diff --git a/swh/foo/bar.py b/conftest.py
rename from swh/foo/bar.py
rename to conftest.py
--- a/swh/foo/bar.py
+++ b/conftest.py
@@ -1,4 +1,9 @@
-# Copyright (C) 2019  The Software Heritage developers
+# Copyright (C) 2019-2020  The Software Heritage developers
 # See the AUTHORS file at the top-level directory of this distribution
 # License: GNU General Public License version 3, or any later version
 # See top-level LICENSE file for more information
+
+pytest_plugins = [
+    "swh.storage.pytest_plugin",
+    "swh.loader.pytest_plugin",
+]
diff --git a/docs/README.rst b/docs/README.rst
--- a/docs/README.rst
+++ b/docs/README.rst
@@ -1,4 +1,5 @@
-Software Heritage - Python module template
-==========================================
+Software Heritage - Metadata Fetchers
+=====================================
 
-Python module template, used as skeleton to create new modules.
+This package hooks into the loaders, and loads extrinsic metadata at the same time
+code artifacts are retrieved.
diff --git a/docs/index.rst b/docs/index.rst
--- a/docs/index.rst
+++ b/docs/index.rst
@@ -1,4 +1,4 @@
-.. _swh-py-template:
+.. _swh-loader-metadata:
 
 .. include:: README.rst
 
diff --git a/mypy.ini b/mypy.ini
--- a/mypy.ini
+++ b/mypy.ini
@@ -5,6 +5,9 @@
 
 # 3rd party libraries without stubs (yet)
 
+[mypy-iso8601.*]
+ignore_missing_imports = True
+
 [mypy-pkg_resources.*]
 ignore_missing_imports = True
 
diff --git a/requirements-swh.txt b/requirements-swh.txt
--- a/requirements-swh.txt
+++ b/requirements-swh.txt
@@ -1,2 +1,4 @@
-# Add here internal Software Heritage dependencies, one per line.
 swh.core[http] >= 0.3  # [http] is required by swh.core.pytest_plugin
+swh.lister >= 2.9.0
+swh.loader.core >= 3.1.0
+swh.storage >= 0.29.0
diff --git a/requirements-test.txt b/requirements-test.txt
--- a/requirements-test.txt
+++ b/requirements-test.txt
@@ -1 +1,7 @@
 pytest
+pytest-mock
+requests_mock
+types-requests
+types-PyYAML
+
+swh-storage[testing]
diff --git a/setup.py b/setup.py
--- a/setup.py
+++ b/setup.py
@@ -36,18 +36,15 @@
     return requirements
 
 
-# Edit this part to match your module, replace foo by its name
-# Full sample:
-#   https://forge.softwareheritage.org/diffusion/DCORE/browse/master/setup.py
 setup(
-    name="swh.foo",  # example: swh.loader.pypi
-    description="Software Heritage <Module's intent>",
+    name="swh.loader.metadata",
+    description="Software Heritage Extrinsic Metadata Fetchers",
     long_description=long_description,
     long_description_content_type="text/x-rst",
     python_requires=">=3.7",
     author="Software Heritage developers",
     author_email="swh-devel@inria.fr",
-    url="https://forge.softwareheritage.org/diffusion/<module-git-code>",
+    url="https://forge.softwareheritage.org/diffusion/swh-loader-metadata",
     packages=find_packages(),  # packages's modules
     install_requires=parse_requirements(None, "swh"),
     tests_require=parse_requirements("test"),
@@ -56,8 +53,8 @@
     extras_require={"testing": parse_requirements("test")},
     include_package_data=True,
     entry_points="""
-        [swh.cli.subcommands]
-        foo=swh.foo.cli
+        [swh.loader.metadata]
+        github=swh.loader.metadata.github:GitHubMetadataFetcher
     """,
     classifiers=[
         "Programming Language :: Python :: 3",
@@ -69,7 +66,7 @@
     project_urls={
         "Bug Reports": "https://forge.softwareheritage.org/maniphest",
         "Funding": "https://www.softwareheritage.org/donate",
-        "Source": "https://forge.softwareheritage.org/source/swh-<module>",
-        "Documentation": "https://docs.softwareheritage.org/devel/swh-<module>/",
+        "Source": "https://forge.softwareheritage.org/source/swh-loader-metadata",
+        "Documentation": "https://docs.softwareheritage.org/devel/swh-loader-metadata/",
     },
 )
diff --git a/swh/foo/cli.py b/swh/foo/cli.py
deleted file mode 100644
--- a/swh/foo/cli.py
+++ /dev/null
@@ -1,18 +0,0 @@
-import click
-
-from swh.core.cli import CONTEXT_SETTINGS
-from swh.core.cli import swh as swh_cli_group
-
-
-@swh_cli_group.group(name="foo", context_settings=CONTEXT_SETTINGS)
-@click.pass_context
-def foo_cli_group(ctx):
-    """Foo main command."""
-
-
-@foo_cli_group.command()
-@click.option("--bar", help="Something")
-@click.pass_context
-def bar(ctx, bar):
-    """Do something."""
-    click.echo("bar")
diff --git a/swh/foo/tests/__init__.py b/swh/foo/tests/__init__.py
deleted file mode 100644
diff --git a/swh/foo/tests/test_nothing.py b/swh/foo/tests/test_nothing.py
deleted file mode 100644
--- a/swh/foo/tests/test_nothing.py
+++ /dev/null
@@ -1,3 +0,0 @@
-def test_nothing():
-    # Placeholder; remove this when we add actual tests
-    pass
diff --git a/swh/loader/__init__.py b/swh/loader/__init__.py
new file mode 100644
--- /dev/null
+++ b/swh/loader/__init__.py
@@ -0,0 +1,3 @@
+from pkgutil import extend_path
+
+__path__ = extend_path(__path__, __name__)
diff --git a/swh/loader/metadata/__init__.py b/swh/loader/metadata/__init__.py
new file mode 100644
--- /dev/null
+++ b/swh/loader/metadata/__init__.py
@@ -0,0 +1,15 @@
+# Copyright (C) 2019-2022  The Software Heritage developers
+# See the AUTHORS file at the top-level directory of this distribution
+# License: GNU General Public License version 3, or any later version
+# See top-level LICENSE file for more information
+
+import pkg_resources
+
+try:
+    __version__ = pkg_resources.get_distribution("swh.loader.metadata").version
+except pkg_resources.DistributionNotFound:
+    __version__ = "devel"
+
+
+USER_AGENT_TEMPLATE = "Software Heritage Metadata Loader (%s)"
+USER_AGENT = USER_AGENT_TEMPLATE % __version__
diff --git a/swh/foo/bar.py b/swh/loader/metadata/bar.py
rename from swh/foo/bar.py
rename to swh/loader/metadata/bar.py
diff --git a/swh/loader/metadata/base.py b/swh/loader/metadata/base.py
new file mode 100644
--- /dev/null
+++ b/swh/loader/metadata/base.py
@@ -0,0 +1,184 @@
+# Copyright (C) 2020-2022 The Software Heritage developers
+# See the AUTHORS file at the top-level directory of this distribution
+# License: GNU General Public License version 3, or any later version
+# See top-level LICENSE file for more information
+
+"""Base module for all metadata fetchers, which are called by the Git loader
+to get metadata from forges on origins being loaded."""
+
+import datetime
+import sys
+from typing import TYPE_CHECKING, Dict, List, Optional, Set, Tuple, Type
+import urllib.parse
+
+import requests
+
+from swh.model.model import (
+    MetadataAuthority,
+    MetadataAuthorityType,
+    MetadataFetcher,
+    Origin,
+    RawExtrinsicMetadata,
+)
+
+CredentialsType = Optional[Dict[str, Dict[str, List[Dict[str, str]]]]]
+
+
+class InvalidOrigin(Exception):
+    pass
+
+
+def now() -> datetime.datetime:
+    # Used by tests for mocking
+    return datetime.datetime.now(tz=datetime.timezone.utc)
+
+
+class BaseMetadataFetcher:
+    """The base class for a Software Heritage metadata fetchers
+
+    Fetchers are hooks used by loader to retrieve extrinsic metadata from
+    forges before archiving repositories.
+
+    Each fetcher handles a specific type of forge (not VCS); each fetcher
+    class generally matches a lister class, as they use the same APIs.
+
+    Args:
+      origin: the origin to retrieve metadata from
+      credentials: This is the same format as for :class:`swh.lister.pattern.Lister`:
+        dictionary of credentials for all fetchers. The first level
+        identifies the fetcher's name, the second level the lister
+        instance. The final level is a list of dicts containing the
+        expected credentials for the given instance of that fetcher.
+      session: optional HTTP session to use to send HTTP requests
+    """
+
+    FETCHER_NAME: str
+    """The config-friendly name of this fetcher, used to retrieve the first
+    level of credentials."""
+
+    SUPPORTED_LISTERS: Set[str]
+    """Set of forge types this metadata fetcher supports. The type names are the same
+    as the names used by listers themselves.
+
+    Generally, fetchers have a one-to-one matching with listers, in which case
+    this is set of ``{FETCHER_NAME}``.
+    """
+
+    def __init__(
+        self,
+        origin: Origin,
+        credentials: CredentialsType,
+        lister_name: str,
+        lister_instance_name: str,
+    ):
+        if self.FETCHER_NAME is None:
+            raise NotImplementedError(f"{self.__class__.__name__}.FETCHER_NAME")
+        self.origin = origin
+        self._check_origin()
+        self._origin_metadata_objects: Optional[List[RawExtrinsicMetadata]] = None
+        self._session: Optional[requests.Session] = None
+
+        # Both names do not *have* to match, but they all do for now.
+        assert lister_name == self.FETCHER_NAME
+
+        self.credentials = list(
+            (credentials or {}).get(lister_name, {}).get(lister_instance_name, [])
+        )
+
+    def _make_session(self) -> requests.Session:
+        session = requests.Session()
+        fetcher = self._metadata_fetcher()
+        user_agent = (
+            f"Software Heritage Metadata Fetcher ({fetcher.name} {fetcher.version})"
+        )
+        session.headers["User-Agent"] = user_agent
+        return session
+
+    def session(self) -> requests.Session:
+        if self._session is None:
+            self._session = self._make_session()
+        return self._session
+
+    def _check_origin(self) -> bool:
+        """Raise :exc:`InvalidOrigin` if the origin does not belong to the supported
+        forge types of this fetcher."""
+        raise NotImplementedError(f"{self.__class__.__name__}._check_origin")
+
+    def _get_origin_metadata_bytes(self) -> List[Tuple[str, bytes]]:
+        """Return pairs of ``(format, metadata)``, used to build
+        :class:`swh.model.model.RawExtrinsicMetadata` objects."""
+        raise NotImplementedError(
+            f"{self.__class__.__name__}.get_origin_metadata_bytes"
+        )
+
+    def _metadata_authority(self) -> MetadataAuthority:
+        """Return information about the metadata authority that issued metadata
+        we extract from the given origin"""
+        (scheme, netloc, *_) = urllib.parse.urlsplit(self.origin.url)
+
+        assert scheme and netloc, self.origin.url
+
+        # A good default that should work for most, if not all, forges
+        forge_url = urllib.parse.urlunsplit(("https", netloc, "", "", ""))
+        return MetadataAuthority(
+            url=forge_url,
+            type=MetadataAuthorityType.FORGE,
+        )
+
+    @classmethod
+    def _get_package_version(cls) -> str:
+        """Return the version of the current loader."""
+        module_name = cls.__module__ or ""
+        module_name_parts = module_name.split(".")
+
+        # Iterate rootward through the package hierarchy until we find a parent of this
+        # loader's module with a __version__ attribute.
+        for prefix_size in range(len(module_name_parts), 0, -1):
+            package_name = ".".join(module_name_parts[0:prefix_size])
+            module = sys.modules[package_name]
+            if hasattr(module, "__version__"):
+                return module.__version__
+
+        # If this fetcher's class has no parent package with a __version__,
+        # it should implement it itself.
+        raise NotImplementedError(
+            f"Could not dynamically find the version of {module_name}."
+        )
+
+    @classmethod
+    def _metadata_fetcher(cls) -> MetadataFetcher:
+        """Return information about this metadata fetcher"""
+        return MetadataFetcher(
+            name=cls.__module__,
+            version=cls._get_package_version(),
+        )
+
+    def get_origin_metadata(self) -> List[RawExtrinsicMetadata]:
+        """Return a list of metadata objects for the given origin."""
+        if self._origin_metadata_objects is None:
+            self._origin_metadata_objects = []
+            for (format_, metadata_bytes) in self._get_origin_metadata_bytes():
+                self._origin_metadata_objects.append(
+                    RawExtrinsicMetadata(
+                        target=self.origin.swhid(),
+                        discovery_date=now(),
+                        authority=self._metadata_authority(),
+                        fetcher=self._metadata_fetcher(),
+                        format=format_,
+                        metadata=metadata_bytes,
+                    )
+                )
+
+        return self._origin_metadata_objects
+
+
+if TYPE_CHECKING:
+    # Makes mypy check BaseMetadataFetcher follows the MetadataFetcherProtocol
+    def _f() -> None:
+        from swh.loader.core.metadata_fetchers import MetadataFetcherProtocol
+
+        base_metadata_fetcher: Type[MetadataFetcherProtocol]
+        base_metadata_fetcher = BaseMetadataFetcher
+        print(base_metadata_fetcher)
+
+    del _f
diff --git a/swh/loader/metadata/github.py b/swh/loader/metadata/github.py
new file mode 100644
--- /dev/null
+++ b/swh/loader/metadata/github.py
@@ -0,0 +1,69 @@
+# Copyright (C) 2022 The Software Heritage developers
+# See the AUTHORS file at the top-level directory of this distribution
+# License: GNU General Public License version 3, or any later version
+# See top-level LICENSE file for more information
+
+"""Metadata fetcher for GitHub."""
+
+import re
+from typing import List, Optional, Tuple
+import urllib.parse
+
+from swh.lister.github.utils import GitHubSession
+
+from . import USER_AGENT
+from .base import BaseMetadataFetcher, InvalidOrigin
+
+HTTP_ACCEPT = "application/vnd.github.v3+json"
+"""HTTP header sent on all API requests to GitHub."""
+
+# The format is defined by a well-understood MIME type; we might as well use that.
+METADATA_FORMAT = HTTP_ACCEPT
+"""Value of the ``format`` field of produced
+:class:`swh.model.model.RawExtrinsicMetadata` objects."""
+
+_API_URL = "https://api.github.com/repos{path}"
+
+
+class GitHubMetadataFetcher(BaseMetadataFetcher):
+    FETCHER_NAME = "github"
+    SUPPORTED_LISTERS = {"github"}
+
+    _github_session: Optional[GitHubSession] = None
+
+    def github_session(self) -> GitHubSession:
+        if self._github_session is None:
+            self._github_session = GitHubSession(
+                user_agent=USER_AGENT, credentials=self.credentials
+            )
+        return self._github_session
+
+    def _check_origin(self):
+        (scheme, netloc, path, query, fragment) = urllib.parse.urlsplit(self.origin.url)
+        if netloc != "github.com":
+            # TODO: relax this check when we support self-hosted GitHub instances
+            raise InvalidOrigin(f"netloc should be 'github.com', not '{netloc}'")
+
+        if scheme != "https" or not re.match(r"/[^\s/]+/[^\s/]+", path):
+            raise InvalidOrigin(f"Unsupported github.com URL: {self.origin.url}")
+
+        if query != "" or fragment != "":
+            raise InvalidOrigin(
+                f"Unexpected end query or fragment in github.com URL: {self.origin.url}"
+            )
+
+    def _get_origin_metadata_bytes(self) -> List[Tuple[str, bytes]]:
+        (scheme, netloc, path, query, fragment) = urllib.parse.urlsplit(self.origin.url)
+        response = self.github_session().request(_API_URL.format(path=path))
+        if response.status_code != 200:
+            # TODO: retry
+            return []
+
+        metadata_bytes = response.content
+
+        # TODO?: strip API hyperlinks from metadata_bytes to save space?
+        # They take 10KB for every repo, or 1KB when compressed by the database server.
+        # This means processing metadata_bytes and changing the format, instead of
+        # archiving verbatim, though.
+
+        return [(METADATA_FORMAT, metadata_bytes)]
diff --git a/swh/foo/py.typed b/swh/loader/metadata/py.typed
rename from swh/foo/py.typed
rename to swh/loader/metadata/py.typed
diff --git a/swh/foo/__init__.py b/swh/loader/metadata/tests/__init__.py
rename from swh/foo/__init__.py
rename to swh/loader/metadata/tests/__init__.py
diff --git a/swh/loader/metadata/tests/data/https_api.github.com/repos_octocat_Hello-World b/swh/loader/metadata/tests/data/https_api.github.com/repos_octocat_Hello-World
new file mode 100644
--- /dev/null
+++ b/swh/loader/metadata/tests/data/https_api.github.com/repos_octocat_Hello-World
@@ -0,0 +1,103 @@
+{
+  "id": 1296269,
+  "node_id": "MDEwOlJlcG9zaXRvcnkxMjk2MjY5",
+  "name": "Hello-World",
+  "full_name": "octocat/Hello-World",
+  "private": false,
+  "owner": {
+    "login": "octocat",
+    "id": 583231,
+    "node_id": "MDQ6VXNlcjU4MzIzMQ==",
+    "avatar_url": "https://avatars.githubusercontent.com/u/583231?v=4",
+    "gravatar_id": "",
+    "url": "https://api.github.com/users/octocat",
+    "html_url": "https://github.com/octocat",
+    "followers_url": "https://api.github.com/users/octocat/followers",
+    "following_url": "https://api.github.com/users/octocat/following{/other_user}",
+    "gists_url": "https://api.github.com/users/octocat/gists{/gist_id}",
+    "starred_url": "https://api.github.com/users/octocat/starred{/owner}{/repo}",
+    "subscriptions_url": "https://api.github.com/users/octocat/subscriptions",
+    "organizations_url": "https://api.github.com/users/octocat/orgs",
+    "repos_url": "https://api.github.com/users/octocat/repos",
+    "events_url": "https://api.github.com/users/octocat/events{/privacy}",
+    "received_events_url": "https://api.github.com/users/octocat/received_events",
+    "type": "User",
+    "site_admin": false
+  },
+  "html_url": "https://github.com/octocat/Hello-World",
+  "description": "My first repository on GitHub!",
+  "fork": false,
+  "url": "https://api.github.com/repos/octocat/Hello-World",
+  "forks_url": "https://api.github.com/repos/octocat/Hello-World/forks",
+  "keys_url": "https://api.github.com/repos/octocat/Hello-World/keys{/key_id}",
+  "collaborators_url": "https://api.github.com/repos/octocat/Hello-World/collaborators{/collaborator}",
+  "teams_url": "https://api.github.com/repos/octocat/Hello-World/teams",
+  "hooks_url": "https://api.github.com/repos/octocat/Hello-World/hooks",
+  "issue_events_url": "https://api.github.com/repos/octocat/Hello-World/issues/events{/number}",
+  "events_url": "https://api.github.com/repos/octocat/Hello-World/events",
+  "assignees_url": "https://api.github.com/repos/octocat/Hello-World/assignees{/user}",
+  "branches_url": "https://api.github.com/repos/octocat/Hello-World/branches{/branch}",
+  "tags_url": "https://api.github.com/repos/octocat/Hello-World/tags",
+  "blobs_url": "https://api.github.com/repos/octocat/Hello-World/git/blobs{/sha}",
+  "git_tags_url": "https://api.github.com/repos/octocat/Hello-World/git/tags{/sha}",
+  "git_refs_url": "https://api.github.com/repos/octocat/Hello-World/git/refs{/sha}",
+  "trees_url": "https://api.github.com/repos/octocat/Hello-World/git/trees{/sha}",
+  "statuses_url": "https://api.github.com/repos/octocat/Hello-World/statuses/{sha}",
+  "languages_url": "https://api.github.com/repos/octocat/Hello-World/languages",
+  "stargazers_url": "https://api.github.com/repos/octocat/Hello-World/stargazers",
+  "contributors_url": "https://api.github.com/repos/octocat/Hello-World/contributors",
+  "subscribers_url": "https://api.github.com/repos/octocat/Hello-World/subscribers",
+  "subscription_url": "https://api.github.com/repos/octocat/Hello-World/subscription",
+  "commits_url": "https://api.github.com/repos/octocat/Hello-World/commits{/sha}",
+  "git_commits_url": "https://api.github.com/repos/octocat/Hello-World/git/commits{/sha}",
+  "comments_url": "https://api.github.com/repos/octocat/Hello-World/comments{/number}",
+  "issue_comment_url": "https://api.github.com/repos/octocat/Hello-World/issues/comments{/number}",
+  "contents_url": "https://api.github.com/repos/octocat/Hello-World/contents/{+path}",
+  "compare_url": "https://api.github.com/repos/octocat/Hello-World/compare/{base}...{head}",
+  "merges_url": "https://api.github.com/repos/octocat/Hello-World/merges",
+  "archive_url": "https://api.github.com/repos/octocat/Hello-World/{archive_format}{/ref}",
+  "downloads_url": "https://api.github.com/repos/octocat/Hello-World/downloads",
+  "issues_url": "https://api.github.com/repos/octocat/Hello-World/issues{/number}",
+  "pulls_url": "https://api.github.com/repos/octocat/Hello-World/pulls{/number}",
+  "milestones_url": "https://api.github.com/repos/octocat/Hello-World/milestones{/number}",
+  "notifications_url": "https://api.github.com/repos/octocat/Hello-World/notifications{?since,all,participating}",
+  "labels_url": "https://api.github.com/repos/octocat/Hello-World/labels{/name}",
+  "releases_url": "https://api.github.com/repos/octocat/Hello-World/releases{/id}",
+  "deployments_url": "https://api.github.com/repos/octocat/Hello-World/deployments",
+  "created_at": "2011-01-26T19:01:12Z",
+  "updated_at": "2022-04-21T05:34:00Z",
+  "pushed_at": "2022-04-15T15:39:28Z",
+  "git_url": "git://github.com/octocat/Hello-World.git",
+  "ssh_url": "git@github.com:octocat/Hello-World.git",
+  "clone_url": "https://github.com/octocat/Hello-World.git",
+  "svn_url": "https://github.com/octocat/Hello-World",
+  "homepage": "",
+  "size": 1,
+  "stargazers_count": 1844,
+  "watchers_count": 1844,
+  "language": null,
+  "has_issues": true,
+  "has_projects": true,
+  "has_downloads": true,
+  "has_wiki": true,
+  "has_pages": false,
+  "forks_count": 1729,
+  "mirror_url": null,
+  "archived": false,
+  "disabled": false,
+  "open_issues_count": 867,
+  "license": null,
+  "allow_forking": true,
+  "is_template": false,
+  "topics": [
+
+  ],
+  "visibility": "public",
+  "forks": 1729,
+  "open_issues": 867,
+  "watchers": 1844,
+  "default_branch": "master",
+  "temp_clone_token": null,
+  "network_count": 1729,
+  "subscribers_count": 1724
+}
diff --git a/swh/loader/metadata/tests/test_base.py b/swh/loader/metadata/tests/test_base.py
new file mode 100644
--- /dev/null
+++ b/swh/loader/metadata/tests/test_base.py
@@ -0,0 +1,108 @@
+# Copyright (C) 2022 The Software Heritage developers
+# See the AUTHORS file at the top-level directory of this distribution
+# License: GNU General Public License version 3, or any later version
+# See top-level LICENSE file for more information
+
+import datetime
+
+import pytest
+
+from swh.loader.core.loader import BaseLoader
+from swh.loader.metadata.base import BaseMetadataFetcher
+from swh.model.model import (
+    MetadataAuthority,
+    MetadataAuthorityType,
+    MetadataFetcher,
+    Origin,
+    RawExtrinsicMetadata,
+)
+import swh.storage.exc
+
+ORIGIN = Origin(url="some-url")
+
+METADATA_AUTHORITY = MetadataAuthority(
+    type=MetadataAuthorityType.FORGE, url="http://example.org/"
+)
+REMD = RawExtrinsicMetadata(
+    target=ORIGIN.swhid(),
+    discovery_date=datetime.datetime.now(tz=datetime.timezone.utc),
+    authority=METADATA_AUTHORITY,
+    fetcher=MetadataFetcher(
+        name="test fetcher",
+        version="0.0.1",
+    ),
+    format="test-format",
+    metadata=b'{"foo": "bar"}',
+)
+
+
+class DummyLoader(BaseLoader):
+    """Base Loader to overload and simplify the base class (technical: to avoid repetition
+    in other *Loader classes)"""
+
+    visit_type = "git"
+
+    def __init__(self, storage, *args, **kwargs):
+        super().__init__(storage, *args, **kwargs)
+
+    def cleanup(self):
+        pass
+
+    def prepare(self, *args, **kwargs):
+        pass
+
+    def fetch_data(self):
+        pass
+
+    def get_snapshot_id(self):
+        return None
+
+    def store_data(self):
+        pass
+
+
+class DummyMetadataFetcher(BaseMetadataFetcher):
+    SUPPORTED_LISTERS = {"fake-lister"}
+
+    def __init__(self, origin, credentials, lister_name, lister_instance_name):
+        pass
+
+    def get_origin_metadata(self):
+        return [REMD]
+
+
+def test_load(swh_storage, mocker):
+    mocker.patch(
+        "swh.loader.core.metadata_fetchers._fetchers",
+        return_value=[DummyMetadataFetcher],
+    )
+
+    loader = DummyLoader(
+        storage=swh_storage,
+        origin_url=ORIGIN.url,
+        lister_name="fake-lister",
+        lister_instance_name="",
+    )
+    loader.load()
+
+    assert swh_storage.raw_extrinsic_metadata_get(
+        ORIGIN.swhid(), METADATA_AUTHORITY
+    ).results == [REMD]
+
+
+def test_load_unknown_lister(swh_storage, mocker):
+    mocker.patch(
+        "swh.loader.core.metadata_fetchers._fetchers",
+        return_value=[DummyMetadataFetcher],
+    )
+
+    loader = DummyLoader(
+        storage=swh_storage,
+        origin_url=ORIGIN.url,
+        lister_name="other-lister",
+        lister_instance_name="",
+    )
+    loader.load()
+
+    with pytest.raises(swh.storage.exc.StorageArgumentException):
+        swh_storage.raw_extrinsic_metadata_get(ORIGIN.swhid(), METADATA_AUTHORITY)
diff --git a/swh/loader/metadata/tests/test_github.py b/swh/loader/metadata/tests/test_github.py
new file mode 100644
--- /dev/null
+++ b/swh/loader/metadata/tests/test_github.py
@@ -0,0 +1,95 @@
+# Copyright (C) 2022  The Software Heritage developers
+# See the AUTHORS file at the top-level directory of this distribution
+# License: GNU General Public License version 3, or any later version
+# See top-level LICENSE file for more information
+
+import datetime
+from pathlib import Path
+from typing import Type
+
+import pkg_resources
+
+from swh.loader.core.metadata_fetchers import MetadataFetcherProtocol
+from swh.loader.metadata import __version__
+from swh.loader.metadata.github import GitHubMetadataFetcher
+from swh.model.model import (
+    MetadataAuthority,
+    MetadataAuthorityType,
+    MetadataFetcher,
+    Origin,
+    RawExtrinsicMetadata,
+)
+
+from .test_base import DummyLoader
+
+ORIGIN = Origin("https://github.com/octocat/Hello-World")
+
+METADATA_AUTHORITY = MetadataAuthority(
+    type=MetadataAuthorityType.FORGE, url="https://github.com"
+)
+
+
+def expected_metadata(dt, datadir):
+    data_file_path = Path(datadir) / "https_api.github.com/repos_octocat_Hello-World"
+    with data_file_path.open("rb") as fd:
+        expected_metadata_bytes = fd.read()
+    return RawExtrinsicMetadata(
+        target=ORIGIN.swhid(),
+        discovery_date=dt,
+        authority=METADATA_AUTHORITY,
+        fetcher=MetadataFetcher(name="swh.loader.metadata.github", version=__version__),
+        format="application/vnd.github.v3+json",
+        metadata=expected_metadata_bytes,
+    )
+
+
+def test_type() -> None:
+    # check with mypy
+    fetcher_cls: Type[MetadataFetcherProtocol]
+    fetcher_cls = GitHubMetadataFetcher
+    print(fetcher_cls)
+
+    # check at runtime
+    fetcher = GitHubMetadataFetcher(
+        ORIGIN,
+        credentials=None,
+        lister_name="github",
+        lister_instance_name="",
+    )
+    assert isinstance(fetcher, MetadataFetcherProtocol)
+
+
+def test_github_metadata(datadir, requests_mock_datadir, mocker):
+    now = datetime.datetime.now(tz=datetime.timezone.utc)
+    mocker.patch("swh.loader.metadata.base.now", return_value=now)
+
+    fetcher = GitHubMetadataFetcher(
+        ORIGIN, credentials=None, lister_name="github", lister_instance_name=""
+    )
+
+    assert fetcher.get_origin_metadata() == [expected_metadata(now, datadir)]
+
+
+def test_github_metadata_from_loader(
+    swh_storage, mocker, datadir, requests_mock_datadir
+):
+    # Fail early if this package is not fully installed
+    assert "github" in {
+        entry_point.name
+        for entry_point in pkg_resources.iter_entry_points("swh.loader.metadata")
+    }
+
+    now = datetime.datetime.now(tz=datetime.timezone.utc)
+    mocker.patch("swh.loader.metadata.base.now", return_value=now)
+
+    loader = DummyLoader(
+        storage=swh_storage,
+        origin_url=ORIGIN.url,
+        lister_name="github",
+        lister_instance_name="",
+    )
+    loader.load()
+
+    assert swh_storage.raw_extrinsic_metadata_get(
+        ORIGIN.swhid(), METADATA_AUTHORITY
+    ).results == [expected_metadata(now, datadir)]
diff --git a/tox.ini b/tox.ini
--- a/tox.ini
+++ b/tox.ini
@@ -6,10 +6,11 @@
   testing
 deps =
   pytest-cov
+  swh.storage[testing]
 commands =
   pytest --doctest-modules \
-         {envsitepackagesdir}/swh/foo \
-         --cov={envsitepackagesdir}/swh/foo \
+         {envsitepackagesdir}/swh/loader/metadata \
+         --cov={envsitepackagesdir}/swh/loader/metadata \
          --cov-branch {posargs}
 
 [testenv:black]
@@ -31,7 +32,7 @@
 extras =
   testing
 deps =
-  mypy==0.920
+  mypy==0.942
 commands =
   mypy swh