diff --git a/example-config.yaml b/example-config.yaml
index 7d8e61b..a951ae9 100644
--- a/example-config.yaml
+++ b/example-config.yaml
@@ -1,3 +1,8 @@
+# The full URI to the database. SQLite and Postgres are fully supported.
+# Other DBMSes supported by SQLAlchemy may or may not work.
+# Format examples:
+#   SQLite:   sqlite:///filename.db
+#   Postgres: postgres://username:password@hostname/dbname
 database: sqlite:///maubot.db
 
 # If multiple directories have a plugin with the same name, the first directory is used.
@@ -5,8 +10,15 @@ plugin_directories:
 - ./plugins
 
 server:
+    # The IP:port to listen to.
     listen: 0.0.0.0:29316
+    # The base management API path.
     base_path: /_matrix/maubot
+    # The base appservice API path. Use / for legacy appservice API and /_matrix/app/v1 for v1.
+    appservice_base_path: /_matrix/app/v1
+    # The shared secret to authorize users of the API.
+    # Set to "generate" to generate and save a new token at startup.
+    shared_secret: generate
 
 admins:
 - "@admin:example.com"
diff --git a/maubot/__init__.py b/maubot/__init__.py
index 038c1c1..9c3cbb8 100644
--- a/maubot/__init__.py
+++ b/maubot/__init__.py
@@ -1 +1,3 @@
-__version__ = "0.1.0+dev"
+from .plugin_base import Plugin
+from .command_spec import CommandSpec, Command, PassiveCommand, Argument
+from .event import FakeEvent as Event
diff --git a/maubot/__main__.py b/maubot/__main__.py
index 67112bc..2b97589 100644
--- a/maubot/__main__.py
+++ b/maubot/__main__.py
@@ -20,7 +20,7 @@ import argparse
 import copy
 
 from .config import Config
-from . import __version__
+from .__meta__ import __version__
 
 parser = argparse.ArgumentParser(description="A plugin-based Matrix bot system.",
                                  prog="python -m maubot")
diff --git a/maubot/__meta__.py b/maubot/__meta__.py
new file mode 100644
index 0000000..038c1c1
--- /dev/null
+++ b/maubot/__meta__.py
@@ -0,0 +1 @@
+__version__ = "0.1.0+dev"
diff --git a/maubot/client.py b/maubot/client.py
index 3d73b3f..539ca54 100644
--- a/maubot/client.py
+++ b/maubot/client.py
@@ -42,11 +42,11 @@ class Client:
             self.client.add_event_handler(self.handle_invite, EventType.ROOM_MEMBER)
 
     @classmethod
-    def get(cls, id: UserID) -> Optional['Client']:
+    def get(cls, user_id: UserID) -> Optional['Client']:
         try:
-            return cls.cache[id]
+            return cls.cache[user_id]
         except KeyError:
-            db_instance = DBClient.query.get(id)
+            db_instance = DBClient.query.get(user_id)
             if not db_instance:
                 return None
             return Client(db_instance)
@@ -126,6 +126,6 @@ class Client:
 
     # endregion
 
-    async def handle_invite(self, evt: StateEvent):
+    async def handle_invite(self, evt: StateEvent) -> None:
         if evt.state_key == self.id and evt.content.membership == Membership.INVITE:
             await self.client.join_room_by_id(evt.room_id)
diff --git a/maubot/command_spec.py b/maubot/command_spec.py
new file mode 100644
index 0000000..8ac6e23
--- /dev/null
+++ b/maubot/command_spec.py
@@ -0,0 +1,52 @@
+# maubot - A plugin-based Matrix bot system.
+# Copyright (C) 2018 Tulir Asokan
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+from typing import List, Dict
+from attr import dataclass
+
+from mautrix.types import Event
+from mautrix.client.api.types.util import SerializableAttrs
+
+
+@dataclass
+class Argument(SerializableAttrs['Argument']):
+    matches: str
+    required: bool = False
+    description: str = None
+
+
+@dataclass
+class Command(SerializableAttrs['Command']):
+    syntax: str
+    arguments: Dict[str, Argument]
+    description: str = None
+
+
+@dataclass
+class PassiveCommand(SerializableAttrs['PassiveCommand']):
+    name: str
+    matches: str
+    match_against: str
+    match_event: Event = None
+
+
+@dataclass
+class CommandSpec(SerializableAttrs['CommandSpec']):
+    commands: List[Command] = []
+    passive_commands: List[PassiveCommand] = []
+
+    def __add__(self, other: 'CommandSpec') -> 'CommandSpec':
+        return CommandSpec(commands=self.commands + other.commands,
+                           passive_commands=self.passive_commands + other.passive_commands)
diff --git a/maubot/db.py b/maubot/db.py
index 812cc3e..841dbe8 100644
--- a/maubot/db.py
+++ b/maubot/db.py
@@ -47,9 +47,9 @@ class DBPlugin(Base):
     id: str = Column(String(255), primary_key=True)
     type: str = Column(String(255), nullable=False)
     enabled: bool = Column(Boolean, nullable=False, default=False)
-    primary_user: str = Column(String(255),
-                               ForeignKey("client.id", onupdate="CASCADE", ondelete="RESTRICT"),
-                               nullable=False)
+    primary_user: UserID = Column(String(255),
+                                  ForeignKey("client.id", onupdate="CASCADE", ondelete="RESTRICT"),
+                                  nullable=False)
 
 
 class DBClient(Base):
diff --git a/maubot/event.py b/maubot/event.py
new file mode 100644
index 0000000..b779529
--- /dev/null
+++ b/maubot/event.py
@@ -0,0 +1,64 @@
+# maubot - A plugin-based Matrix bot system.
+# Copyright (C) 2018 Tulir Asokan
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+from typing import Awaitable, Union
+
+from mautrix.types import Event as MatrixEvent, EventType, MessageEventContent, MessageType, EventID
+from mautrix.client.api.types.event.base import BaseRoomEvent
+from mautrix.client import ClientAPI
+
+
+class FakeEvent(BaseRoomEvent):
+    def __new__(cls, *args, **kwargs):
+        raise RuntimeError("Can't create instance of type hint header class")
+
+    def respond(self, content: Union[str, MessageEventContent],
+                event_type: EventType = EventType.ROOM_MESSAGE) -> Awaitable[EventID]:
+        raise RuntimeError("Can't call methods of type hint header class")
+
+    def reply(self, content: Union[str, MessageEventContent],
+              event_type: EventType = EventType.ROOM_MESSAGE) -> Awaitable[EventID]:
+        raise RuntimeError("Can't call methods of type hint header class")
+
+    def mark_read(self) -> Awaitable[None]:
+        raise RuntimeError("Can't call methods of type hint header class")
+
+
+class Event:
+    def __init__(self, client: ClientAPI, target: MatrixEvent):
+        self.client: ClientAPI = client
+        self.target: MatrixEvent = target
+
+    def __getattr__(self, item):
+        return getattr(self.target, item)
+
+    def __setattr__(self, key, value):
+        return setattr(self.target, key, value)
+
+    def respond(self, content: Union[str, MessageEventContent],
+                event_type: EventType = EventType.ROOM_MESSAGE) -> Awaitable[EventID]:
+        if isinstance(content, str):
+            content = MessageEventContent(msgtype=MessageType.TEXT, body=content)
+        return self.client.send_message_event(self.target.room_id, event_type, content)
+
+    def reply(self, content: Union[str, MessageEventContent],
+              event_type: EventType = EventType.ROOM_MESSAGE) -> Awaitable[EventID]:
+        if isinstance(content, str):
+            content = MessageEventContent(msgtype=MessageType.TEXT, body=content)
+        content.set_reply(self.target)
+        return self.client.send_message_event(self.target.room_id, event_type, content)
+
+    def mark_read(self) -> Awaitable[None]:
+        return self.client.send_receipt(self.target.room_id, self.target.event_id, "m.read")
diff --git a/tmp/fzipimport.py b/maubot/lib/zipimport.py
similarity index 98%
rename from tmp/fzipimport.py
rename to maubot/lib/zipimport.py
index f829309..0ef16cf 100644
--- a/tmp/fzipimport.py
+++ b/maubot/lib/zipimport.py
@@ -1,3 +1,9 @@
+# The pure Python implementation of zipimport in Python 3.8+. Slightly modified to allow clearing
+# the zip directory cache to bypass https://bugs.python.org/issue19081
+#
+# https://github.com/python/cpython/blob/5a5ce064b3baadcb79605c5a42ee3d0aee57cdfc/Lib/zipimport.py
+# See license at https://github.com/python/cpython/blob/master/LICENSE
+
 """zipimport provides support for importing Python modules from Zip archives.
 
 This module exports three objects:
diff --git a/maubot/plugin.py b/maubot/plugin.py
new file mode 100644
index 0000000..b952af0
--- /dev/null
+++ b/maubot/plugin.py
@@ -0,0 +1,190 @@
+# maubot - A plugin-based Matrix bot system.
+# Copyright (C) 2018 Tulir Asokan
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+from typing import Dict, List, TypeVar, Type
+from zipfile import ZipFile, BadZipFile
+import logging
+import sys
+import os
+import io
+import configparser
+
+from mautrix.types import UserID
+
+from .lib.zipimport import zipimporter, ZipImportError
+from .db import DBPlugin
+from .plugin_base import Plugin
+
+log = logging.getLogger("maubot.plugin")
+PluginClass = TypeVar("PluginClass", bound=Plugin)
+
+class MaubotImportError(Exception):
+    pass
+
+
+class ZippedModule:
+    path_cache: Dict[str, 'ZippedModule'] = {}
+    id_cache: Dict[str, 'ZippedModule'] = {}
+
+    path: str
+    id: str
+    version: str
+    modules: List[str]
+    main_class: str
+    main_module: str
+    loaded: bool
+    _importer: zipimporter
+
+    def __init__(self, path: str) -> None:
+        self.path = path
+        self.id = None
+        self.loaded = False
+        self._load_meta()
+        self._run_preload_checks(self._get_importer())
+        self.path_cache[self.path] = self
+        self.id_cache[self.id] = self
+
+    def __repr__(self) -> str:
+        return ("<maubot.plugin.ZippedModule "
+                f"path='{self.path}' "
+                f"id='{self.id}' "
+                f"loaded={self.loaded}>")
+
+    def _load_meta(self) -> None:
+        try:
+            file = ZipFile(self.path)
+            data = file.read("maubot.ini")
+        except FileNotFoundError as e:
+            raise MaubotImportError(f"Maubot plugin not found at {self.path}") from e
+        except BadZipFile as e:
+            raise MaubotImportError(f"File at {self.path} is not a maubot plugin") from e
+        except KeyError as e:
+            raise MaubotImportError(
+                "File at {path} does not contain a maubot plugin definition") from e
+        config = configparser.ConfigParser()
+        try:
+            config.read_string(data.decode("utf-8"), source=f"{self.path}/maubot.ini")
+            meta = config["maubot"]
+            meta_id = meta["ID"]
+            version = meta["Version"]
+            modules = [mod.strip() for mod in meta["Modules"].split(",")]
+            main_class = meta["MainClass"]
+            main_module = modules[-1]
+            if "/" in main_class:
+                main_module, main_class = main_class.split("/")[:2]
+        except (configparser.Error, KeyError, IndexError, ValueError) as e:
+            raise MaubotImportError(
+                f"Maubot plugin definition in file at {self.path} is invalid") from e
+        if self.id and meta_id != self.id:
+            raise MaubotImportError("Maubot plugin ID changed during reload")
+        self.id, self.version, self.modules = meta_id, version, modules
+        self.main_class, self.main_module = main_class, main_module
+
+    def _get_importer(self, reset_cache: bool = False) -> zipimporter:
+        try:
+            importer = zipimporter(self.path)
+            if reset_cache:
+                importer.reset_cache()
+            return importer
+        except ZipImportError as e:
+            raise MaubotImportError(f"File at {self.path} not found or not a maubot plugin") from e
+
+    def _run_preload_checks(self, importer: zipimporter) -> None:
+        try:
+            code = importer.get_code(self.main_module.replace(".", "/"))
+            if self.main_class not in code.co_names:
+                raise MaubotImportError(f"Main class {self.main_class} not in {self.main_module}")
+        except ZipImportError as e:
+            raise MaubotImportError(
+                f"Main module {self.main_module} not found in {self.path}") from e
+        for module in self.modules:
+            try:
+                importer.find_module(module)
+            except ZipImportError as e:
+                raise MaubotImportError(f"Module {module} not found in {self.path}") from e
+
+    def load(self) -> Type[PluginClass]:
+        importer = self._get_importer(reset_cache=self.loaded)
+        self._run_preload_checks(importer)
+        for module in self.modules:
+            importer.load_module(module)
+        self.loaded = True
+        main_mod = sys.modules[self.main_module]
+        plugin = getattr(main_mod, self.main_class)
+        if not issubclass(plugin, Plugin):
+            raise MaubotImportError(
+                f"Main class of plugin at {self.path} does not extend maubot.Plugin")
+        return plugin
+
+    def reload(self) -> Type[PluginClass]:
+        self.unload()
+        return self.load()
+
+    def unload(self) -> None:
+        for name, mod in list(sys.modules.items()):
+            if getattr(mod, "__file__", "").startswith(self.path):
+                del sys.modules[name]
+
+    def destroy(self) -> None:
+        self.unload()
+        try:
+            del self.path_cache[self.path]
+        except KeyError:
+            pass
+        try:
+            del self.id_cache[self.id]
+        except KeyError:
+            pass
+
+
+class PluginInstance:
+    cache: Dict[str, 'PluginInstance'] = {}
+    plugin_directories: List[str] = []
+
+    def __init__(self, db_instance: DBPlugin):
+        self.db_instance = db_instance
+        self.cache[self.id] = self
+
+    @property
+    def id(self) -> str:
+        return self.db_instance.id
+
+    @id.setter
+    def id(self, value: str) -> None:
+        self.db_instance.id = value
+
+    @property
+    def type(self) -> str:
+        return self.db_instance.type
+
+    @type.setter
+    def type(self, value: str) -> None:
+        self.db_instance.type = value
+
+    @property
+    def enabled(self) -> bool:
+        return self.db_instance.enabled
+
+    @enabled.setter
+    def enabled(self, value: bool) -> None:
+        self.db_instance.enabled = value
+
+    @property
+    def primary_user(self) -> UserID:
+        return self.db_instance.primary_user
+
+    @primary_user.setter
+    def primary_user(self, value: UserID) -> None:
+        self.db_instance.primary_user = value
diff --git a/maubot/plugin_base.py b/maubot/plugin_base.py
new file mode 100644
index 0000000..489352a
--- /dev/null
+++ b/maubot/plugin_base.py
@@ -0,0 +1,31 @@
+# maubot - A plugin-based Matrix bot system.
+# Copyright (C) 2018 Tulir Asokan
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+from typing import TYPE_CHECKING
+from abc import ABC
+
+if TYPE_CHECKING:
+    from mautrix import Client as MatrixClient
+
+
+class Plugin(ABC):
+    def __init__(self, client: 'MatrixClient') -> None:
+        self.client = client
+
+    async def start(self) -> None:
+        pass
+
+    async def stop(self) -> None:
+        pass
diff --git a/setup.py b/setup.py
index 6f467be..ca44f69 100644
--- a/setup.py
+++ b/setup.py
@@ -1,5 +1,10 @@
 import setuptools
-from maubot import __version__
+import os
+
+path = os.path.join(os.path.abspath(os.path.dirname(__file__)), "maubot", "__meta__.py")
+__version__ = "UNKNOWN"
+with open(path) as f:
+    exec(f.read())
 
 setuptools.setup(
     name="maubot",