
+            return True # It's over the limit
+        return False  # not spam (as far as we're concerned)
+
+    def user_may_invite(self, inviter_user_id, invitee_user_id, room_id):
+        return True  # allowed (as far as we're concerned)
+
+    def check_username_for_spam(self, user_profile):
+        return True
+
+    def user_may_create_room(self, user_id):
+        return True  # allowed
+
+    def user_may_create_room_alias(self, user_id, room_alias):
+        return True  # allowed
+
+    def user_may_publish_room(self, user_id, room_id):
+        return True  # allowed
+
+    @staticmethod
+    def parse_config(config):
+        return config  # no parsing needed
diff --git a/setup.py b/setup.py
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+++ b/setup.py
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+from setuptools import setup, find_packages
+
+setup(
+    name="limiter",
+    version="0.0.1",
+    packages=find_packages(),
+    description="Limiter",
+    include_package_data=True,
+    zip_safe=True,
+    install_requires=[],
+)