diff --git a/src/_repobee/config.py b/src/_repobee/config.py
index 1a1b194..59aabe2 100644
--- a/src/_repobee/config.py
+++ b/src/_repobee/config.py
@@ -11,7 +11,7 @@ Contains the code required for pre-configuring user interfaces.
 import os
 import pathlib
 import configparser
-from typing import Union, List, Mapping, Optional
+from typing import Union, List, Mapping
 
 import daiquiri
 import repobee_plug as plug
@@ -137,21 +137,8 @@ def get_all_tasks() -> List[plug.Task]:
     return plug.manager.hook.setup_task() + plug.manager.hook.clone_task()
 
 
-def _fetch_token() -> Optional[str]:
-    token = os.getenv(constants.TOKEN_ENV)
-    token_from_old = os.getenv(constants.TOKEN_ENV_OLD)
-    if token_from_old:
-        LOGGER.warning(
-            "The {} environment variable has been deprecated, "
-            "use {} instead".format(
-                constants.TOKEN_ENV_OLD, constants.TOKEN_ENV
-            )
-        )
-    return token or token_from_old
-
-
 def _read_defaults(config_file: pathlib.Path) -> dict:
-    token = _fetch_token()
+    token = os.getenv(constants.TOKEN_ENV)
     if not config_file.is_file():
         return {} if not token else dict(token=token)
     defaults = dict(_read_config(config_file)[constants.DEFAULTS_SECTION_HDR])
diff --git a/src/_repobee/constants.py b/src/_repobee/constants.py
index 5a55a27..a174027 100644
--- a/src/_repobee/constants.py
+++ b/src/_repobee/constants.py
@@ -39,4 +39,3 @@ ORDERED_CONFIGURABLE_ARGS = (
 CONFIGURABLE_ARGS = set(ORDERED_CONFIGURABLE_ARGS)
 
 TOKEN_ENV = "REPOBEE_TOKEN"
-TOKEN_ENV_OLD = "REPOBEE_OAUTH"
diff --git a/src/_repobee/main.py b/src/_repobee/main.py
index 8b994a6..b51af81 100644
--- a/src/_repobee/main.py
+++ b/src/_repobee/main.py
@@ -57,7 +57,7 @@ def main(sys_args: List[str]):
                 parsed_preparser_args.plug
                 or config.get_plugin_names(config_file)
             ) or []
-            plugin.initialize_plugins(plugin_names)
+            plugin.initialize_plugins(plugin_names, allow_filepath=True)
 
         config.execute_config_hooks(config_file)
         ext_commands = plug.manager.hook.create_extension_command()
diff --git a/src/_repobee/plugin.py b/src/_repobee/plugin.py
index 2fff203..cc3f7ca 100644
--- a/src/_repobee/plugin.py
+++ b/src/_repobee/plugin.py
@@ -14,6 +14,9 @@ import tempfile
 import pkgutil
 import pathlib
 import importlib
+import hashlib
+import os
+import sys
 from types import ModuleType
 from typing import List, Optional, Iterable, Mapping, Union
 
@@ -39,7 +42,9 @@ def _external_plugin_qualname(plugin_name):
 
 
 def load_plugin_modules(
-    plugin_names: Iterable[str], allow_qualified: bool = False
+    plugin_names: Iterable[str],
+    allow_qualified: bool = False,
+    allow_filepath: bool = False,
 ) -> List[ModuleType]:
     """Load the given plugins. Plugins are loaded such that they are executed
     in the same order that they are specified in the plugin_names list.
@@ -56,18 +61,16 @@ def load_plugin_modules(
         # import nr 2
         from repobee_javac import javac
 
-    If ``allow_qualified`` is True, an additional import using the provided
-    plugin names as-is is also attempted.
-
-    .. code-block:: python
-
         # import nr 3 (only if allow_qualified)
         import javac
 
+        # import nr 4 (only if allow_filepath)
+        # Dynamically import using the name as a filepath
+
     Args:
         plugin_names: A list of plugin names.
-        allow_qualified: If True, attempts to import modules using the plugin
-            names as qualified paths.
+        allow_qualified: Allow the plugin to be specified by a qualified name.
+        allow_filepath: Allows the plugin to be specified as a filepath.
     Returns:
         a list of loaded modules.
     """
@@ -79,6 +82,7 @@ def load_plugin_modules(
             _try_load_module(_plugin_qualname(name))
             or _try_load_module(_external_plugin_qualname(name))
             or (allow_qualified and _try_load_module(name))
+            or (allow_filepath and _try_load_module_from_filepath(name))
         )
         if not plug_mod:
             msg = "failed to load plugin module " + name
@@ -87,6 +91,30 @@ def load_plugin_modules(
     return loaded_modules
 
 
+def _try_load_module_from_filepath(path: str) -> Optional[ModuleType]:
+    """Try to load a module from the specified filepath.
+
+    Adapted from code by Sebastian Rittau (https://stackoverflow.com/a/67692).
+
+    Args:
+        path: A path to a Python module.
+    Returns:
+        The module if loaded successfully, or None if there was no module at
+        the path.
+    """
+    package_name = f"_{hashlib.sha1(path.encode(sys.getdefaultencoding()))}"
+    module_name = pathlib.Path(path).stem
+    qualname = f"{package_name}.{module_name}"
+    spec = importlib.util.spec_from_file_location(qualname, path)
+    if not spec:
+        return None
+
+    mod = importlib.util.module_from_spec(spec)
+    spec.loader.exec_module(mod)
+
+    return mod
+
+
 def _try_load_module(qualname: str) -> Optional[ModuleType]:
     """Try to load a module.
 
@@ -208,7 +236,9 @@ def try_register_plugin(
 
 
 def initialize_plugins(
-    plugin_names: List[str] = None, allow_qualified: bool = False,
+    plugin_names: List[str] = None,
+    allow_qualified: bool = False,
+    allow_filepath: bool = False,
 ) -> List[Union[ModuleType, type]]:
     """Load and register plugins.
 
@@ -216,18 +246,23 @@ def initialize_plugins(
         plugin_names: An optional list of plugin names that overrides the
             configuration file's plugins.
         allow_qualified: Allows the plugin names to be qualified.
+        allow_filepath: Allows the plugin to be specified as a filepath.
     Returns:
         A list of registered modules and classes.
     Raises:
         :py:class:`_repobee.exception.PluginLoadError`
     """
+    if not allow_filepath:
+        _check_no_filepaths(plugin_names)
     if not allow_qualified:
         _check_no_qualified_names(plugin_names)
 
     registered_plugins = plug.manager.get_plugins()
     plug_modules = [
         p
-        for p in load_plugin_modules(plugin_names, allow_qualified)
+        for p in load_plugin_modules(
+            plugin_names, allow_qualified, allow_filepath
+        )
         if p not in registered_plugins
     ]
     registered = register_plugins(plug_modules)
@@ -235,8 +270,20 @@ def initialize_plugins(
     return registered
 
 
+def _is_filepath(name: str) -> bool:
+    return os.pathsep in name or os.path.exists(name)
+
+
+def _check_no_filepaths(names: List[str]):
+    filepaths = [name for name in names if _is_filepath(name)]
+    if filepaths:
+        raise exception.PluginLoadError(f"Filepaths not allowed: {filepaths}")
+
+
 def _check_no_qualified_names(names: List[str]):
-    qualified_names = [name for name in names if "." in name]
+    qualified_names = [
+        name for name in names if "." in name and not _is_filepath(name)
+    ]
     if qualified_names:
         raise exception.PluginLoadError(
             f"Qualified names not allowed: {qualified_names}"
@@ -244,9 +291,18 @@ def _check_no_qualified_names(names: List[str]):
 
 
 def resolve_plugin_version(plugin_module: ModuleType) -> Optional[str]:
-    """Return the version of the top-level package containing the plugin, or
-    None if it is not defined.
+    """Return the version of this plugin. Tries to resolve the version by
+    first checking if the plugin module itself has a ``__version__``
+    attribute, and then the top level package.
+
+    Args:
+        plugin_module: A plugin module.
+    Returns:
+        The version if found, otherwise None.
     """
+    if hasattr(plugin_module, "__version__"):
+        return plugin_module.__version__
+
     pkg_name = plugin_module.__package__.split(".")[0]
     pkg_module = _try_load_module(pkg_name)
     return (

diff --git a/tests/unit_tests/repobee/conftest.py b/tests/unit_tests/repobee/conftest.py
index 8d004ed..5b8d481 100644
--- a/tests/unit_tests/repobee/conftest.py
+++ b/tests/unit_tests/repobee/conftest.py
@@ -21,7 +21,6 @@ import _repobee  # noqa: E402
 
 EXPECTED_ENV_VARIABLES = [
     _repobee.constants.TOKEN_ENV,
-    _repobee.constants.TOKEN_ENV_OLD,
     "REPOBEE_NO_VERIFY_SSL",
 ]
 
diff --git a/tests/unit_tests/repobee/test_config.py b/tests/unit_tests/repobee/test_config.py
index 7466b82..7e88fa5 100644
--- a/tests/unit_tests/repobee/test_config.py
+++ b/tests/unit_tests/repobee/test_config.py
@@ -55,23 +55,6 @@ class TestGetConfiguredDefaults:
         defaults = config.get_configured_defaults(str(config_mock))
         assert defaults["token"] == constants.TOKEN
 
-    @pytest.mark.skipif(
-        "_repobee.__version__ >= '3.0.0'",
-        msg="Old token should have been removed",
-    )
-    def test_deprecated_token_env(self, config_mock, mock_getenv):
-        token = "superdupertoken"
-
-        def _env(name):
-            if name == _repobee.constants.TOKEN_ENV_OLD:
-                return token
-            return None
-
-        mock_getenv.side_effect = _env
-
-        defaults = config.get_configured_defaults(str(config_mock))
-        assert defaults["token"] == token
-
     def test_get_configured_defaults_raises_on_invalid_keys(
         self, empty_config_mock, students_file
     ):
diff --git a/tests/unit_tests/repobee/test_main.py b/tests/unit_tests/repobee/test_main.py
index 5056633..fcbabc0 100644
--- a/tests/unit_tests/repobee/test_main.py
+++ b/tests/unit_tests/repobee/test_main.py
@@ -57,7 +57,7 @@ def api_instance_mock(mocker):
 
 @pytest.fixture
 def init_plugins_mock(mocker):
-    def init_plugins(plugs=None, allow_qualified=False):
+    def init_plugins(plugs=None, allow_qualified=False, allow_filepath=False):
         list(map(module, plugs or []))
 
     return mocker.patch(
@@ -159,7 +159,7 @@ def test_plugins_args(
 
     init_plugins_mock.assert_has_calls(
         [
-            call(["javac", "pylint"]),
+            call(["javac", "pylint"], allow_filepath=True),
             call(DEFAULT_PLUGIN_NAMES, allow_qualified=True),
         ],
         any_order=True,
@@ -223,7 +223,7 @@ def test_configured_plugins_are_loaded(
 
     init_plugins_mock.assert_has_calls(
         [
-            call(["javac", "pylint"]),
+            call(["javac", "pylint"], allow_filepath=True),
             call(DEFAULT_PLUGIN_NAMES, allow_qualified=True),
         ],
         any_order=True,
@@ -245,7 +245,7 @@ def test_plugin_with_subparser_name(
 
     init_plugins_mock.assert_has_calls(
         [
-            call(["javac", "clone"]),
+            call(["javac", "clone"], allow_filepath=True),
             call(DEFAULT_PLUGIN_NAMES, allow_qualified=True),
         ],
         any_order=True,
@@ -287,7 +287,10 @@ def test_invalid_plug_options(dispatch_command_mock, init_plugins_mock):
         main.main(sys_args)
 
     init_plugins_mock.assert_has_calls(
-        [call(["javac"]), call(DEFAULT_PLUGIN_NAMES, allow_qualified=True)],
+        [
+            call(["javac"], allow_filepath=True),
+            call(DEFAULT_PLUGIN_NAMES, allow_qualified=True),
+        ],
         any_order=True,
     )
     assert not dispatch_command_mock.called
diff --git a/tests/unit_tests/repobee/test_plugin.py b/tests/unit_tests/repobee/test_plugin.py
index 3a2f2ba..9656ae2 100644
--- a/tests/unit_tests/repobee/test_plugin.py
+++ b/tests/unit_tests/repobee/test_plugin.py
@@ -6,6 +6,7 @@
         installed any other plugins, tests in here may fail unexpectedly
         without anything actually being wrong.
 """
+import shutil
 import pathlib
 import tempfile
 import types
@@ -246,3 +247,39 @@ class TestInitializePlugins:
             plugin.initialize_plugins([qualname])
 
         assert "Qualified names not allowed" in str(exc_info.value)
+
+    def test_raises_on_filepath_by_default(self, tmpdir):
+        plugin_file = pathlib.Path(str(tmpdir)) / "pylint.py"
+        shutil.copy(_repobee.ext.javac.__file__, str(plugin_file))
+
+        with pytest.raises(exception.PluginLoadError) as exc_info:
+            plugin.initialize_plugins([str(plugin_file)])
+
+        assert "Filepaths not allowed" in str(exc_info.value)
+
+    def test_initialize_from_filepath_filepath(self, tmpdir):
+        """Test initializing a plugin that's specified by a filepath."""
+        plugin_file = pathlib.Path(str(tmpdir)) / "pylint.py"
+        shutil.copy(_repobee.ext.pylint.__file__, str(plugin_file))
+
+        initialized_plugins = plugin.initialize_plugins(
+            [str(plugin_file)], allow_filepath=True
+        )
+
+        assert len(initialized_plugins) == 1
+        assert initialized_plugins[0].__file__ == str(plugin_file)
+
+    def test_raises_when_filepath_is_not_python_module(self, tmpdir):
+        not_a_python_module = pathlib.Path(str(tmpdir)) / "some_file.txt"
+        not_a_python_module.write_text(
+            "This is definitely\nnot a Python module"
+        )
+
+        with pytest.raises(exception.PluginLoadError) as exc_info:
+            plugin.initialize_plugins(
+                [str(not_a_python_module)], allow_filepath=True
+            )
+
+        assert f"failed to load plugin module {not_a_python_module}" in str(
+            exc_info.value
+        )

Make it possible to write a local single-file plugin
In theory, there's nothing stopping us from supporting local single-file plugins, as it's super easy to load a module given its filepath. These files also wouldn't need to follow any form of convention (other than defining hook implementations). Just as an example, imagine I have written the `javac.py` plugin and it's located at `/home/slarse/javac.py`. Then, I run RepoBee like so:

```
$ repobee --plug /home/slarse/javac.py clone ...
```

Making this work is extremely easy: when loading plugins, just check if the plugin specified is a local file. It will massively lower the bar for creating plugins.
tests/unit_tests/repobee/test_config.py::TestGetConfiguredDefaults::test_get_configured_defaults_no_config_file tests/unit_tests/repobee/test_config.py::TestGetConfiguredDefaults::test_get_configured_defaults_empty_file tests/unit_tests/repobee/test_config.py::TestGetConfiguredDefaults::test_token_in_env_variable_overrides_configuration_file tests/unit_tests/repobee/test_config.py::TestGetConfiguredDefaults::test_get_configured_defaults_raises_on_invalid_keys tests/unit_tests/repobee/test_config.py::TestGetConfiguredDefaults::test_get_configured_defaults_raises_on_missing_header tests/unit_tests/repobee/test_config.py::TestCheckConfigIntegrity::test_with_well_formed_config tests/unit_tests/repobee/test_config.py::TestCheckConfigIntegrity::test_with_invalid_defaults_key_raises tests/unit_tests/repobee/test_config.py::TestCheckConfigIntegrity::test_with_valid_but_malformed_default_args_raises tests/unit_tests/repobee/test_main.py::test_plugins_args tests/unit_tests/repobee/test_main.py::test_configured_plugins_are_loaded tests/unit_tests/repobee/test_main.py::test_plugin_with_subparser_name tests/unit_tests/repobee/test_main.py::test_invalid_plug_options tests/unit_tests/repobee/test_main.py::test_show_config_custom_config tests/unit_tests/repobee/test_plugin.py::TestInitializePlugins::test_raises_on_filepath_by_default tests/unit_tests/repobee/test_plugin.py::TestInitializePlugins::test_initialize_from_filepath_filepath tests/unit_tests/repobee/test_plugin.py::TestInitializePlugins::test_raises_when_filepath_is_not_python_module
tests/unit_tests/repobee/test_config.py::TestGetConfiguredDefaults::test_get_configured_defaults_reads_full_config tests/unit_tests/repobee/test_config.py::TestGetPluginNames::test_with_full_config tests/unit_tests/repobee/test_config.py::TestGetPluginNames::test_with_only_plugins[javac,pylint-expected_plugins0] tests/unit_tests/repobee/test_config.py::TestGetPluginNames::test_with_only_plugins[javac, tests/unit_tests/repobee/test_config.py::TestGetPluginNames::test_with_only_plugins[javac-expected_plugins2] tests/unit_tests/repobee/test_config.py::TestGetPluginNames::test_with_only_plugins[-expected_plugins3] tests/unit_tests/repobee/test_config.py::TestExecuteConfigHooks::test_with_no_config_file tests/unit_tests/repobee/test_config.py::TestExecuteConfigHooks::test_with_config_file tests/unit_tests/repobee/test_config.py::TestCheckConfigIntegrity::test_with_well_formed_plugin_options tests/unit_tests/repobee/test_config.py::TestCheckConfigIntegrity::test_with_no_config_file_raises tests/unit_tests/repobee/test_main.py::test_happy_path tests/unit_tests/repobee/test_main.py::test_exit_status_1_on_exception_in_parsing tests/unit_tests/repobee/test_main.py::test_exit_status_1_on_exception_in_handling_parsed_args tests/unit_tests/repobee/test_main.py::test_no_plugins_arg tests/unit_tests/repobee/test_main.py::test_no_plugins_with_configured_plugins tests/unit_tests/repobee/test_main.py::test_plug_arg_incompatible_with_no_plugins tests/unit_tests/repobee/test_main.py::test_does_not_raise_on_exception_in_dispatch tests/unit_tests/repobee/test_main.py::test_logs_traceback_on_exception_in_dispatch_if_traceback tests/unit_tests/repobee/test_main.py::test_show_all_opts_correctly_separated tests/unit_tests/repobee/test_main.py::test_non_zero_exit_status_on_exception tests/unit_tests/repobee/test_plugin.py::TestLoadPluginModules::test_load_default_plugins tests/unit_tests/repobee/test_plugin.py::TestLoadPluginModules::test_load_bundled_plugins tests/unit_tests/repobee/test_plugin.py::TestLoadPluginModules::test_load_no_plugins tests/unit_tests/repobee/test_plugin.py::TestLoadPluginModules::test_raises_when_loading_invalid_module tests/unit_tests/repobee/test_plugin.py::TestLoadPluginModules::test_raises_when_loading_default_plugins_without_allow_qualified tests/unit_tests/repobee/test_plugin.py::TestRegisterPlugins::test_register_module tests/unit_tests/repobee/test_plugin.py::TestRegisterPlugins::test_register_module_with_plugin_class tests/unit_tests/repobee/test_plugin.py::TestRegisterPlugins::test_register_modules_and_classes tests/unit_tests/repobee/test_plugin.py::TestTryRegisterPlugin::test_modules_unregistered_after_success tests/unit_tests/repobee/test_plugin.py::TestTryRegisterPlugin::test_modules_and_classes_unregistered_after_success tests/unit_tests/repobee/test_plugin.py::TestTryRegisterPlugin::test_does_not_unregister_unrelated_plugins tests/unit_tests/repobee/test_plugin.py::TestTryRegisterPlugin::test_modules_unregistered_after_fail tests/unit_tests/repobee/test_plugin.py::TestTryRegisterPlugin::test_fails_if_classes_not_specified tests/unit_tests/repobee/test_plugin.py::TestTasks::test_tasks_run_on_repo_copies_by_default tests/unit_tests/repobee/test_plugin.py::TestInitializePlugins::test_deprecation_warning_is_emitted_for_deprecated_hook tests/unit_tests/repobee/test_plugin.py::TestInitializePlugins::test_raises_on_qualified_names_by_default