diff --git a/craft_store/__init__.py b/craft_store/__init__.py
index cf411cd..7b777a5 100644
--- a/craft_store/__init__.py
+++ b/craft_store/__init__.py
@@ -20,9 +20,10 @@
 __version__ = "3.0.0"
 
 
-from . import creds, endpoints, errors, models
+from . import creds, endpoints, errors, models, publishergateway
 from .auth import Auth
 from .base_client import BaseClient
+from .candidauth import CandidAuth
 from .developer_token_auth import DeveloperTokenAuth
 from .http_client import HTTPClient
 from .store_client import StoreClient
@@ -33,8 +34,10 @@
     "endpoints",
     "errors",
     "models",
+    "publishergateway",
     "Auth",
     "BaseClient",
+    "CandidAuth",
     "HTTPClient",
     "StoreClient",
     "UbuntuOneStoreClient",
diff --git a/craft_store/candidauth.py b/craft_store/candidauth.py
new file mode 100644
index 0000000..76d5c3e
--- /dev/null
+++ b/craft_store/candidauth.py
@@ -0,0 +1,72 @@
+# -*- Mode:Python; indent-tabs-mode:nil; tab-width:4 -*-
+#
+# Copyright 2024 Canonical Ltd.
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public
+# License version 3 as published by the Free Software Foundation.
+#
+# 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
+# Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+"""Client for making requests towards publisher gateway."""
+
+from collections.abc import Generator
+from logging import getLogger
+from typing import Literal
+
+import httpx
+
+from craft_store import auth, creds, errors
+
+logger = getLogger(__name__)
+
+
+class CandidAuth(httpx.Auth):
+    """Request authentication using developer token."""
+
+    def __init__(
+        self,
+        *,
+        auth: auth.Auth,
+        auth_type: Literal["bearer", "macaroon"] = "bearer",
+    ) -> None:
+        self._auth = auth
+        self._auth_type = auth_type
+        self._token: str | None = None
+
+    def auth_flow(
+        self,
+        request: httpx.Request,
+    ) -> Generator[httpx.Request, httpx.Response, None]:
+        """Update request to include Authorization header."""
+        if self._token is None:
+            logger.debug("Getting candid macaroon from keyring")
+            self._token = self.get_token_from_keyring()
+
+        self._update_headers(request)
+        yield request
+
+    def get_token_from_keyring(self) -> str:
+        """Get token stored in the credentials storage."""
+        logger.debug("Getting candid from credential storage")
+        return creds.unmarshal_candid_credentials(self._auth.get_credentials())
+
+    def _update_headers(self, request: httpx.Request) -> None:
+        """Add token to the request."""
+        logger.debug("Adding ephemeral token to request headers")
+        if self._token is None:
+            raise errors.DeveloperTokenUnavailableError(
+                message="Candid token is not available"
+            )
+        request.headers["Authorization"] = self._format_auth_header()
+
+    def _format_auth_header(self) -> str:
+        if self._auth_type == "bearer":
+            return f"Bearer {self._token}"
+        return f"Macaroon {self._token}"
diff --git a/craft_store/errors.py b/craft_store/errors.py
index af763a3..7121810 100644
--- a/craft_store/errors.py
+++ b/craft_store/errors.py
@@ -15,11 +15,13 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 """Craft Store errors."""
+from __future__ import annotations
 
 import contextlib
 import logging
 from typing import Any
 
+import httpx
 import requests
 import urllib3
 import urllib3.exceptions
@@ -31,9 +33,19 @@
 class CraftStoreError(Exception):
     """Base class error for craft-store."""
 
-    def __init__(self, message: str, resolution: str | None = None) -> None:
+    def __init__(
+        self,
+        message: str,
+        details: str | None = None,
+        resolution: str | None = None,
+        store_errors: StoreErrorList | None = None,
+    ) -> None:
         super().__init__(message)
+        if not details:
+            details = str(store_errors)
+        self.details = details
         self.resolution = resolution
+        self.store_errors = store_errors
 
 
 class NetworkError(CraftStoreError):
@@ -75,7 +87,7 @@ def __repr__(self) -> str:
             if code:
                 code_list.append(code)
 
-        return "<StoreErrorList: {' '.join(code_list)}>"
+        return f"<StoreErrorList: {' '.join(code_list)}>"
 
     def __contains__(self, error_code: str) -> bool:
         return any(error.get("code") == error_code for error in self._error_list)
@@ -111,7 +123,7 @@ def _get_raw_error_list(self) -> list[dict[str, str]]:
 
         return error_list
 
-    def __init__(self, response: requests.Response) -> None:
+    def __init__(self, response: requests.Response | httpx.Response) -> None:
         self.response = response
 
         try:
@@ -126,9 +138,13 @@ def __init__(self, response: requests.Response) -> None:
             with contextlib.suppress(KeyError):
                 message = "Store operation failed:\n" + str(self.error_list)
         if message is None:
+            if isinstance(response, httpx.Response):
+                reason = response.reason_phrase
+            else:
+                reason = response.reason
             message = (
                 "Issue encountered while processing your request: "
-                f"[{response.status_code}] {response.reason}."
+                f"[{response.status_code}] {reason}."
             )
 
         super().__init__(message)
diff --git a/craft_store/publishergateway/__init__.py b/craft_store/publishergateway/__init__.py
new file mode 100644
index 0000000..f628f8a
--- /dev/null
+++ b/craft_store/publishergateway/__init__.py
@@ -0,0 +1,35 @@
+# -*- Mode:Python; indent-tabs-mode:nil; tab-width:4 -*-
+#
+# Copyright 2024 Canonical Ltd.
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public
+# License version 3 as published by the Free Software Foundation.
+#
+# 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
+# Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+"""Package containing the Publisher Gateway client and relevant metadata."""
+
+from ._request import (
+    CreateTrackRequest,
+)
+
+from ._response import (
+    PackageMetadata,
+    PublisherMetadata,
+    TrackMetadata,
+)
+from ._publishergw import PublisherGateway
+
+__all__ = [
+    "CreateTrackRequest",
+    "PackageMetadata",
+    "PublisherMetadata",
+    "TrackMetadata",
+    "PublisherGateway",
+]
diff --git a/craft_store/publishergateway/_publishergw.py b/craft_store/publishergateway/_publishergw.py
new file mode 100644
index 0000000..a2d7bea
--- /dev/null
+++ b/craft_store/publishergateway/_publishergw.py
@@ -0,0 +1,106 @@
+# -*- Mode:Python; indent-tabs-mode:nil; tab-width:4 -*-
+#
+# Copyright 2024 Canonical Ltd.
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public
+# License version 3 as published by the Free Software Foundation.
+#
+# 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
+# Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+"""Client for the publisher gateway."""
+
+from typing import cast
+import httpx
+
+from craft_store import auth, candidauth, errors
+
+from . import _request, _response
+
+
+class PublisherGateway:
+    """Client for the publisher gateway.
+
+    This class is a client wrapper for the Canonical Publisher Gateway.
+    The latest version of the server API can be seen at: https://api.charmhub.io/docs/
+
+    Each instance is only valid for one particular namespace.
+    """
+
+    def __init__(self, base_url: str, namespace: str, auth: auth.Auth) -> None:
+        self._namespace = namespace
+        self._client = httpx.Client(
+            base_url=base_url,
+            auth=candidauth.CandidAuth(auth=auth, auth_type="macaroon"),
+        )
+
+    @staticmethod
+    def _check_error(response: httpx.Response) -> None:
+        if response.is_success:
+            return
+        try:
+            error_response = response.json()
+        except Exception as exc:
+            raise errors.CraftStoreError(
+                f"Invalid response from server ({response.status_code})",
+                details=response.text,
+            ) from exc
+        error_list = error_response.get("error-list", [])
+        if response.status_code >= 500:
+            brief = f"Store had an error ({response.status_code})"
+        else:
+            brief = f"Error {response.status_code} returned from store"
+        if len(error_list) == 1:
+            brief = f"{brief}: {error_list[0].get('message')}"
+        else:
+            brief = f"{brief}. See log for details"
+        raise errors.CraftStoreError(
+            brief, store_errors=errors.StoreErrorList(error_list)
+        )
+
+    def get_package_metadata(self, name: str) -> _response.PackageMetadata:
+        """Get general metadata for a package.
+
+        :param name: The name of the package to query.
+        :returns: A dictionary matching the result from the publisher gateway.
+
+        API docs: https://api.charmhub.io/docs/default.html#package_metadata
+        """
+        response = self._client.get(
+            url=f"/v1/{self._namespace}/{name}",
+        )
+        self._check_error(response)
+        return cast(_response.PackageMetadata, response.json()["metadata"])
+
+    def create_tracks(self, name: str, *tracks: _request.CreateTrackRequest) -> int:
+        """Create one or more tracks in the store.
+
+        :param name: The store name (i.e. the specific charm, snap or other package)
+            to which this track will be attached.
+        :param tracks: Each track is a dictionary mapping query values.
+        :returns: The number of tracks created by the store.
+        :raises: ValueError if a track name is invalid.
+
+        API docs: https://api.charmhub.io/docs/default.html#create_tracks
+        """
+        bad_track_names = {
+            track["name"]
+            for track in tracks
+            if not _request.TRACK_NAME_REGEX.match(track["name"])
+            or len(track["name"]) > 28
+        }
+        if bad_track_names:
+            bad_tracks = ", ".join(sorted(bad_track_names))
+            raise ValueError(f"The following track names are invalid: {bad_tracks}")
+
+        response = self._client.post(
+            f"/v1/{self._namespace}/{name}/tracks", json=tracks
+        )
+        self._check_error(response)
+
+        return int(response.json()["num-tracks-created"])
diff --git a/craft_store/publishergateway/_request.py b/craft_store/publishergateway/_request.py
new file mode 100644
index 0000000..fd01bb5
--- /dev/null
+++ b/craft_store/publishergateway/_request.py
@@ -0,0 +1,41 @@
+# -*- Mode:Python; indent-tabs-mode:nil; tab-width:4 -*-
+#
+# Copyright 2024 Canonical Ltd.
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public
+# License version 3 as published by the Free Software Foundation.
+#
+# 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
+# Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+"""Request models for the publisher gateway."""
+
+import re
+from typing import Annotated, TypedDict
+
+import annotated_types
+from typing_extensions import NotRequired
+
+TRACK_NAME_REGEX = re.compile(r"^[a-zA-Z0-9](?:[_.-]?[a-zA-Z0-9])*$")
+"""A regular expression guarding track names.
+
+Retrieved from https://api.staging.charmhub.io/docs/default.html#create_tracks
+"""
+
+CreateTrackRequest = TypedDict(
+    "CreateTrackRequest",
+    {
+        "name": Annotated[
+            str,
+            annotated_types.Len(1, 28),
+            annotated_types.Predicate(lambda name: bool(TRACK_NAME_REGEX.match(name))),
+        ],
+        "version-pattern": NotRequired[str | None],
+        "automatic-phasing-percentage": NotRequired[str | None],
+    },
+)
diff --git a/craft_store/publishergateway/_response.py b/craft_store/publishergateway/_response.py
new file mode 100644
index 0000000..5f0c6e2
--- /dev/null
+++ b/craft_store/publishergateway/_response.py
@@ -0,0 +1,71 @@
+# -*- Mode:Python; indent-tabs-mode:nil; tab-width:4 -*-
+#
+# Copyright 2024 Canonical Ltd.
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public
+# License version 3 as published by the Free Software Foundation.
+#
+# 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
+# Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+"""Response models for the publisher gateway."""
+
+from typing import TypedDict
+
+from typing_extensions import NotRequired
+
+PublisherMetadata = TypedDict(
+    "PublisherMetadata",
+    {
+        "display-name": str | None,
+        "email": NotRequired[str],
+        "id": str,
+        "username": str | None,
+        "validation": NotRequired[str],
+    },
+)
+
+TrackMetadata = TypedDict(
+    "TrackMetadata",
+    {
+        "name": str,
+        "version-pattern": str | None,
+        "automatic-phasing-percentage": float | None,
+        "created-at": str,
+    },
+)
+
+
+PackageMetadata = TypedDict(
+    "PackageMetadata",
+    {
+        "authority": NotRequired[str | None],
+        "contact": NotRequired[str | None],
+        "default-track": NotRequired[str | None],
+        "description": NotRequired[str | None],
+        "id": str,
+        "links": NotRequired[list[str] | None],
+        "media": list[dict[str, str]],
+        "name": NotRequired[str | None],
+        "private": bool,
+        "publisher": PublisherMetadata,
+        "status": str,
+        "store": str,
+        "summary": NotRequired[str | None],
+        "title": NotRequired[str | None],
+        "track-guardrails": NotRequired[
+            dict[
+                str,
+                str,
+            ]
+        ],
+        "tracks": list[TrackMetadata] | None,
+        "type": str,
+        "website": NotRequired[str | None],
+    },
+)
diff --git a/pyproject.toml b/pyproject.toml
index 814ed38..dcea9ac 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -6,6 +6,7 @@ authors = [
     {name = "Canonical Ltd.", email = "snapcraft@lists.snapcraft.io"},
 ]
 dependencies = [
+    "annotated-types>=0.6.0",
     "keyring>=23.0",
     "overrides>=7.0.0",
     "requests>=2.27.0",
@@ -142,7 +143,8 @@ minversion = "7.0"
 testpaths = "tests"
 xfail_strict = true
 markers = [
-    "disable_fake_keyring"
+    "disable_fake_keyring",
+    "slow: tests that take a long time",
 ]
 
 [tool.coverage.run]
diff --git a/tests/integration/conftest.py b/tests/integration/conftest.py
index 4999c9f..98c1118 100644
--- a/tests/integration/conftest.py
+++ b/tests/integration/conftest.py
@@ -21,15 +21,20 @@
 
 import pytest
 import yaml
-from craft_store import StoreClient, endpoints
+from craft_store import StoreClient, auth, endpoints, publishergateway
+
+
+@pytest.fixture(scope="session")
+def charmhub_base_url() -> str:
+    return os.getenv("CRAFT_STORE_CHARMHUB", "https://api.staging.charmhub.io")
 
 
 @pytest.fixture
-def charm_client():
+def charm_client(charmhub_base_url):
     """A common StoreClient for charms"""
     return StoreClient(
         application_name="integration-test",
-        base_url="https://api.staging.charmhub.io",
+        base_url=charmhub_base_url,
         storage_base_url="https://storage.staging.snapcraftcontent.com",
         endpoints=endpoints.CHARMHUB,
         user_agent="integration-tests",
@@ -47,6 +52,22 @@ def charmhub_charm_name():
     return os.getenv("CRAFT_STORE_TEST_CHARM", default="craft-store-test")
 
 
+@pytest.fixture
+def charmhub_auth(charmhub_base_url):
+    return auth.Auth(
+        application_name="craft-store-integration-tests",
+        host=charmhub_base_url,
+        environment_auth="CRAFT_STORE_CHARMCRAFT_CREDENTIALS",
+    )
+
+
+@pytest.fixture
+def publisher_gateway(charmhub_base_url, charmhub_auth):
+    return publishergateway.PublisherGateway(
+        base_url=charmhub_base_url, namespace="charm", auth=charmhub_auth
+    )
+
+
 @pytest.fixture
 def fake_charm_file(tmp_path, charmhub_charm_name):
     """Provide a fake charm to upload to charmhub."""
diff --git a/tests/integration/publishergateway/__init__.py b/tests/integration/publishergateway/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/tests/integration/publishergateway/test_read.py b/tests/integration/publishergateway/test_read.py
new file mode 100644
index 0000000..1df570d
--- /dev/null
+++ b/tests/integration/publishergateway/test_read.py
@@ -0,0 +1,34 @@
+# -*- Mode:Python; indent-tabs-mode:nil; tab-width:4 -*-
+#
+# Copyright 2024 Canonical Ltd.
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public
+# License version 3 as published by the Free Software Foundation.
+#
+# 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
+# Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+"""Tests that only involve reading from the store."""
+
+
+from craft_store import publishergateway
+
+from tests.integration.conftest import needs_charmhub_credentials
+
+
+@needs_charmhub_credentials()
+def test_get_package_metadata(
+    publisher_gateway: publishergateway.PublisherGateway, charmhub_charm_name: str
+):
+    metadata = publisher_gateway.get_package_metadata(charmhub_charm_name)
+    assert metadata.get("name") == charmhub_charm_name
+    assert metadata.get("default-track")
+    assert len(metadata["id"]) == len("sCPqM62aJhbLUJmpPfFbsxbd2zpR6dcu")
+    assert metadata.get("default-track") in {
+        track["name"] for track in metadata.get("tracks") or []
+    }
diff --git a/tests/integration/publishergateway/test_write.py b/tests/integration/publishergateway/test_write.py
new file mode 100644
index 0000000..ed3ae81
--- /dev/null
+++ b/tests/integration/publishergateway/test_write.py
@@ -0,0 +1,95 @@
+# -*- Mode:Python; indent-tabs-mode:nil; tab-width:4 -*-
+#
+# Copyright 2024 Canonical Ltd.
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public
+# License version 3 as published by the Free Software Foundation.
+#
+# 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
+# Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+"""Single-endpoint write tests (likely with a read query after)."""
+
+
+import contextlib
+import time
+
+import pytest
+from craft_store import errors, publishergateway
+
+from tests.integration.conftest import needs_charmhub_credentials
+
+
+@pytest.mark.slow
+@needs_charmhub_credentials()
+@pytest.mark.parametrize("version_pattern", [None, r"\d+"])
+@pytest.mark.parametrize("percentages", [None, 50])
+def test_create_tracks(
+    publisher_gateway: publishergateway.PublisherGateway,
+    charmhub_charm_name: str,
+    version_pattern,
+    percentages,
+):
+    track_name = str(time.time_ns())
+
+    tracks_created = publisher_gateway.create_tracks(
+        charmhub_charm_name,
+        {
+            "name": track_name,
+            "version-pattern": version_pattern,
+            "automatic-phasing-percentage": percentages,
+        },
+    )
+    assert tracks_created == 1
+
+    metadata = publisher_gateway.get_package_metadata(charmhub_charm_name)
+    if "tracks" not in metadata or not metadata["tracks"]:
+        raise ValueError("No tracks returned from the store")
+
+    for track in metadata["tracks"]:
+        if track["name"] != track_name:
+            continue
+        assert track["version-pattern"] == version_pattern
+        assert track["automatic-phasing-percentage"] == percentages
+        break
+    else:
+        raise ValueError(f"Track {track_name} created but not returned from the store.")
+
+
+@pytest.mark.slow
+@needs_charmhub_credentials()
+def test_create_disallowed_track(
+    publisher_gateway: publishergateway.PublisherGateway, charmhub_charm_name: str
+):
+    track_name = "disallowed"
+
+    with pytest.raises(errors.CraftStoreError, match="Invalid track name") as exc_info:
+        publisher_gateway.create_tracks(charmhub_charm_name, {"name": track_name})
+
+    assert exc_info.value.store_errors is not None
+    assert "invalid-tracks" in exc_info.value.store_errors
+
+
+@pytest.mark.slow
+@needs_charmhub_credentials()
+def test_create_existing_track(
+    publisher_gateway: publishergateway.PublisherGateway, charmhub_charm_name: str
+):
+    track_name = "1"
+
+    # Suppress the error because we don't care about the first time
+    with contextlib.suppress(errors.CraftStoreError):
+        publisher_gateway.create_tracks(charmhub_charm_name, {"name": track_name})
+
+    with pytest.raises(
+        errors.CraftStoreError, match="Conflicting track exists"
+    ) as exc_info:
+        publisher_gateway.create_tracks(charmhub_charm_name, {"name": track_name})
+
+    assert exc_info.value.store_errors is not None
+    assert "conflicting-tracks" in exc_info.value.store_errors
diff --git a/tests/unit/conftest.py b/tests/unit/conftest.py
index 6f72900..5cba9fb 100644
--- a/tests/unit/conftest.py
+++ b/tests/unit/conftest.py
@@ -16,8 +16,10 @@
 
 import datetime
 from typing import Any
+from unittest import mock
 from unittest.mock import patch
 
+import craft_store
 import pytest
 
 
@@ -108,3 +110,8 @@ def new_auth(request) -> bool:
     :see: base_client.wrap_credentials()
     """
     return request.param
+
+
+@pytest.fixture
+def mock_auth():
+    return mock.Mock(spec=craft_store.Auth)
diff --git a/tests/unit/test_candid_auth.py b/tests/unit/test_candid_auth.py
new file mode 100644
index 0000000..e499479
--- /dev/null
+++ b/tests/unit/test_candid_auth.py
@@ -0,0 +1,45 @@
+#  -*- Mode:Python; indent-tabs-mode:nil; tab-width:4 -*
+#
+#  Copyright 2024 Canonical Ltd.
+#
+#  This program is free software; you can redistribute it and/or
+#  modify it under the terms of the GNU Lesser General Public
+#  License version 3 as published by the Free Software Foundation.
+#
+#  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
+#  Lesser General Public License for more details.
+#
+#  You should have received a copy of the GNU Lesser General Public License
+#  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+"""Tests for authorizing requests using CandidAuth."""
+
+
+import httpx
+import pytest
+from craft_store import CandidAuth
+
+
+@pytest.fixture
+def candid_auth(mock_auth):
+    return CandidAuth(
+        auth=mock_auth,
+    )
+
+
+def test_get_token_from_keyring(mock_auth, candid_auth):
+    mock_auth.get_credentials.return_value = "{}"
+
+    assert candid_auth.get_token_from_keyring() == "{}"
+
+
+def test_auth_flow(mock_auth, candid_auth):
+    mock_auth.get_credentials.return_value = "{}"
+
+    request = httpx.Request("GET", "http://localhost")
+
+    next(candid_auth.auth_flow(request))
+
+    assert request.headers["Authorization"] == "Bearer {}"
diff --git a/tests/unit/test_publishergateway.py b/tests/unit/test_publishergateway.py
new file mode 100644
index 0000000..261e8d5
--- /dev/null
+++ b/tests/unit/test_publishergateway.py
@@ -0,0 +1,128 @@
+# -*- Mode:Python; indent-tabs-mode:nil; tab-width:4 -*-
+#
+# Copyright 2024 Canonical Ltd.
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public
+# License version 3 as published by the Free Software Foundation.
+#
+# 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
+# Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+"""Unit tests for the publisher gateway."""
+
+from unittest import mock
+
+import httpx
+import pytest
+from craft_store import errors, publishergateway
+
+
+@pytest.fixture
+def mock_httpx_client():
+    return mock.Mock(spec=httpx.Client)
+
+
+@pytest.fixture
+def publisher_gateway(mock_httpx_client):
+    gw = publishergateway.PublisherGateway("http://localhost", "charm", mock.Mock())
+    gw._client = mock_httpx_client
+    return gw
+
+
+@pytest.mark.parametrize("response", [httpx.Response(status_code=204)])
+def test_check_error_on_success(response: httpx.Response):
+    assert publishergateway.PublisherGateway._check_error(response) is None
+
+
+@pytest.mark.parametrize(
+    ("response", "match"),
+    [
+        pytest.param(
+            httpx.Response(503, text="help!"),
+            r"Invalid response from server \(503\)",
+            id="really-bad",
+        ),
+        pytest.param(
+            httpx.Response(
+                503,
+                json={"error-list": [{"code": "whelp", "message": "we done goofed"}]},
+            ),
+            r"Store had an error \(503\): we done goofed",
+            id="server-error",
+        ),
+        pytest.param(
+            httpx.Response(
+                400,
+                json={"error-list": [{"code": "whelp", "message": "you messed up"}]},
+            ),
+            r"Error 400 returned from store: you messed up",
+            id="client-error",
+        ),
+        pytest.param(
+            httpx.Response(
+                418,
+                json={
+                    "error-list": [
+                        {"code": "whelp", "message": "I am a teapot"},
+                        {
+                            "code": "bad",
+                            "message": "Why would you ask me for a coffee?",
+                        },
+                    ]
+                },
+            ),
+            r"Error 418 returned from store. See log for details",
+            id="multiple-client-errors",
+        ),
+    ],
+)
+def test_check_error(response: httpx.Response, match):
+    with pytest.raises(errors.CraftStoreError, match=match):
+        publishergateway.PublisherGateway._check_error(response)
+
+
+def test_get_package_metadata(
+    mock_httpx_client: mock.Mock, publisher_gateway: publishergateway.PublisherGateway
+):
+    mock_httpx_client.get.return_value = httpx.Response(
+        200, json={"metadata": {"meta": "data"}}
+    )
+
+    assert publisher_gateway.get_package_metadata("my-package") == {"meta": "data"}
+
+    mock_httpx_client.get.assert_called_once_with(url="/v1/charm/my-package")
+
+
+@pytest.mark.parametrize(
+    ("tracks", "match"),
+    [
+        ([{"name": "-"}], ": -$"),
+        (
+            [{"name": "123456789012345678901234567890"}],
+            ": 123456789012345678901234567890$",
+        ),
+        ([{"name": "-"}, {"name": "_!"}], ": -, _!$"),
+    ],
+)
+def test_create_tracks_validation(
+    publisher_gateway: publishergateway.PublisherGateway,
+    tracks,
+    match,
+):
+    with pytest.raises(ValueError, match=match):
+        publisher_gateway.create_tracks("my-name", *tracks)
+
+
+def test_create_tracks_success(
+    mock_httpx_client: mock.Mock, publisher_gateway: publishergateway.PublisherGateway
+):
+    mock_httpx_client.post.return_value = httpx.Response(
+        200, json={"num-tracks-created": 0}
+    )
+
+    assert publisher_gateway.create_tracks("my-name") == 0