diff --git a/docs/apidoc/api_client.rst b/docs/apidoc/api_client.rst
new file mode 100644
index 0000000..52cf334
--- /dev/null
+++ b/docs/apidoc/api_client.rst
@@ -0,0 +1,25 @@
+.. _api_client:
+
+==========
+API client
+==========
+
+.. autoclass:: qiskit_aqt_provider.api_client.portal_client.PortalClient
+   :members:
+   :show-inheritance:
+   :inherited-members:
+
+.. autoclass:: qiskit_aqt_provider.api_client.models.Workspaces
+   :members:
+   :show-inheritance:
+   :exclude-members: __init__, __new__, model_fields, model_computed_fields, model_config
+
+.. autoclass:: qiskit_aqt_provider.api_client.models.Workspace
+   :members:
+   :show-inheritance:
+   :exclude-members: __init__, __new__, model_fields, model_computed_fields, model_config
+
+.. autoclass:: qiskit_aqt_provider.api_client.models.Resource
+   :members:
+   :show-inheritance:
+   :exclude-members: __init__, __new__, model_fields, model_computed_fields, model_config
diff --git a/docs/conf.py b/docs/conf.py
index dc53c90..7967748 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -57,6 +57,10 @@
     ("py:class", "Target"),
     ("py:exc", "QiskitBackendNotFoundError"),
     ("py:class", "qiskit_aqt_provider.aqt_resource._OptionsType"),
+    # No inventory available for httpx
+    # https://github.com/encode/httpx/issues/3145
+    ("py:exc", "httpx.NetworkError"),
+    ("py:exc", "httpx.HTTPStatusError"),
 ]
 nitpick_ignore_regex = [
     ("py:class", r"qiskit_aqt_provider\.api_models_generated.*"),
@@ -83,4 +87,5 @@
 intersphinx_mapping = {
     "python": ("https://docs.python.org/3", None),
     "qiskit": ("https://docs.quantum.ibm.com/api/qiskit/", None),
+    "pydantic": ("https://docs.pydantic.dev/latest/", None),
 }
diff --git a/docs/index.rst b/docs/index.rst
index 08aaba8..86fb9c0 100644
--- a/docs/index.rst
+++ b/docs/index.rst
@@ -72,6 +72,7 @@ For more details see the :ref:`user guide <user-guide>`, a selection of `example
   Options <apidoc/options>
   Qiskit primitives <apidoc/primitives>
   Transpiler plugin <apidoc/transpiler_plugin>
+  API client <apidoc/api_client>
 
 .. toctree::
   :hidden:
diff --git a/qiskit_aqt_provider/api_client/__init__.py b/qiskit_aqt_provider/api_client/__init__.py
index c7f61e9..c13ccf7 100644
--- a/qiskit_aqt_provider/api_client/__init__.py
+++ b/qiskit_aqt_provider/api_client/__init__.py
@@ -7,3 +7,17 @@
 # Any modifications or derivative works of this code must retain this
 # copyright notice, and modified files need to carry a notice indicating
 # that they have been altered from the originals.
+
+from .models import Resource, ResourceType, Workspace, Workspaces
+from .portal_client import DEFAULT_PORTAL_URL, PortalClient
+from .versions import __version__
+
+__all__ = [
+    "DEFAULT_PORTAL_URL",
+    "PortalClient",
+    "Resource",
+    "ResourceType",
+    "Workspace",
+    "Workspaces",
+    "__version__",
+]
diff --git a/qiskit_aqt_provider/api_client/models.py b/qiskit_aqt_provider/api_client/models.py
index 1267da9..952d168 100644
--- a/qiskit_aqt_provider/api_client/models.py
+++ b/qiskit_aqt_provider/api_client/models.py
@@ -15,6 +15,8 @@
 import importlib.metadata
 import platform
 import re
+import typing
+from collections.abc import Collection, Iterator
 from re import Pattern
 from typing import Any, Final, Literal, Optional, Union
 from uuid import UUID
@@ -22,7 +24,7 @@
 import httpx
 import pydantic as pdt
 from qiskit.providers.exceptions import JobError
-from typing_extensions import Self, TypeAlias
+from typing_extensions import Self, TypeAlias, override
 
 from . import models_generated as api_models
 from .models_generated import (
@@ -32,7 +34,6 @@
     QuantumCircuits,
     SubmitJobRequest,
 )
-from .models_generated import Type as ResourceType
 
 __all__ = [
     "Circuit",
@@ -43,7 +44,6 @@
     "QuantumCircuit",
     "QuantumCircuits",
     "Response",
-    "ResourceType",
 ]
 
 
@@ -78,11 +78,153 @@ def http_client(
     return httpx.Client(headers=headers, base_url=base_url, timeout=10.0, follow_redirects=True)
 
 
-class Workspaces(pdt.RootModel[list[api_models.Workspace]]):
-    """List of available workspaces and devices."""
+ResourceType: TypeAlias = Literal["device", "simulator", "offline_simulator"]
+
+
+class Resource(pdt.BaseModel):
+    """Description of a resource.
+
+    This is the element type in :py:attr:`Workspace.resources`.
+    """
+
+    model_config = pdt.ConfigDict(frozen=True)
+
+    workspace_id: str
+    """Identifier of the workspace this resource belongs to."""
+
+    resource_id: str
+    """Resource identifier."""
+
+    resource_name: str
+    """Resource name."""
+
+    resource_type: ResourceType
+    """Type of resource."""
+
+
+class Workspace(pdt.BaseModel):
+    """Description of a workspace and the resources it contains.
+
+    This is the element type in the :py:class:`Workspaces` container.
+    """
+
+    model_config = pdt.ConfigDict(frozen=True)
+
+    workspace_id: str
+    """Workspace identifier."""
+
+    resources: list[Resource]
+    """Resources in the workspace."""
+
+
+class Workspaces(
+    pdt.RootModel,  # type: ignore[type-arg]
+    Collection[Workspace],
+):
+    """List of available workspaces and devices.
+
+    ..
+        >>> workspaces = Workspaces(
+        ...     root=[
+        ...         api_models.Workspace(
+        ...             id="workspace0",
+        ...             resources=[
+        ...                 api_models.Resource(
+        ...                     id="resource0",
+        ...                     name="resource0",
+        ...                     type=api_models.Type.device,
+        ...                 ),
+        ...             ],
+        ...         ),
+        ...        api_models.Workspace(
+        ...            id="workspace1",
+        ...            resources=[
+        ...                api_models.Resource(
+        ...                    id="resource0",
+        ...                    name="resource0",
+        ...                    type=api_models.Type.device,
+        ...                ),
+        ...                api_models.Resource(
+        ...                    id="resource1",
+        ...                    name="resource1",
+        ...                    type=api_models.Type.simulator,
+        ...                ),
+        ...            ],
+        ...        ),
+        ...    ]
+        ... )
+
+    Examples:
+        Assume a :py:class:`Workspaces` instance retrieved from the API with
+        the following contents:
+
+        .. code-block::
+
+            | Workspace ID | Resource ID | Resource Type |
+            |--------------+-------------+---------------|
+            | workspace0   | resource0   | device        |
+            | workspace1   | resource0   | device        |
+            | workspace1   | resource1   | simulator     |
+
+        Gather basic information:
+
+        >>> # workspaces = PortalClient(...).workspaces()
+        >>> len(workspaces)
+        2
+        >>> [ws.workspace_id for ws in workspaces]
+        ['workspace0', 'workspace1']
+
+        Inclusion tests rely only on the identifier:
+
+        >>> Workspace(workspace_id="workspace0", resources=[]) in workspaces
+        True
+
+        The :py:meth:`Workspaces.filter` method allows for complex filtering. For example
+        by workspace identifier ending in ``0``:
+
+        >>> [ws.workspace_id for ws in workspaces.filter(workspace_pattern=re.compile(".+0$"))]
+        ['workspace0']
+
+        or only the non-simulated devices:
+
+        >>> workspaces_devices = workspaces.filter(backend_type="device")
+        >>> [(ws.workspace_id, resource.resource_id)
+        ...  for ws in workspaces_devices for resource in ws.resources]
+        [('workspace0', 'resource0'), ('workspace1', 'resource0')]
+    """
 
     root: list[api_models.Workspace]
 
+    @override
+    def __len__(self) -> int:
+        """Number of available workspaces."""
+        return len(self.root)
+
+    @override
+    def __iter__(self) -> Iterator[Workspace]:  # type: ignore[override]
+        """Iterator over the workspaces."""
+        for ws in self.root:
+            yield Workspace(
+                workspace_id=ws.id,
+                resources=[
+                    Resource(
+                        workspace_id=ws.id,
+                        resource_id=res.id,
+                        resource_name=res.name,
+                        resource_type=typing.cast(ResourceType, res.type.value),
+                    )
+                    for res in ws.resources
+                ],
+            )
+
+    @override
+    def __contains__(self, obj: object) -> bool:
+        """Whether a given workspace is in this workspaces collection."""
+        if not isinstance(obj, Workspace):  # pragma: no cover
+            return False
+
+        return any(ws.id == obj.workspace_id for ws in self.root)
+
     def filter(
         self,
         *,
@@ -100,7 +242,7 @@ def filter(
             backend_type: backend type to select.
 
         Returns:
-            Workspaces model that only contains matching resources.
+            :py:class:`Workspaces` instance that only contains matching resources.
         """
         filtered_workspaces = []
         for workspace in self.root:
@@ -110,7 +252,7 @@ def filter(
             filtered_resources = []
 
             for resource in workspace.resources:
-                if backend_type is not None and resource.type is not backend_type:
+                if backend_type is not None and resource.type.value != backend_type:
                     continue
 
                 if name_pattern is not None and not re.match(name_pattern, resource.id):
@@ -125,27 +267,6 @@ def filter(
         return self.__class__(root=filtered_workspaces)
 
 
-GeneralResourceType: TypeAlias = Literal["device", "simulator", "offline_simulator"]
-
-
-class ResourceId(pdt.BaseModel):
-    """Resource identification and metadata."""
-
-    model_config = pdt.ConfigDict(frozen=True)
-
-    workspace_id: str
-    """Workspace containing the resource."""
-
-    resource_id: str
-    """Unique identifier of the resource in the containing workspace."""
-
-    resource_name: str
-    """Pretty display name for the resource."""
-
-    resource_type: GeneralResourceType
-    """Resource type, also includes offline simulators."""
-
-
 class Operation:
     """Factories for API payloads of circuit operations."""
 
diff --git a/qiskit_aqt_provider/api_client/portal_client.py b/qiskit_aqt_provider/api_client/portal_client.py
new file mode 100644
index 0000000..0feabfd
--- /dev/null
+++ b/qiskit_aqt_provider/api_client/portal_client.py
@@ -0,0 +1,67 @@
+# (C) Copyright Alpine Quantum Technologies GmbH 2024
+#
+# This code is licensed under the Apache License, Version 2.0. You may
+# obtain a copy of this license in the LICENSE.txt file in the root directory
+# of this source tree or at http://www.apache.org/licenses/LICENSE-2.0.
+#
+# Any modifications or derivative works of this code must retain this
+# copyright notice, and modified files need to carry a notice indicating
+# that they have been altered from the originals.
+
+import os
+from typing import Final, Optional
+
+import httpx
+
+from . import models
+from .versions import make_user_agent
+
+DEFAULT_PORTAL_URL: Final = httpx.URL("https://arnica.aqt.eu")
+"""Default URL for the remote portal."""
+
+
+class PortalClient:
+    """Client for the AQT portal API."""
+
+    USER_AGENT_NAME: Final = "aqt-portal-client"
+
+    def __init__(
+        self, *, token: str, user_agent_extra: Optional[str] = None, timeout: Optional[float] = 10.0
+    ) -> None:
+        """Initialize a new client for the AQT remote computing portal API.
+
+        The portal base URL can be overridden using the ``AQT_PORTAL_URL``
+        environment variable.
+
+        Args:
+            token: authentication token.
+            user_agent_extra: data appended to the default user-agent string.
+            timeout: HTTP timeout, in seconds.
+        """
+        self.portal_url = httpx.URL(os.environ.get("AQT_PORTAL_URL", DEFAULT_PORTAL_URL))
+
+        user_agent = make_user_agent(self.USER_AGENT_NAME, extra=user_agent_extra)
+        headers = {"User-Agent": user_agent}
+
+        if token:
+            headers["Authorization"] = f"Bearer {token}"
+
+        self._http_client = httpx.Client(
+            base_url=self.portal_url.join("/api/v1"),
+            headers=headers,
+            timeout=timeout,
+            follow_redirects=True,
+        )
+
+    def workspaces(self) -> models.Workspaces:
+        """List the workspaces visible to the used token.
+
+        Raises:
+            httpx.NetworkError: connection to the remote portal failed.
+            httpx.HTTPStatusError: something went wrong with the request to the remote portal.
+        """
+        with self._http_client as client:
+            response = client.get("/workspaces")
+
+        response.raise_for_status()
+        return models.Workspaces.model_validate(response.json())
diff --git a/qiskit_aqt_provider/api_client/versions.py b/qiskit_aqt_provider/api_client/versions.py
new file mode 100644
index 0000000..ad4671c
--- /dev/null
+++ b/qiskit_aqt_provider/api_client/versions.py
@@ -0,0 +1,37 @@
+# (C) Copyright Alpine Quantum Technologies GmbH 2024
+#
+# This code is licensed under the Apache License, Version 2.0. You may
+# obtain a copy of this license in the LICENSE.txt file in the root directory
+# of this source tree or at http://www.apache.org/licenses/LICENSE-2.0.
+#
+# Any modifications or derivative works of this code must retain this
+# copyright notice, and modified files need to carry a notice indicating
+# that they have been altered from the originals.
+
+import importlib.metadata
+import platform
+from typing import Final, Optional
+
+PACKAGE_VERSION: Final = importlib.metadata.version("qiskit-aqt-provider")
+__version__: Final = PACKAGE_VERSION
+
+
+def make_user_agent(name: str, *, extra: Optional[str] = None) -> str:
+    """User-agent strings factory.
+
+    Args:
+        name: main name of the component to build a user-agent string for.
+        extra: arbitrary extra data, appended to the default string.
+    """
+    user_agent = " ".join(
+        [
+            f"{name}/{PACKAGE_VERSION}",
+            f"({platform.system()};",
+            f"{platform.python_implementation()}/{platform.python_version()})",
+        ]
+    )
+
+    if extra:
+        user_agent += f" {extra}"
+
+    return user_agent
diff --git a/qiskit_aqt_provider/aqt_provider.py b/qiskit_aqt_provider/aqt_provider.py
index f2b127e..874d37b 100644
--- a/qiskit_aqt_provider/aqt_provider.py
+++ b/qiskit_aqt_provider/aqt_provider.py
@@ -16,14 +16,13 @@
 import re
 import warnings
 from collections import defaultdict
-from collections.abc import Sequence
+from collections.abc import Iterable, Sequence
 from dataclasses import dataclass
 from operator import attrgetter
 from pathlib import Path
 from re import Pattern
 from typing import (
     Final,
-    Literal,
     Optional,
     Union,
     overload,
@@ -35,7 +34,7 @@
 from tabulate import tabulate
 from typing_extensions import TypeAlias, override
 
-from qiskit_aqt_provider.api_client import models as api_models
+from qiskit_aqt_provider.api_client import PortalClient, Resource, ResourceType, Workspace
 from qiskit_aqt_provider.aqt_resource import (
     AQTDirectAccessResource,
     AQTResource,
@@ -146,9 +145,6 @@ def table(self) -> list[list[str]]:
 class AQTProvider:
     """Provider for backends from Alpine Quantum Technologies (AQT)."""
 
-    # Set AQT_PORTAL_URL environment variable to override
-    DEFAULT_PORTAL_URL: Final = "https://arnica.aqt.eu"
-
     def __init__(
         self,
         access_token: Optional[str] = None,
@@ -183,9 +179,6 @@ def __init__(
         if load_dotenv or dotenv_path is not None:
             dotenv.load_dotenv(dotenv_path)
 
-        portal_base_url = os.environ.get("AQT_PORTAL_URL", AQTProvider.DEFAULT_PORTAL_URL)
-        self.portal_url = f"{portal_base_url}/api/v1"
-
         if access_token is None:
             self.access_token = os.environ.get("AQT_TOKEN", "")
         else:
@@ -200,17 +193,18 @@ def __init__(
         self.name = "aqt_provider"
 
     @property
-    def _http_client(self) -> httpx.Client:
-        """HTTP client for communicating with the AQT cloud service."""
-        return api_models.http_client(
-            base_url=self.portal_url, token=self.access_token, user_agent_extra=USER_AGENT_EXTRA
+    def _portal_client(self) -> PortalClient:
+        """API client."""
+        return PortalClient(
+            token=self.access_token,
+            user_agent_extra=USER_AGENT_EXTRA,
         )
 
     def backends(
         self,
         name: Optional[Union[str, Pattern[str]]] = None,
         *,
-        backend_type: Optional[Literal["device", "simulator", "offline_simulator"]] = None,
+        backend_type: Optional[ResourceType] = None,
         workspace: Optional[Union[str, Pattern[str]]] = None,
     ) -> BackendsTable:
         """Search for cloud backends matching given criteria.
@@ -236,17 +230,14 @@ def backends(
         if isinstance(workspace, str):
             workspace = re.compile(f"^{workspace}$")
 
-        remote_workspaces = api_models.Workspaces(root=[])
+        remote_workspaces: Iterable[Workspace] = []
 
+        # Only query if remote resources are requested.
         if backend_type != "offline_simulator":
             with contextlib.suppress(httpx.HTTPError, httpx.NetworkError):
-                with self._http_client as client:
-                    resp = client.get("/workspaces")
-                    resp.raise_for_status()
-
-                remote_workspaces = api_models.Workspaces.model_validate(resp.json()).filter(
+                remote_workspaces = self._portal_client.workspaces().filter(
                     name_pattern=name,
-                    backend_type=api_models.ResourceType(backend_type) if backend_type else None,
+                    backend_type=backend_type if backend_type else None,
                     workspace_pattern=workspace,
                 )
 
@@ -262,7 +253,7 @@ def backends(
                 backends.append(
                     OfflineSimulatorResource(
                         self,
-                        resource_id=api_models.ResourceId(
+                        resource_id=Resource(
                             workspace_id="default",
                             resource_id=simulator.id,
                             resource_name=simulator.name,
@@ -278,14 +269,9 @@ def backends(
             + [
                 AQTResource(
                     self,
-                    resource_id=api_models.ResourceId(
-                        workspace_id=_workspace.id,
-                        resource_id=resource.id,
-                        resource_name=resource.name,
-                        resource_type=resource.type.value,
-                    ),
+                    resource_id=resource,
                 )
-                for _workspace in remote_workspaces.root
+                for _workspace in remote_workspaces
                 for resource in _workspace.resources
             ]
         )
@@ -294,7 +280,7 @@ def get_backend(
         self,
         name: Optional[Union[str, Pattern[str]]] = None,
         *,
-        backend_type: Optional[Literal["device", "simulator", "offline_simulator"]] = None,
+        backend_type: Optional[ResourceType] = None,
         workspace: Optional[Union[str, Pattern[str]]] = None,
     ) -> AQTResource:
         """Return a handle for a cloud quantum computing resource matching the specified filtering.
diff --git a/qiskit_aqt_provider/aqt_resource.py b/qiskit_aqt_provider/aqt_resource.py
index cd2bfad..023332c 100644
--- a/qiskit_aqt_provider/aqt_resource.py
+++ b/qiskit_aqt_provider/aqt_resource.py
@@ -35,6 +35,7 @@
 from qiskit_aer import AerJob, AerSimulator, noise
 from typing_extensions import override
 
+from qiskit_aqt_provider import api_client
 from qiskit_aqt_provider.api_client import models as api_models
 from qiskit_aqt_provider.api_client import models_direct as api_models_direct
 from qiskit_aqt_provider.aqt_job import AQTDirectAccessJob, AQTJob
@@ -107,7 +108,7 @@ def __init__(
             {
                 "backend_name": name,
                 "backend_version": 2,
-                "url": provider.portal_url,
+                "url": str(provider._portal_client.portal_url),
                 "simulator": True,
                 "local": False,
                 "coupling_map": None,
@@ -209,7 +210,7 @@ class AQTResource(_ResourceBase[AQTOptions]):
     def __init__(
         self,
         provider: "AQTProvider",
-        resource_id: api_models.ResourceId,
+        resource_id: api_client.Resource,
     ) -> None:
         """Initialize the backend.
 
@@ -223,7 +224,7 @@ def __init__(
             options_type=AQTOptions,
         )
 
-        self._http_client: httpx.Client = provider._http_client
+        self._http_client: httpx.Client = provider._portal_client._http_client
         self.resource_id = resource_id
 
     def run(self, circuits: Union[QuantumCircuit, list[QuantumCircuit]], **options: Any) -> AQTJob:
@@ -434,7 +435,7 @@ class OfflineSimulatorResource(AQTResource):
     def __init__(
         self,
         provider: "AQTProvider",
-        resource_id: api_models.ResourceId,
+        resource_id: api_client.Resource,
         with_noise_model: bool,
     ) -> None:
         """Initialize an offline simulator resource.
diff --git a/qiskit_aqt_provider/persistence.py b/qiskit_aqt_provider/persistence.py
index 8c890a0..7312223 100644
--- a/qiskit_aqt_provider/persistence.py
+++ b/qiskit_aqt_provider/persistence.py
@@ -24,7 +24,7 @@
 from qiskit.circuit import QuantumCircuit
 from typing_extensions import Self
 
-from qiskit_aqt_provider.api_client.models import ResourceId
+from qiskit_aqt_provider.api_client import Resource
 from qiskit_aqt_provider.aqt_options import AQTOptions
 from qiskit_aqt_provider.utils import map_exceptions
 from qiskit_aqt_provider.versions import QISKIT_AQT_PROVIDER_VERSION
@@ -91,7 +91,7 @@ class Job(pdt.BaseModel):
 
     model_config = ConfigDict(frozen=True, json_encoders={Circuits: Circuits.json_encoder})
 
-    resource: ResourceId
+    resource: Resource
     circuits: Circuits
     options: AQTOptions
 
diff --git a/qiskit_aqt_provider/test/fixtures.py b/qiskit_aqt_provider/test/fixtures.py
index 5d1d4ee..1992b1c 100644
--- a/qiskit_aqt_provider/test/fixtures.py
+++ b/qiskit_aqt_provider/test/fixtures.py
@@ -27,6 +27,7 @@
 from qiskit_aer import AerSimulator
 from typing_extensions import override
 
+from qiskit_aqt_provider import api_client
 from qiskit_aqt_provider.api_client import models as api_models
 from qiskit_aqt_provider.api_client import models_direct as api_models_direct
 from qiskit_aqt_provider.aqt_job import AQTJob
@@ -47,7 +48,7 @@ def __init__(self, *, noisy: bool) -> None:
         """Initialize the mocked simulator backend."""
         super().__init__(
             AQTProvider(""),
-            resource_id=api_models.ResourceId(
+            resource_id=api_client.Resource(
                 workspace_id="default",
                 resource_id="mock_simulator",
                 resource_name="mock_simulator",
diff --git a/qiskit_aqt_provider/test/resources.py b/qiskit_aqt_provider/test/resources.py
index 47d72a9..8a4363a 100644
--- a/qiskit_aqt_provider/test/resources.py
+++ b/qiskit_aqt_provider/test/resources.py
@@ -22,6 +22,7 @@
 from qiskit import QuantumCircuit
 from typing_extensions import assert_never, override
 
+from qiskit_aqt_provider import api_client
 from qiskit_aqt_provider.api_client import models as api_models
 from qiskit_aqt_provider.aqt_job import AQTJob
 from qiskit_aqt_provider.aqt_provider import AQTProvider
@@ -151,7 +152,7 @@ def __init__(
         """
         super().__init__(
             AQTProvider(""),
-            resource_id=api_models.ResourceId(
+            resource_id=api_client.Resource(
                 workspace_id="test-workspace",
                 resource_id="test",
                 resource_name="test-resource",
@@ -222,7 +223,7 @@ def __init__(self, token: str) -> None:
         """Initialize the dummy backend."""
         super().__init__(
             AQTProvider(token),
-            resource_id=api_models.ResourceId(
+            resource_id=api_client.Resource(
                 workspace_id="dummy",
                 resource_id="dummy",
                 resource_name="dummy",
diff --git a/test/api_client/test_models.py b/test/api_client/test_models.py
index 672688a..3303637 100644
--- a/test/api_client/test_models.py
+++ b/test/api_client/test_models.py
@@ -10,10 +10,35 @@
 # copyright notice, and modified files need to carry a notice indicating
 # that they have been altered from the originals.
 
+import pytest
+
 from qiskit_aqt_provider.api_client import models as api_models
 from qiskit_aqt_provider.api_client import models_generated as api_models_generated
 
 
+def test_workspaces_container_empty() -> None:
+    """Test the empty edge case of the Workspaces container."""
+    empty = api_models.Workspaces(root=[])
+    assert len(empty) == 0
+
+    with pytest.raises(StopIteration):
+        next(iter(empty))
+
+    assert api_models.Workspace(workspace_id="w1", resources=[]) not in empty
+
+
+def test_workspaces_contains() -> None:
+    """Test the Workspaces.__contains__ implementation."""
+    workspaces = api_models.Workspaces(
+        root=[
+            api_models_generated.Workspace(id="w1", resources=[]),
+        ]
+    )
+
+    assert api_models.Workspace(workspace_id="w1", resources=[]) in workspaces
+    assert api_models.Workspace(workspace_id="w2", resources=[]) not in workspaces
+
+
 def test_workspaces_filter_by_workspace() -> None:
     """Test filtering the Workspaces model content by workspace ID."""
     workspaces = api_models.Workspaces(
@@ -24,10 +49,10 @@ def test_workspaces_filter_by_workspace() -> None:
     )
 
     filtered = workspaces.filter(workspace_pattern="^w")
-    assert {workspace.id for workspace in filtered.root} == {"w1", "w2"}
+    assert {workspace.workspace_id for workspace in filtered} == {"w1", "w2"}
 
     filtered = workspaces.filter(workspace_pattern="w1")
-    assert {workspace.id for workspace in filtered.root} == {"w1"}
+    assert {workspace.workspace_id for workspace in filtered} == {"w1"}
 
 
 def test_workspaces_filter_by_name() -> None:
@@ -38,10 +63,10 @@ def test_workspaces_filter_by_name() -> None:
                 id="w1",
                 resources=[
                     api_models_generated.Resource(
-                        id="r10", name="r10", type=api_models.ResourceType.device
+                        id="r10", name="r10", type=api_models_generated.Type.device
                     ),
                     api_models_generated.Resource(
-                        id="r20", name="r20", type=api_models.ResourceType.device
+                        id="r20", name="r20", type=api_models_generated.Type.device
                     ),
                 ],
             ),
@@ -49,7 +74,7 @@ def test_workspaces_filter_by_name() -> None:
                 id="w2",
                 resources=[
                     api_models_generated.Resource(
-                        id="r11", name="r11", type=api_models.ResourceType.simulator
+                        id="r11", name="r11", type=api_models_generated.Type.simulator
                     )
                 ],
             ),
@@ -64,7 +89,7 @@ def test_workspaces_filter_by_name() -> None:
                 id="w1",
                 resources=[
                     api_models_generated.Resource(
-                        id="r10", name="r10", type=api_models.ResourceType.device
+                        id="r10", name="r10", type=api_models_generated.Type.device
                     ),
                 ],
             ),
@@ -72,7 +97,7 @@ def test_workspaces_filter_by_name() -> None:
                 id="w2",
                 resources=[
                     api_models_generated.Resource(
-                        id="r11", name="r11", type=api_models.ResourceType.simulator
+                        id="r11", name="r11", type=api_models_generated.Type.simulator
                     )
                 ],
             ),
@@ -88,23 +113,23 @@ def test_workspaces_filter_by_backend_type() -> None:
                 id="w1",
                 resources=[
                     api_models_generated.Resource(
-                        id="r1", name="r1", type=api_models.ResourceType.device
+                        id="r1", name="r1", type=api_models_generated.Type.device
                     ),
                     api_models_generated.Resource(
-                        id="r2", name="r2", type=api_models.ResourceType.simulator
+                        id="r2", name="r2", type=api_models_generated.Type.simulator
                     ),
                 ],
             )
         ]
     )
 
-    filtered = workspaces.filter(backend_type=api_models.ResourceType.simulator)
-    assert len(filtered.root) == 1
-    assert filtered.root[0] == api_models_generated.Workspace(
-        id="w1",
+    filtered = workspaces.filter(backend_type="simulator")
+    assert len(filtered) == 1
+    assert next(iter(filtered)) == api_models.Workspace(
+        workspace_id="w1",
         resources=[
-            api_models_generated.Resource(
-                id="r2", name="r2", type=api_models.ResourceType.simulator
+            api_models.Resource(
+                workspace_id="w1", resource_id="r2", resource_name="r2", resource_type="simulator"
             )
         ],
     )
diff --git a/test/test_job_persistence.py b/test/test_job_persistence.py
index 32316fa..e5496aa 100644
--- a/test/test_job_persistence.py
+++ b/test/test_job_persistence.py
@@ -25,6 +25,7 @@
 from qiskit.providers import JobStatus
 
 from qiskit_aqt_provider import persistence
+from qiskit_aqt_provider.api_client import Resource
 from qiskit_aqt_provider.api_client import models as api_models
 from qiskit_aqt_provider.api_client import models_generated as api_models_generated
 from qiskit_aqt_provider.aqt_job import AQTJob
@@ -97,7 +98,7 @@ def test_job_persistence_transaction_online_backend(httpx_mock: HTTPXMock, tmp_p
     # Set up a fake online resource
     token = str(uuid.uuid4())
     provider = AQTProvider(token)
-    resource_id = api_models.ResourceId(
+    resource_id = Resource(
         workspace_id=str(uuid.uuid4()),
         resource_id=str(uuid.uuid4()),
         resource_name=str(uuid.uuid4()),
diff --git a/test/test_provider.py b/test/test_provider.py
index 280f493..bc5603c 100644
--- a/test/test_provider.py
+++ b/test/test_provider.py
@@ -17,11 +17,12 @@
 import uuid
 from pathlib import Path
 from unittest import mock
-from urllib.parse import urlparse
 
+import httpx
 import pytest
 from pytest_httpx import HTTPXMock
 
+from qiskit_aqt_provider.api_client import DEFAULT_PORTAL_URL
 from qiskit_aqt_provider.api_client import models as api_models
 from qiskit_aqt_provider.api_client import models_generated as api_models_generated
 from qiskit_aqt_provider.aqt_provider import OFFLINE_SIMULATORS, AQTProvider, NoTokenWarning
@@ -32,26 +33,18 @@ def test_default_portal_url() -> None:
     with mock.patch.object(os, "environ", {}):
         aqt = AQTProvider("my-token")
 
-    result = urlparse(aqt.portal_url)
-    expected = urlparse(AQTProvider.DEFAULT_PORTAL_URL)
-
-    assert result.scheme == expected.scheme
-    assert result.netloc == expected.netloc
+    assert aqt._portal_client.portal_url == DEFAULT_PORTAL_URL
 
 
 def test_portal_url_envvar(monkeypatch: pytest.MonkeyPatch) -> None:
     """Check that one can set the portal url via the environment variable."""
-    env_url = "https://new-portal.aqt.eu"
-    assert env_url != AQTProvider.DEFAULT_PORTAL_URL
-    monkeypatch.setenv("AQT_PORTAL_URL", env_url)
+    env_url = httpx.URL("https://new-portal.aqt.eu")
+    assert env_url != DEFAULT_PORTAL_URL
+    monkeypatch.setenv("AQT_PORTAL_URL", str(env_url))
 
     aqt = AQTProvider("my-token")
 
-    result = urlparse(aqt.portal_url)
-    expected = urlparse(env_url)
-
-    assert result.scheme == expected.scheme
-    assert result.netloc == expected.netloc
+    assert aqt._portal_client.portal_url == env_url
 
 
 def test_access_token_argument() -> None: