diff --git a/CHANGELOG.rst b/CHANGELOG.rst
index 1ad4fc80..9ee7a40f 100644
--- a/CHANGELOG.rst
+++ b/CHANGELOG.rst
@@ -2,6 +2,12 @@
 Changelog
 =========
 
+TBD
+===
+
+* Use ``web_poet.Unset`` sentinel value which represents fields which hasn't been
+  assigned with any value. This is to differentiate values which are ``None``.
+
 0.2.0 (2022-09-22)
 ==================
 
diff --git a/README.rst b/README.rst
index 6b6d955b..a30c3c95 100644
--- a/README.rst
+++ b/README.rst
@@ -20,12 +20,12 @@ zyte-common-items
 
 .. description starts
 
-``zyte-common-items`` is a Python 3.7+ library of item classes used by Zyte_ to
-normalize different types of data extracted from websites.
-
-It can be used in custom data extraction code for normalization purposes,
-maximizing opportunities for code reuse.
+``zyte-common-items`` is a Python 3.7+ library of item_ and `page object`_
+classes for web data extraction that we use at Zyte_ to maximize opportunities
+for code reuse.
 
+.. _item: https://docs.scrapy.org/en/latest/topics/items.html
+.. _page object: https://web-poet.readthedocs.io/en/stable/
 .. _Zyte: https://www.zyte.com/
 
 .. description ends
diff --git a/docs/conf.py b/docs/conf.py
index 3c86a9da..91eaf1b3 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -35,6 +35,8 @@ def get_version_and_release():
 
 autodoc_member_order = "groupwise"
 
+intersphinx_disabled_reftypes = []
 intersphinx_mapping = {
     "python": ("https://docs.python.org/3", None),
+    "web-poet": ("https://web-poet.readthedocs.io/en/stable", None),
 }
diff --git a/docs/index.rst b/docs/index.rst
index 7f2fd69b..79cda06f 100644
--- a/docs/index.rst
+++ b/docs/index.rst
@@ -7,10 +7,27 @@ zyte-common-items |version| documentation
    :end-before: .. description ends
 
 .. toctree::
-   :hidden:
+   :caption: Getting started
+   :maxdepth: 1
 
    setup
-   usage
+
+.. toctree::
+   :caption: Usage
+   :maxdepth: 1
+
+   usage/items
+   usage/pages
+
+.. toctree::
+   :caption: Reference
+   :maxdepth: 1
+
    reference/index
    changelog
+
+.. toctree::
+   :caption: Contributing
+   :maxdepth: 1
+
    contributing
diff --git a/docs/reference/adapter.rst b/docs/reference/adapter.rst
index 9add1131..f23fc23b 100644
--- a/docs/reference/adapter.rst
+++ b/docs/reference/adapter.rst
@@ -2,5 +2,4 @@
 Adapter
 =======
 
-.. class:: zyte_common_items.ZyteItemAdapter
-.. autoclass:: zyte_common_items.adapter.ZyteItemAdapter
\ No newline at end of file
+.. autoclass:: zyte_common_items.ZyteItemAdapter
\ No newline at end of file
diff --git a/docs/reference/components.rst b/docs/reference/components.rst
index 5e230a59..ef089bc4 100644
--- a/docs/reference/components.rst
+++ b/docs/reference/components.rst
@@ -7,34 +7,26 @@ Components
 These classes are used to map data within :ref:`items <items>`, and are not
 tied to any specific item type.
 
-.. class:: zyte_common_items.AdditionalProperty(**kwargs)
-.. autoclass:: zyte_common_items.components.AdditionalProperty(**kwargs)
+.. autoclass:: zyte_common_items.AdditionalProperty(**kwargs)
    :members:
 
-.. class:: zyte_common_items.AggregateRating(**kwargs)
-.. autoclass:: zyte_common_items.components.AggregateRating(**kwargs)
+.. autoclass:: zyte_common_items.AggregateRating(**kwargs)
    :members:
 
-.. class:: zyte_common_items.Brand(**kwargs)
-.. autoclass:: zyte_common_items.components.Brand(**kwargs)
+.. autoclass:: zyte_common_items.Brand(**kwargs)
    :members:
 
-.. class:: zyte_common_items.Breadcrumb(**kwargs)
-.. autoclass:: zyte_common_items.components.Breadcrumb(**kwargs)
+.. autoclass:: zyte_common_items.Breadcrumb(**kwargs)
    :members:
 
-.. class:: zyte_common_items.Gtin(**kwargs)
-.. autoclass:: zyte_common_items.components.Gtin(**kwargs)
+.. autoclass:: zyte_common_items.Gtin(**kwargs)
    :members:
 
-.. class:: zyte_common_items.Image(**kwargs)
-.. autoclass:: zyte_common_items.components.Image(**kwargs)
+.. autoclass:: zyte_common_items.Image(**kwargs)
    :members:
 
-.. class:: zyte_common_items.Link(**kwargs)
-.. autoclass:: zyte_common_items.components.Link(**kwargs)
+.. autoclass:: zyte_common_items.Link(**kwargs)
    :members:
 
-.. class:: zyte_common_items.Metadata(**kwargs)
-.. autoclass:: zyte_common_items.components.Metadata(**kwargs)
+.. autoclass:: zyte_common_items.Metadata(**kwargs)
    :members:
diff --git a/docs/reference/index.rst b/docs/reference/index.rst
index 4a5fe362..482b7e91 100644
--- a/docs/reference/index.rst
+++ b/docs/reference/index.rst
@@ -5,5 +5,6 @@ Reference
 .. toctree::
 
    items
+   pages
    components
    adapter
diff --git a/docs/reference/items.rst b/docs/reference/items.rst
index c3f712dc..24555180 100644
--- a/docs/reference/items.rst
+++ b/docs/reference/items.rst
@@ -1,32 +1,28 @@
-.. _items:
+.. _item-api:
 
-=====
-Items
-=====
+========
+Item API
+========
 
 Product
 =======
 
-.. class:: zyte_common_items.Product(**kwargs)
-.. autoclass:: zyte_common_items.items.Product(**kwargs)
+.. autoclass:: zyte_common_items.Product(**kwargs)
    :members:
    :inherited-members:
 
-.. class:: zyte_common_items.ProductVariant(**kwargs)
-.. autoclass:: zyte_common_items.items.ProductVariant(**kwargs)
+.. autoclass:: zyte_common_items.ProductVariant(**kwargs)
    :members:
    :inherited-members:
 
 Product List
 ============
 
-.. class:: zyte_common_items.ProductList(**kwargs)
-.. autoclass:: zyte_common_items.items.ProductList(**kwargs)
+.. autoclass:: zyte_common_items.ProductList(**kwargs)
    :members:
    :inherited-members:
 
-.. class:: zyte_common_items.ProductFromList(**kwargs)
-.. autoclass:: zyte_common_items.items.ProductFromList(**kwargs)
+.. autoclass:: zyte_common_items.ProductFromList(**kwargs)
    :members:
    :inherited-members:
 
@@ -34,10 +30,9 @@ Product List
 Custom items
 ============
 
-Subclass :class:`~zyte_common_items.base.Item` to create your own item classes.
+Subclass :class:`~zyte_common_items.Item` to create your own item classes.
 
-.. class:: zyte_common_items.Item(**kwargs)
-.. autoclass:: zyte_common_items.base.Item(**kwargs)
+.. autoclass:: zyte_common_items.Item(**kwargs)
    :members:
 
    .. attribute:: _unknown_fields_dict
diff --git a/docs/reference/pages.rst b/docs/reference/pages.rst
new file mode 100644
index 00000000..d2cdccf4
--- /dev/null
+++ b/docs/reference/pages.rst
@@ -0,0 +1,76 @@
+.. _page-object-api:
+
+===============
+Page object API
+===============
+
+Product
+=======
+
+.. autoclass:: zyte_common_items.BaseProductPage(**kwargs)
+   :show-inheritance:
+
+.. autoclass:: zyte_common_items.ProductPage(**kwargs)
+   :show-inheritance:
+
+
+Product List
+============
+
+.. autoclass:: zyte_common_items.BaseProductListPage(**kwargs)
+   :show-inheritance:
+
+.. autoclass:: zyte_common_items.ProductListPage(**kwargs)
+   :show-inheritance:
+
+
+Custom page objects
+===================
+
+Subclass :class:`~zyte_common_items.Page` to create your own page object
+classes that rely on :class:`~zyte_common_items.HttpResponse`.
+
+If you do not want :class:`~zyte_common_items.HttpResponse` as input, you can
+inherit from :class:`~zyte_common_items.BasePage` instead.
+
+.. autoclass:: zyte_common_items.BasePage(**kwargs)
+   :show-inheritance:
+
+   Base class for page object classes that has
+   :class:`~zyte_common_items.ResponseUrl` as a dependency.
+
+   .. data:: metadata
+      :type: zyte_common_items.Metadata
+
+      Data extraction process metadata.
+
+      :attr:`~zyte_common_items.Metadata.dateDownloaded` is set to the current
+      UTC date and time.
+
+      :attr:`~zyte_common_items.Metadata.probability` is set to ``1.0``.
+
+   .. data:: url
+      :type: web_poet.page_inputs.http.ResponseUrl
+
+      Main URL from which the data has been extracted.
+
+.. autoclass:: zyte_common_items.Page(**kwargs)
+   :show-inheritance:
+
+   Base class for page object classes that has
+   :class:`~zyte_common_items.HttpResponse` as a dependency.
+
+   .. data:: metadata
+      :type: zyte_common_items.Metadata
+
+      Data extraction process metadata.
+
+      :attr:`~zyte_common_items.Metadata.dateDownloaded` is set to the current
+      UTC date and time.
+
+      :attr:`~zyte_common_items.Metadata.probability` is set to ``1.0``.
+
+   .. data:: url
+      :type: web_poet.page_inputs.http.ResponseUrl
+
+      Main URL from which the data has been extracted.
diff --git a/docs/usage.rst b/docs/usage/items.rst
similarity index 96%
rename from docs/usage.rst
rename to docs/usage/items.rst
index 516acae5..1298df40 100644
--- a/docs/usage.rst
+++ b/docs/usage/items.rst
@@ -1,7 +1,12 @@
+.. _items:
+
 =====
-Usage
+Items
 =====
 
+The :ref:`provided item classes <item-api>` can be used to map data extracted
+from web pages, e.g. using :ref:`page objects <page-objects>`.
+
 Creating items from dictionaries
 ================================
 
@@ -31,6 +36,7 @@ nested data, such as :class:`~zyte_common_items.components.Image` and
 >>> product.mainImage
 Image(url='https://example.com/image.png')
 >>> product.canonicalUrl
+Unset
 >>> product.gtin
 [Gtin(type='gtin13', value='9504000059446')]
 
diff --git a/docs/usage/pages.rst b/docs/usage/pages.rst
new file mode 100644
index 00000000..749f4638
--- /dev/null
+++ b/docs/usage/pages.rst
@@ -0,0 +1,37 @@
+.. _page-objects:
+
+============
+Page objects
+============
+
+The :ref:`provided page object classes <page-object-api>` are good base classes
+for custom page object classes that implement website-specific :doc:`page
+objects <web-poet:index>`.
+
+They provide the following base line:
+
+-   They declare the :ref:`item class <items>` that they return, allowing for
+    their ``to_item`` method to automatically build an instance of it from
+    ``@field``-decorated methods. See :ref:`web-poet-fields`.
+
+-   They provide a default implementation for their
+    :attr:`~zyte_common_items.Page.metadata` and
+    :attr:`~zyte_common_items.Page.url` fields.
+
+The following code shows a :class:`~zyte_common_items.ProductPage` subclass
+whose ``to_item`` method returns an instance of
+:class:`~zyte_common_items.Product` with
+:attr:`~zyte_common_items.Product.metadata`, a
+:attr:`~zyte_common_items.Product.name`, and a
+:attr:`~zyte_common_items.Product.url`:
+
+.. code-block:: python
+
+   import attrs
+   from zyte_common_items import ProductPage
+
+    class CustomProductPage(ProductPage):
+
+        @field
+        def name(self):
+            return self.css("h1::text").get()
diff --git a/setup.py b/setup.py
index c35236d9..5f7ffa9e 100644
--- a/setup.py
+++ b/setup.py
@@ -25,7 +25,7 @@
     install_requires=[
         "attrs>=21.3.0",
         "itemadapter>=0.2.0",
-        "web-poet>=0.5.0",
+        "web-poet @ git+https://git@github.com/scrapinghub/web-poet@feat-unset#egg=web-poet",
     ],
     classifiers=[
         "Development Status :: 3 - Alpha",
diff --git a/tests/test_adapter.py b/tests/test_adapter.py
index c251603a..37573850 100644
--- a/tests/test_adapter.py
+++ b/tests/test_adapter.py
@@ -9,6 +9,7 @@
 import attrs
 import pytest
 from itemadapter import ItemAdapter
+from web_poet import Unset
 
 from zyte_common_items import Item, Product, ZyteItemAdapter
 
@@ -202,7 +203,7 @@ def test_known_field_get_missing():
     product = Product(url=url)
     with configured_adapter():
         adapter = ItemAdapter(product)
-        assert adapter["canonicalUrl"] is None
+        assert adapter["canonicalUrl"] is Unset
 
 
 def test_known_field_set():
diff --git a/tests/test_components.py b/tests/test_components.py
index 62582f36..5d4fce24 100644
--- a/tests/test_components.py
+++ b/tests/test_components.py
@@ -1,3 +1,5 @@
+from web_poet import Unset
+
 from zyte_common_items import AggregateRating, Breadcrumb, Link, Metadata
 
 
@@ -19,5 +21,5 @@ def test_link_optional_fields():
 
 def test_metadata_default_values():
     metadata = Metadata()
-    assert metadata.dateDownloaded is None
-    assert metadata.probability is None
+    assert metadata.dateDownloaded is Unset
+    assert metadata.probability is Unset
diff --git a/tests/test_items.py b/tests/test_items.py
index fe00ecf3..7262e7b1 100644
--- a/tests/test_items.py
+++ b/tests/test_items.py
@@ -1,6 +1,7 @@
 from copy import copy
 
 import pytest
+from web_poet import Unset
 
 from zyte_common_items import (
     AdditionalProperty,
@@ -119,7 +120,7 @@ def test_product_min_fields():
     for field in list(_PRODUCT_ALL_KWARGS):
         if field in _PRODUCT_MIN_KWARGS:
             continue
-        assert getattr(product, field) is None
+        assert getattr(product, field) is Unset
 
 
 def test_product_missing_fields():
@@ -141,7 +142,7 @@ def test_product_list_min_fields():
     for field in list(_PRODUCT_LIST_MIN_KWARGS):
         if field in _PRODUCT_LIST_MIN_KWARGS:
             continue
-        assert getattr(product_list, field) is None
+        assert getattr(product_list, field) is Unset
 
 
 def test_product_list_missing_fields():
@@ -161,7 +162,7 @@ def test_product_from_list_all_fields():
 def test_product_from_list_min_fields():
     product_from_list = ProductFromList()
     for field in list(_PRODUCT_FROM_LIST_ALL_KWARGS):
-        assert getattr(product_from_list, field) is None
+        assert getattr(product_from_list, field) is Unset
 
 
 def test_product_variant_all_fields():
@@ -173,4 +174,4 @@ def test_product_variant_all_fields():
 def test_product_variant_min_fields():
     product_variant = ProductVariant()
     for field in list(_PRODUCT_VARIANT_ALL_KWARGS):
-        assert getattr(product_variant, field) is None
+        assert getattr(product_variant, field) is Unset
diff --git a/tests/test_mypy.py b/tests/test_mypy.py
index 8e572bdd..af03bc7e 100644
--- a/tests/test_mypy.py
+++ b/tests/test_mypy.py
@@ -187,28 +187,28 @@ def test_assignment_product_variant():
 @pytest.mark.mypy_testing
 def test_instantiation_image():
     with pytest.raises(ValueError):
-        Image(url=123)  # E: Argument "url" to "Image" has incompatible type "int"; expected "Union[str, _Url]"
+        Image(url=123)  # E: Argument "url" to "Image" has incompatible type "int"; expected "Union[str, _Url, UnsetType]"
 
 
 @pytest.mark.mypy_testing
 def test_instantiation_breadcrumb():
     with pytest.raises(ValueError):
-        Breadcrumb(url=123)  # E: Argument "url" to "Breadcrumb" has incompatible type "int"; expected "Union[str, _Url, None]"
+        Breadcrumb(url=123)  # E: Argument "url" to "Breadcrumb" has incompatible type "int"; expected "Union[str, _Url, UnsetType, None]"
 
 
 @pytest.mark.mypy_testing
 def test_instantiation_link():
     with pytest.raises(ValueError):
-        Link(url=123)  # E: Argument "url" to "Link" has incompatible type "int"; expected "Union[str, _Url, None]"
+        Link(url=123)  # E: Argument "url" to "Link" has incompatible type "int"; expected "Union[str, _Url, UnsetType, None]"
 
 
 @pytest.mark.mypy_testing
 def test_instantiation_product_list():
     with pytest.raises(ValueError):
-        ProductList(url=123)  # E: Argument "url" to "ProductList" has incompatible type "int"; expected "Union[str, _Url]"
+        ProductList(url=123)  # E: Argument "url" to "ProductList" has incompatible type "int"; expected "Union[str, _Url, UnsetType]"
     with pytest.raises(ValueError):
         ProductList(
-            url="https://www.example.com", canonicalUrl=123  # E: Argument "canonicalUrl" to "ProductList" has incompatible type "int"; expected "Union[str, _Url, None]"
+            url="https://www.example.com", canonicalUrl=123  # E: Argument "canonicalUrl" to "ProductList" has incompatible type "int"; expected "Union[str, _Url, UnsetType, None]"
         )
 
 
@@ -216,7 +216,7 @@ def test_instantiation_product_list():
 def test_instantiation_product_from_list():
     with pytest.raises(ValueError):
         ProductFromList(
-            url=123  # E: Argument "url" to "ProductFromList" has incompatible type "int"; expected "Union[str, _Url, None]"
+            url=123  # E: Argument "url" to "ProductFromList" has incompatible type "int"; expected "Union[str, _Url, UnsetType, None]"
         )
 
 
@@ -224,9 +224,9 @@ def test_instantiation_product_from_list():
 def test_instantiation_product_variant():
     with pytest.raises(ValueError):
         ProductVariant(
-            url=123  # E: Argument "url" to "ProductVariant" has incompatible type "int"; expected "Union[str, _Url, None]"
+            url=123  # E: Argument "url" to "ProductVariant" has incompatible type "int"; expected "Union[str, _Url, UnsetType, None]"
         )
     with pytest.raises(ValueError):
         ProductVariant(
-            url="https://www.example.com", canonicalUrl=123  # E: Argument "canonicalUrl" to "ProductVariant" has incompatible type "int"; expected "Union[str, _Url, None]"
+            url="https://www.example.com", canonicalUrl=123  # E: Argument "canonicalUrl" to "ProductVariant" has incompatible type "int"; expected "Union[str, _Url, UnsetType, None]"
         )
diff --git a/tests/test_pages.py b/tests/test_pages.py
new file mode 100644
index 00000000..d9163ae9
--- /dev/null
+++ b/tests/test_pages.py
@@ -0,0 +1,103 @@
+from datetime import datetime
+
+import attrs
+import pytest
+from web_poet import HttpResponse, ResponseUrl, field
+
+from zyte_common_items import (
+    BaseProductListPage,
+    BaseProductPage,
+    ProductListPage,
+    ProductPage,
+)
+
+
+@pytest.mark.parametrize(
+    "page_class",
+    (
+        BaseProductPage,
+        BaseProductListPage,
+    ),
+)
+def test_base_pages_default(page_class):
+    datetime_before = datetime.utcnow().replace(microsecond=0)
+
+    page = page_class(url=ResponseUrl("https://example.com"))
+
+    assert page.metadata.probability == 1.0
+    assert page.url == "https://example.com"
+    assert isinstance(page.url, str)
+
+    page_datetime_string = page.metadata.dateDownloaded
+    assert page_datetime_string.endswith("Z")
+    page_datetime = datetime.fromisoformat(page_datetime_string[:-1])
+    datetime_after = datetime.utcnow().replace(microsecond=0)
+    assert datetime_before <= page_datetime <= datetime_after
+
+
+@pytest.mark.parametrize(
+    "page_class",
+    (
+        ProductPage,
+        ProductListPage,
+    ),
+)
+def test_pages_default(page_class):
+    datetime_before = datetime.utcnow().replace(microsecond=0)
+
+    url = ResponseUrl("https://example.com")
+    html = b"""
+    <!DOCTYPE html>
+    <html>
+        <body>
+            <h1>Foo</h1>
+        </body>
+    </html>
+    """
+    response = HttpResponse(url=url, body=html)
+
+    page = page_class(response=response)
+
+    assert page.metadata.probability == 1.0
+    assert page.url == "https://example.com"
+    assert isinstance(page.url, str)
+
+    page_datetime_string = page.metadata.dateDownloaded
+    assert page_datetime_string.endswith("Z")
+    page_datetime = datetime.fromisoformat(page_datetime_string[:-1])
+    datetime_after = datetime.utcnow().replace(microsecond=0)
+    assert datetime_before <= page_datetime <= datetime_after
+
+
+@pytest.mark.asyncio
+async def test_example():
+    datetime_before = datetime.utcnow().replace(microsecond=0)
+
+    @attrs.define
+    class BookPage(ProductPage):
+        @field
+        def name(self):
+            return self.css("h1::text").get()
+
+    url = ResponseUrl("https://example.com/books/1")
+    html = b"""
+    <!DOCTYPE html>
+    <html>
+        <body>
+            <h1>Foo</h1>
+        </body>
+    </html>
+    """
+    response = HttpResponse(url=url, body=html)
+
+    item = await BookPage(response=response).to_item()
+
+    assert item.url == str(url)
+    assert item.name == "Foo"
+    assert item.metadata.probability == 1.0
+
+    item_datetime_string = item.metadata.dateDownloaded
+    assert item_datetime_string.endswith("Z")
+    item_datetime = datetime.fromisoformat(item_datetime_string[:-1])
+    datetime_after = datetime.utcnow().replace(microsecond=0)
+    assert datetime_before <= item_datetime <= datetime_after
diff --git a/tox.ini b/tox.ini
index 0b92512d..aa62e981 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,11 +1,14 @@
 [tox]
-envlist = py37,py38,py39,py310,mypy
+envlist = py37,py38,py39,py310,mypy,docs
 
 [testenv]
 deps =
     pytest
+    pytest-asyncio
     pytest-cov
-    pytest-mypy-testing==0.0.11
+    # https://github.com/davidfritzsche/pytest-mypy-testing/issues/35
+    git+https://github.com/davidfritzsche/pytest-mypy-testing.git@031514ff6ecd5bdf4d11ff238c14d4801b5e47f3
+    mypy==0.971
 setenv =
     PY_IGNORE_IMPORTMISMATCH=1
 commands =
diff --git a/zyte_common_items/__init__.py b/zyte_common_items/__init__.py
index c958cc8c..c389a534 100644
--- a/zyte_common_items/__init__.py
+++ b/zyte_common_items/__init__.py
@@ -12,3 +12,11 @@
     Metadata,
 )
 from .items import Product, ProductFromList, ProductList, ProductVariant
+from .pages import (
+    BasePage,
+    BaseProductListPage,
+    BaseProductPage,
+    Page,
+    ProductListPage,
+    ProductPage,
+)
diff --git a/zyte_common_items/base.py b/zyte_common_items/base.py
index 313019a8..ef74b6d7 100644
--- a/zyte_common_items/base.py
+++ b/zyte_common_items/base.py
@@ -6,19 +6,20 @@
     from typing import get_args
 except ImportError:
     # Compliance with python 3.7
-    from zyte_common_items.util import get_args
+    from .util import get_args
 
 try:
     from typing import get_origin
 except ImportError:
     # Compliance with python 3.7
-    from zyte_common_items.util import get_origin
+    from .util import get_origin
 
 from typing import Dict, List, Optional, Union
 
 import attrs
+from web_poet import UnsetType
 
-from zyte_common_items.util import split_in_unknown_and_known_fields
+from .util import split_in_unknown_and_known_fields
 
 
 def is_data_container(cls_or_obj):
@@ -88,9 +89,12 @@ def _apply_field_types_to_sub_fields(cls, item: Dict):
             origin = get_origin(type_annotation)
             if origin == Union:
                 field_classes = get_args(type_annotation)
-                if len(field_classes) != 2 or not isinstance(None, field_classes[1]):
+                if len(field_classes) != 2 and not {UnsetType, type(None)} <= set(
+                    field_classes
+                ):
                     raise ValueError(
-                        "Field should only be annotated with one type (or optional)."
+                        "Field should only be annotated with one type "
+                        "(or either None or Unset)."
                     )
                 type_annotation = field_classes[0]
                 origin = get_origin(type_annotation)
diff --git a/zyte_common_items/components.py b/zyte_common_items/components.py
index 1ec481f2..b4c5af55 100644
--- a/zyte_common_items/components.py
+++ b/zyte_common_items/components.py
@@ -1,8 +1,9 @@
 """Classes for data nested within items."""
 
-from typing import Optional
+from typing import Union
 
 import attrs
+from web_poet import Unset, UnsetType
 
 from zyte_common_items.base import Item
 from zyte_common_items.util import url_to_str
@@ -34,13 +35,13 @@ class AggregateRating(Item):
     """
 
     #: Maximum value of the rating system.
-    bestRating: Optional[float] = None
+    bestRating: Union[float, None, UnsetType] = Unset
 
     #: Average value of all ratings.
-    ratingValue: Optional[float] = None
+    ratingValue: Union[float, None, UnsetType] = Unset
 
     #: Review count.
-    reviewCount: Optional[int] = None
+    reviewCount: Union[int, None, UnsetType] = Unset
 
 
 @attrs.define
@@ -65,11 +66,11 @@ class Breadcrumb(Item):
     """
 
     #: Displayed name.
-    name: Optional[str] = None
+    name: Union[str, None, UnsetType] = Unset
 
     #: Target URL.
-    url: Optional[str] = attrs.field(
-        default=None, converter=attrs.converters.optional(url_to_str), kw_only=True
+    url: Union[str, None, UnsetType] = attrs.field(
+        default=Unset, converter=attrs.converters.optional(url_to_str), kw_only=True
     )
 
 
@@ -119,11 +120,11 @@ class Link(Item):
     """A link from a webpage to another webpage."""
 
     #: Displayed text.
-    text: Optional[str] = None
+    text: Union[str, None, UnsetType] = Unset
 
     #: Target URL.
-    url: Optional[str] = attrs.field(
-        default=None, converter=attrs.converters.optional(url_to_str), kw_only=True
+    url: Union[str, None, UnsetType] = attrs.field(
+        default=Unset, converter=attrs.converters.optional(url_to_str), kw_only=True
     )
 
 
@@ -136,7 +137,7 @@ class Metadata(Item):
 
     #: Date and time when the product data was downloaded, in UTC timezone and
     #: the following format: ``YYYY-MM-DDThh:mm:ssZ``.
-    dateDownloaded: Optional[str] = None
+    dateDownloaded: Union[str, None, UnsetType] = Unset
 
     #: The probability (0 for 0%, 1 for 100%) that the webpage features the
     #: requested data type.
@@ -147,4 +148,4 @@ class Metadata(Item):
     #: webpage features a job listing instead of a product, the value should be
     #: `0`. When there is no complete certainty, the value could be anything in
     #: between (e.g. `0.96`).
-    probability: Optional[float] = None
+    probability: Union[str, None, UnsetType] = Unset
diff --git a/zyte_common_items/items.py b/zyte_common_items/items.py
index 37a8ad9e..f7f45f9a 100644
--- a/zyte_common_items/items.py
+++ b/zyte_common_items/items.py
@@ -1,6 +1,7 @@
-from typing import List, Optional
+from typing import List, Union
 
 import attrs
+from web_poet import Unset, UnsetType
 
 from zyte_common_items.base import Item
 from zyte_common_items.components import (
@@ -33,18 +34,18 @@ class ProductVariant(Item):
     #: extracted.
     #:
     #: See also ``features``.
-    additionalProperties: Optional[List[AdditionalProperty]] = None
+    additionalProperties: Union[List[AdditionalProperty], None, UnsetType] = Unset
 
     #: Availability status.
     #:
     #: The value is expected to be one of: ``"InStock"``, ``"OutOfStock"``.
-    availability: Optional[str] = None
+    availability: Union[str, None, UnsetType] = Unset
 
     #: Canonical form of the URL, as indicated by the website.
     #:
     #: See also ``url``.
-    canonicalUrl: Optional[str] = attrs.field(
-        default=None, converter=attrs.converters.optional(url_to_str), kw_only=True
+    canonicalUrl: Union[str, None, UnsetType] = attrs.field(
+        default=Unset, converter=attrs.converters.optional(url_to_str), kw_only=True
     )
 
     #: Color.
@@ -52,20 +53,20 @@ class ProductVariant(Item):
     #: It is extracted as displayed (e.g. ``"white"``).
     #:
     #: See also ``size``, ``style``.
-    color: Optional[str] = None
+    color: Union[str, None, UnsetType] = Unset
 
     #: Price currency `ISO 4217`_ alphabetic code (e.g. ``"USD"``).
     #:
     #: See also ``currencyRaw``.
     #:
     #: .. _ISO 4217: https://en.wikipedia.org/wiki/ISO_4217
-    currency: Optional[str] = None
+    currency: Union[str, None, UnsetType] = Unset
 
     #: Price currency as it appears on the webpage (no post-processing), e.g.
     #: ``"$"``.
     #:
     #: See also ``currency``.
-    currencyRaw: Optional[str] = None
+    currencyRaw: Union[str, None, UnsetType] = Unset
 
     #: List of standardized GTIN_ product identifiers associated with the
     #: product, which are unique for the product across different sellers.
@@ -73,17 +74,17 @@ class ProductVariant(Item):
     #: See also: ``mpn``, ``productId``, ``sku``.
     #:
     #: .. _GTIN: https://en.wikipedia.org/wiki/Global_Trade_Item_Number
-    gtin: Optional[List[Gtin]] = None
+    gtin: Union[List[Gtin], None, UnsetType] = Unset
 
     #: All product images.
     #:
     #: The main image (see ``mainImage``) should be first in the list.
     #:
     #: Images only displayed as part of the product description are excluded.
-    images: Optional[List[Image]] = None
+    images: Union[List[Image], None, UnsetType] = Unset
 
     #: Main product image.
-    mainImage: Optional[Image] = None
+    mainImage: Union[Image, None, UnsetType] = Unset
 
     #: `Manufacturer part number (MPN)`_.
     #:
@@ -92,10 +93,10 @@ class ProductVariant(Item):
     #: See also: ``gtin``, ``productId``, ``sku``.
     #:
     #: .. _Manufacturer part number (MPN): https://en.wikipedia.org/wiki/Part_number
-    mpn: Optional[str] = None
+    mpn: Union[str, None, UnsetType] = Unset
 
     #: Name as it appears on the webpage (no post-processing).
-    name: Optional[str] = None
+    name: Union[str, None, UnsetType] = Unset
 
     #: Price at which the product is being offered.
     #:
@@ -105,7 +106,7 @@ class ProductVariant(Item):
     #:
     #: If ``regularPrice`` is not ``None``, ``price`` should always be lower
     #: than ``regularPrice``.
-    price: Optional[str] = None
+    price: Union[str, None, UnsetType] = Unset
 
     #: Product identifier, unique within an e-commerce website.
     #:
@@ -113,7 +114,7 @@ class ProductVariant(Item):
     #: even a URL.
     #:
     #: See also: ``gtin``, ``mpn``, ``sku``.
-    productId: Optional[str] = None
+    productId: Union[str, None, UnsetType] = Unset
 
     #: Price at which the product was being offered in the past, and which is
     #: presented as a reference next to the current price.
@@ -125,7 +126,7 @@ class ProductVariant(Item):
     #:
     #: If ``regularPrice`` is not ``None``, it should always be higher than
     #: ``price``.
-    regularPrice: Optional[str] = None
+    regularPrice: Union[str, None, UnsetType] = Unset
 
     #: Size or dimensions.
     #:
@@ -134,7 +135,7 @@ class ProductVariant(Item):
     #: It is extracted as displayed (e.g. ``"XL"``).
     #:
     #: See also ``color``, ``style``.
-    size: Optional[str] = None
+    size: Union[str, None, UnsetType] = Unset
 
     #: `Stock keeping unit (SKU)`_ identifier, i.e. a merchant-specific product
     #: identifier.
@@ -142,7 +143,7 @@ class ProductVariant(Item):
     #: See also: ``gtin``, ``mpn``, ``productId``.
     #:
     #: .. _Stock keeping unit (SKU): https://en.wikipedia.org/wiki/Stock_keeping_unit
-    sku: Optional[str] = None
+    sku: Union[str, None, UnsetType] = Unset
 
     #: Style.
     #:
@@ -151,13 +152,13 @@ class ProductVariant(Item):
     #: It is extracted as displayed (e.g. ``"polka dots"``).
     #:
     #: See also ``color``, ``size``.
-    style: Optional[str] = None
+    style: Union[str, None, UnsetType] = Unset
 
     #: Main URL from which the product variant data could be extracted.
     #:
     #: See also ``canonicalUrl``.
-    url: Optional[str] = attrs.field(
-        default=None, converter=attrs.converters.optional(url_to_str), kw_only=True
+    url: Union[str, None, UnsetType] = attrs.field(
+        default=Unset, converter=attrs.converters.optional(url_to_str), kw_only=True
     )
 
 
@@ -179,29 +180,29 @@ class Product(Item):
     #: extracted.
     #:
     #: See also ``features``.
-    additionalProperties: Optional[List[AdditionalProperty]] = None
+    additionalProperties: Union[List[AdditionalProperty], None, UnsetType] = Unset
 
     #: Aggregate data about reviews and ratings.
-    aggregateRating: Optional[AggregateRating] = None
+    aggregateRating: Union[AggregateRating, None, UnsetType] = Unset
 
     #: Availability status.
     #:
     #: The value is expected to be one of: ``"InStock"``, ``"OutOfStock"``.
-    availability: Optional[str] = None
+    availability: Union[str, None, UnsetType] = Unset
 
     #: Brand.
-    brand: Optional[Brand] = None
+    brand: Union[Brand, None, UnsetType] = Unset
 
     #: Webpage `breadcrumb trail`_.
     #:
     #: .. _Breadcrumb trail: https://en.wikipedia.org/wiki/Breadcrumb_navigation
-    breadcrumbs: Optional[List[Breadcrumb]] = None
+    breadcrumbs: Union[List[Breadcrumb], None, UnsetType] = Unset
 
     #: Canonical form of the URL, as indicated by the website.
     #:
     #: See also ``url``.
-    canonicalUrl: Optional[str] = attrs.field(
-        default=None, converter=attrs.converters.optional(url_to_str), kw_only=True
+    canonicalUrl: Union[str, None, UnsetType] = attrs.field(
+        default=Unset, converter=attrs.converters.optional(url_to_str), kw_only=True
     )
 
     #: Color.
@@ -209,20 +210,20 @@ class Product(Item):
     #: It is extracted as displayed (e.g. ``"white"``).
     #:
     #: See also ``size``, ``style``.
-    color: Optional[str] = None
+    color: Union[str, None, UnsetType] = Unset
 
     #: Price currency `ISO 4217`_ alphabetic code (e.g. ``"USD"``).
     #:
     #: See also ``currencyRaw``.
     #:
     #: .. _ISO 4217: https://en.wikipedia.org/wiki/ISO_4217
-    currency: Optional[str] = None
+    currency: Union[str, None, UnsetType] = Unset
 
     #: Price currency as it appears on the webpage (no post-processing), e.g.
     #: ``"$"``.
     #:
     #: See also ``currency``.
-    currencyRaw: Optional[str] = None
+    currencyRaw: Union[str, None, UnsetType] = Unset
 
     #: Plain-text description.
     #:
@@ -243,7 +244,7 @@ class Product(Item):
     #: -   There should be no whitespace at the beginning or end.
     #:
     #: See also ``descriptionHtml``.
-    description: Optional[str] = None
+    description: Union[str, None, UnsetType] = Unset
 
     #: HTML description.
     #:
@@ -253,14 +254,14 @@ class Product(Item):
     #: normalization specification`_ for details.
     #:
     #: .. _HTML normalization specification: https://docs.zyte.com/automatic-extraction/article.html#format-of-articlebodyhtml-field
-    descriptionHtml: Optional[str] = None
+    descriptionHtml: Union[str, None, UnsetType] = Unset
 
     #: List of features.
     #:
     #: They are usually listed as bullet points in product webpages.
     #:
     #: See also ``additionalProperties``.
-    features: Optional[List[str]] = None
+    features: Union[List[str], None, UnsetType] = Unset
 
     #: List of standardized GTIN_ product identifiers associated with the
     #: product, which are unique for the product across different sellers.
@@ -268,20 +269,20 @@ class Product(Item):
     #: See also: ``mpn``, ``productId``, ``sku``.
     #:
     #: .. _GTIN: https://en.wikipedia.org/wiki/Global_Trade_Item_Number
-    gtin: Optional[List[Gtin]] = None
+    gtin: Union[List[Gtin], None, UnsetType] = Unset
 
     #: All product images.
     #:
     #: The main image (see ``mainImage``) should be first in the list.
     #:
     #: Images only displayed as part of the product description are excluded.
-    images: Optional[List[Image]] = None
+    images: Union[List[Image], None, UnsetType] = Unset
 
     #: Main product image.
-    mainImage: Optional[Image] = None
+    mainImage: Union[Image, None, UnsetType] = Unset
 
     #: Data extraction process metadata.
-    metadata: Optional[Metadata] = None
+    metadata: Union[Metadata, None, UnsetType] = Unset
 
     #: `Manufacturer part number (MPN)`_.
     #:
@@ -290,10 +291,10 @@ class Product(Item):
     #: See also: ``gtin``, ``productId``, ``sku``.
     #:
     #: .. _Manufacturer part number (MPN): https://en.wikipedia.org/wiki/Part_number
-    mpn: Optional[str] = None
+    mpn: Union[str, None, UnsetType] = Unset
 
     #: Name as it appears on the webpage (no post-processing).
-    name: Optional[str] = None
+    name: Union[str, None, UnsetType] = Unset
 
     #: Price at which the product is being offered.
     #:
@@ -303,7 +304,7 @@ class Product(Item):
     #:
     #: If ``regularPrice`` is not ``None``, ``price`` should always be lower
     #: than ``regularPrice``.
-    price: Optional[str] = None
+    price: Union[str, None, UnsetType] = Unset
 
     # Redefined to extend the documentation.
     #: Product identifier, unique within an e-commerce website.
@@ -312,7 +313,7 @@ class Product(Item):
     #: even a URL.
     #:
     #: See also: ``gtin``, ``mpn``, ``sku``.
-    productId: Optional[str] = None
+    productId: Union[str, None, UnsetType] = Unset
 
     #: Price at which the product was being offered in the past, and which is
     #: presented as a reference next to the current price.
@@ -324,7 +325,7 @@ class Product(Item):
     #:
     #: If ``regularPrice`` is not ``None``, it should always be higher than
     #: ``price``.
-    regularPrice: Optional[str] = None
+    regularPrice: Union[str, None, UnsetType] = Unset
 
     #: Size or dimensions.
     #:
@@ -333,7 +334,7 @@ class Product(Item):
     #: It is extracted as displayed (e.g. ``"XL"``).
     #:
     #: See also ``color``, ``style``.
-    size: Optional[str] = None
+    size: Union[str, None, UnsetType] = Unset
 
     #: `Stock keeping unit (SKU)`_ identifier, i.e. a merchant-specific product
     #: identifier.
@@ -341,7 +342,7 @@ class Product(Item):
     #: See also: ``gtin``, ``mpn``, ``productId``.
     #:
     #: .. _Stock keeping unit (SKU): https://en.wikipedia.org/wiki/Stock_keeping_unit
-    sku: Optional[str] = None
+    sku: Union[str, None, UnsetType] = Unset
 
     #: Style.
     #:
@@ -350,7 +351,7 @@ class Product(Item):
     #: It is extracted as displayed (e.g. ``"polka dots"``).
     #:
     #: See also ``color``, ``size``.
-    style: Optional[str] = None
+    style: Union[str, None, UnsetType] = Unset
 
     #: Main URL from which the data has been extracted.
     #:
@@ -382,7 +383,7 @@ class Product(Item):
     #:
     #: Product variant details may not include those that require multiple
     #: additional requests (e.g. 1 or more requests per variant).
-    variants: Optional[List[ProductVariant]] = None
+    variants: Union[List[ProductVariant], None, UnsetType] = Unset
 
 
 @attrs.define(slots=True, kw_only=True)
@@ -398,22 +399,22 @@ class ProductFromList(Item):
     #: See also ``currencyRaw``.
     #:
     #: .. _ISO 4217: https://en.wikipedia.org/wiki/ISO_4217
-    currency: Optional[str] = None
+    currency: Union[str, None, UnsetType] = Unset
 
     #: Price currency as it appears on the webpage (no post-processing), e.g.
     #: ``"$"``.
     #:
     #: See also ``currency``.
-    currencyRaw: Optional[str] = None
+    currencyRaw: Union[str, None, UnsetType] = Unset
 
     #: Main product image.
-    mainImage: Optional[Image] = None
+    mainImage: Union[Image, None, UnsetType] = Unset
 
     #: Data extraction process metadata.
-    metadata: Optional[Metadata] = None
+    metadata: Union[Metadata, None, UnsetType] = Unset
 
     #: Name as it appears on the webpage (no post-processing).
-    name: Optional[str] = None
+    name: Union[str, None, UnsetType] = Unset
 
     #: Price at which the product is being offered.
     #:
@@ -423,13 +424,13 @@ class ProductFromList(Item):
     #:
     #: If ``regularPrice`` is not ``None``, ``price`` should always be lower
     #: than ``regularPrice``.
-    price: Optional[str] = None
+    price: Union[str, None, UnsetType] = Unset
 
     #: Product identifier, unique within an e-commerce website.
     #:
     #: It may come in the form of an SKU or any other identifier, a hash, or
     #: even a URL.
-    productId: Optional[str] = None
+    productId: Union[str, None, UnsetType] = Unset
 
     #: Price at which the product was being offered in the past, and which is
     #: presented as a reference next to the current price.
@@ -441,11 +442,11 @@ class ProductFromList(Item):
     #:
     #: If ``regularPrice`` is not ``None``, it should always be higher than
     #: ``price``.
-    regularPrice: Optional[str] = None
+    regularPrice: Union[str, None, UnsetType] = Unset
 
     #: Main URL from which the product data could be extracted.
-    url: Optional[str] = attrs.field(
-        default=None, converter=attrs.converters.optional(url_to_str), kw_only=True
+    url: Union[str, None, UnsetType] = attrs.field(
+        default=Unset, converter=attrs.converters.optional(url_to_str), kw_only=True
     )
 
 
@@ -462,13 +463,13 @@ class ProductList(Item):
     #: Webpage `breadcrumb trail`_.
     #:
     #: .. _Breadcrumb trail: https://en.wikipedia.org/wiki/Breadcrumb_navigation
-    breadcrumbs: Optional[List[Breadcrumb]] = None
+    breadcrumbs: Union[List[Breadcrumb], None, UnsetType] = Unset
 
     #: Canonical form of the URL, as indicated by the website.
     #:
     #: See also ``url``.
-    canonicalUrl: Optional[str] = attrs.field(
-        default=None, converter=attrs.converters.optional(url_to_str), kw_only=True
+    canonicalUrl: Union[str, None, UnsetType] = attrs.field(
+        default=Unset, converter=attrs.converters.optional(url_to_str), kw_only=True
     )
 
     #: Name of the product listing as it appears on the webpage
@@ -476,10 +477,10 @@ class ProductList(Item):
     #:
     #: For example, if the webpage is one of the pages of the Robots category,
     #: ``categoryName`` is ``'Robots'``.
-    categoryName: Optional[str] = None
+    categoryName: Union[str, None, UnsetType] = Unset
 
     #: Data extraction process metadata.
-    metadata: Optional[Metadata] = None
+    metadata: Union[Metadata, None, UnsetType] = Unset
 
     #: Number of the current page.
     #:
@@ -487,10 +488,10 @@ class ProductList(Item):
     #:
     #: It must be 1-based. For example, if the first page of a listing is
     #: numbered as 0 on the website, it should be extracted as `1` nonetheless.
-    pageNumber: Optional[int] = None
+    pageNumber: Union[int, None, UnsetType] = Unset
 
     #: Link to the next page.
-    paginationNext: Optional[Link] = None
+    paginationNext: Union[Link, None, UnsetType] = Unset
 
     #: List of products.
     #:
@@ -501,7 +502,7 @@ class ProductList(Item):
     #: The order of the products reflects their position on the rendered page.
     #: Product order is top-to-bottom, and left-to-right or right-to-left
     #: depending on the webpage locale.
-    products: Optional[List[ProductFromList]] = None
+    products: Union[List[ProductFromList], None, UnsetType] = Unset
 
     #: Main URL from which the data has been extracted.
     #:
diff --git a/zyte_common_items/pages.py b/zyte_common_items/pages.py
new file mode 100644
index 00000000..6db8b9c2
--- /dev/null
+++ b/zyte_common_items/pages.py
@@ -0,0 +1,53 @@
+from datetime import datetime
+
+import attrs
+from web_poet import ItemPage, ResponseUrl, Returns, WebPage, field
+
+from .components import Metadata
+from .items import Product, ProductList
+
+
+class _BaseMixin:
+    def _get_response_url(self):
+        raise NotImplementedError
+
+    @field
+    def metadata(self) -> Metadata:
+        return Metadata(
+            dateDownloaded=f"{datetime.utcnow().isoformat(timespec='seconds')}Z",
+            probability=1.0,
+        )
+
+    @field
+    def url(self) -> str:
+        return str(self._get_response_url())
+
+
+@attrs.define
+class BasePage(_BaseMixin, ItemPage):
+    _url: ResponseUrl
+
+    def _get_response_url(self):
+        return self._url
+
+
+class BaseProductPage(BasePage, Returns[Product]):
+    pass
+
+
+class BaseProductListPage(BasePage, Returns[ProductList]):
+    pass
+
+
+@attrs.define
+class Page(_BaseMixin, WebPage):
+    def _get_response_url(self):
+        return self.response.url
+
+
+class ProductPage(Page, Returns[Product]):
+    pass
+
+
+class ProductListPage(Page, Returns[ProductList]):
+    pass
diff --git a/zyte_common_items/util.py b/zyte_common_items/util.py
index 6b088a96..743fd8d1 100644
--- a/zyte_common_items/util.py
+++ b/zyte_common_items/util.py
@@ -2,6 +2,7 @@
 from weakref import WeakKeyDictionary
 
 import attrs
+from web_poet import UnsetType
 from web_poet.page_inputs.url import _Url
 
 # Caches the attribute names for attr.s classes
@@ -59,7 +60,9 @@ def get_origin(tp) -> Tuple:
     return getattr(tp, "__origin__", ())
 
 
-def url_to_str(url: Union[str, _Url]) -> str:
+def url_to_str(url: Union[str, _Url, UnsetType]) -> Union[str, UnsetType]:
+    if isinstance(url, UnsetType):
+        return url
     if not isinstance(url, (str, _Url)):
         raise ValueError(
             f"{url!r} is neither a string nor an instance of RequestURL or ResponseURL."