diff --git a/docs/source/conf.py b/docs/source/conf.py
index 368ec8b..c4f89b7 100644
--- a/docs/source/conf.py
+++ b/docs/source/conf.py
@@ -14,7 +14,19 @@
 # -- General configuration ---------------------------------------------------
 # https://www.sphinx-doc.org/en/master/usage/configuration.html#general-configuration
 
-extensions = []
+extensions = [
+    # built-in extensions
+    "sphinx.ext.apidoc",  # generate API docs
+    "sphinx.ext.autodoc",  # include documentation from docstrings
+    "sphinx.ext.duration",  # show durations in documentation builds
+    "sphinx.ext.intersphinx",  # link to other projects' documentation
+    "sphinx.ext.mathjax",  # render math with MathJax
+    "sphinx.ext.napoleon",  # support numpy and google style docstrings
+    "sphinx.ext.viewcode",  # add links to highlighted source code
+    # other 3rd party extensions
+    "notfound.extension",  # adds a notfound 404 page
+    "sphinx_copybutton",  # adds a button that enables code to be copied
+]
 
 templates_path = ["_templates"]
 exclude_patterns = []
diff --git a/docs/source/index.rst b/docs/source/index.rst
index f322adb..1d77a06 100644
--- a/docs/source/index.rst
+++ b/docs/source/index.rst
@@ -8,3 +8,5 @@ documentation for details.
 .. toctree::
    :maxdepth: 2
    :caption: Contents:
+
+   utils
diff --git a/docs/source/utils.rst b/docs/source/utils.rst
new file mode 100644
index 0000000..439d893
--- /dev/null
+++ b/docs/source/utils.rst
@@ -0,0 +1,11 @@
+.. _utils:
+
+=================
+Package utilities
+=================
+
+.. module:: pyfaradaycup.utils
+.. currentmodule:: pyfaradaycup.utils
+
+.. automodapi:: pyfaradaycup.utils
+   :noindex:
diff --git a/noxfile.py b/noxfile.py
index fc0b1ee..9ecfbd8 100644
--- a/noxfile.py
+++ b/noxfile.py
@@ -46,7 +46,12 @@
 def tests(session: nox.Session) -> None:
     """Run tests with pytest."""
     session.install(".")
-    session.run("pytest", *session.posargs)
+
+    # Test examples in docstrings only using the most recent Python
+    # because string representations may change.
+    doctest_options = ["--doctest-modules"] if session.python == MAXPYTHON else []
+
+    session.run("pytest", *doctest_options, *session.posargs)
 
 
 if RUNNING_ON_RTD:
diff --git a/pyproject.toml b/pyproject.toml
index be859cd..49564c6 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -27,6 +27,7 @@ dependencies = [
 
 [dependency-groups]
 dev = [
+  { include-group = "docs" },
   { include-group = "lint" },
   { include-group = "nox" },
   { include-group = "test" },
@@ -40,6 +41,8 @@ test = [
 ]
 docs = [
   "sphinx>=9.1",
+  "sphinx-copybutton>=0.5.2",
+  "sphinx-notfound-page>=1.1",
 ]
 lint = [
   "pre-commit>=4.6.2",
diff --git a/src/pyfaradaycup/__init__.py b/src/pyfaradaycup/__init__.py
index 188e0be..a83ca36 100644
--- a/src/pyfaradaycup/__init__.py
+++ b/src/pyfaradaycup/__init__.py
@@ -1,9 +1,5 @@
-def hello() -> str:
-    """Check that docstrings are tested.
+"""Faraday cup data pipeline and data analysis tools."""
 
-    Examples
-    --------
-    >>> 6 * 9
-    54
-    """
-    return "Hello from pyfaradaycup!"
+__all__: list[str] = ["utils"]
+
+from pyfaradaycup import utils
diff --git a/src/pyfaradaycup/utils/__init__.py b/src/pyfaradaycup/utils/__init__.py
new file mode 100644
index 0000000..801aeab
--- /dev/null
+++ b/src/pyfaradaycup/utils/__init__.py
@@ -0,0 +1,17 @@
+"""Package utilities."""
+
+__all__: list[str] = ["placeholder"]
+
+from typing import Literal
+
+
+def placeholder() -> Literal[42]:
+    """
+    Run a placeholder function.
+
+    Examples
+    --------
+    >>> placeholder()
+    42
+    """
+    return 42
diff --git a/uv.lock b/uv.lock
index 6a272d9..e5b7c86 100644
--- a/uv.lock
+++ b/uv.lock
@@ -1094,11 +1094,16 @@ dev = [
     { name = "pytest" },
     { name = "pytest-filter-subpackage" },
     { name = "pytest-xdist" },
+    { name = "sphinx" },
+    { name = "sphinx-copybutton" },
+    { name = "sphinx-notfound-page" },
     { name = "ty" },
     { name = "zizmor" },
 ]
 docs = [
     { name = "sphinx" },
+    { name = "sphinx-copybutton" },
+    { name = "sphinx-notfound-page" },
 ]
 lint = [
     { name = "pre-commit" },
@@ -1133,10 +1138,17 @@ dev = [
     { name = "pytest", specifier = ">=9.1" },
     { name = "pytest-filter-subpackage", specifier = ">=0.2" },
     { name = "pytest-xdist", specifier = ">=3.8" },
+    { name = "sphinx", specifier = ">=9.1" },
+    { name = "sphinx-copybutton", specifier = ">=0.5.2" },
+    { name = "sphinx-notfound-page", specifier = ">=1.1" },
     { name = "ty", specifier = ">=0.0.74" },
     { name = "zizmor", specifier = ">=1.29" },
 ]
-docs = [{ name = "sphinx", specifier = ">=9.1.0" }]
+docs = [
+    { name = "sphinx", specifier = ">=9.1" },
+    { name = "sphinx-copybutton", specifier = ">=0.5.2" },
+    { name = "sphinx-notfound-page", specifier = ">=1.1" },
+]
 lint = [{ name = "pre-commit", specifier = ">=4.6.2" }]
 nox = [
     { name = "nox", specifier = ">=2026.8.10" },
@@ -1421,6 +1433,30 @@ wheels = [
     { url = "https://files.pythonhosted.org/packages/73/f7/b1884cb3188ab181fc81fa00c266699dab600f927a964df02ec3d5d1916a/sphinx-9.1.0-py3-none-any.whl", hash = "sha256:c84fdd4e782504495fe4f2c0b3413d6c2bf388589bb352d439b2a3bb99991978", size = 3921742, upload-time = "2025-12-31T15:09:25.561Z" },
 ]
 
+[[package]]
+name = "sphinx-copybutton"
+version = "0.5.2"
+source = { registry = "https://pypi.org/simple" }
+dependencies = [
+    { name = "sphinx" },
+]
+sdist = { url = "https://files.pythonhosted.org/packages/fc/2b/a964715e7f5295f77509e59309959f4125122d648f86b4fe7d70ca1d882c/sphinx-copybutton-0.5.2.tar.gz", hash = "sha256:4cf17c82fb9646d1bc9ca92ac280813a3b605d8c421225fd9913154103ee1fbd", size = 23039, upload-time = "2023-04-14T08:10:22.998Z" }
+wheels = [
+    { url = "https://files.pythonhosted.org/packages/9e/48/1ea60e74949eecb12cdd6ac43987f9fd331156388dcc2319b45e2ebb81bf/sphinx_copybutton-0.5.2-py3-none-any.whl", hash = "sha256:fb543fd386d917746c9a2c50360c7905b605726b9355cd26e9974857afeae06e", size = 13343, upload-time = "2023-04-14T08:10:20.844Z" },
+]
+
+[[package]]
+name = "sphinx-notfound-page"
+version = "1.1.0"
+source = { registry = "https://pypi.org/simple" }
+dependencies = [
+    { name = "sphinx" },
+]
+sdist = { url = "https://files.pythonhosted.org/packages/6a/b2/67603444a8ee97b4a8ea71b0a9d6bab1727ed65e362c87e02f818ee57b8a/sphinx_notfound_page-1.1.0.tar.gz", hash = "sha256:913e1754370bb3db201d9300d458a8b8b5fb22e9246a816643a819a9ea2b8067", size = 7392, upload-time = "2025-01-28T18:45:02.871Z" }
+wheels = [
+    { url = "https://files.pythonhosted.org/packages/cd/d4/019fe439c840a7966012bbb95ccbdd81c5c10271749706793b43beb05145/sphinx_notfound_page-1.1.0-py3-none-any.whl", hash = "sha256:835dc76ff7914577a1f58d80a2c8418fb6138c0932c8da8adce4d9096fbcd389", size = 8167, upload-time = "2025-01-28T18:45:00.465Z" },
+]
+
 [[package]]
 name = "sphinxcontrib-applehelp"
 version = "2.0.0"