diff --git a/.gitignore b/.gitignore
index 9efceef63..ceafd9946 100644
--- a/.gitignore
+++ b/.gitignore
@@ -41,3 +41,4 @@ TODO
 /scripts/testbrowser/cpp/webengine/.qmake.stash
 /scripts/dev/pylint_checkers/qute_pylint.egg-info
 /misc/file_version_info.txt
+/doc/extapi/_build
diff --git a/doc/extapi/_static/.gitkeep b/doc/extapi/_static/.gitkeep
new file mode 100644
index 000000000..e69de29bb
diff --git a/doc/extapi/_templates/.gitkeep b/doc/extapi/_templates/.gitkeep
new file mode 100644
index 000000000..e69de29bb
diff --git a/doc/extapi/api.rst b/doc/extapi/api.rst
new file mode 100644
index 000000000..b63db57c3
--- /dev/null
+++ b/doc/extapi/api.rst
@@ -0,0 +1,48 @@
+API modules
+===========
+
+cmdutils module
+---------------
+
+.. automodule:: qutebrowser.api.cmdutils
+   :members:
+   :imported-members:
+
+apitypes module
+---------------
+
+.. automodule:: qutebrowser.api.apitypes
+   :members:
+   :imported-members:
+
+config module
+-------------
+
+.. automodule:: qutebrowser.api.config
+   :members:
+
+downloads module
+----------------
+
+.. automodule:: qutebrowser.api.downloads
+   :members:
+
+hook module
+-----------
+
+.. automodule:: qutebrowser.api.hook
+   :members:
+
+interceptor module
+------------------
+
+.. automodule:: qutebrowser.api.interceptor
+   :members:
+   :imported-members:
+
+message module
+--------------
+
+.. automodule:: qutebrowser.api.message
+   :members:
+   :imported-members:
diff --git a/doc/extapi/conf.py b/doc/extapi/conf.py
new file mode 100644
index 000000000..4cc5c6803
--- /dev/null
+++ b/doc/extapi/conf.py
@@ -0,0 +1,179 @@
+# -*- coding: utf-8 -*-
+#
+# Configuration file for the Sphinx documentation builder.
+#
+# This file does only contain a selection of the most common options. For a
+# full list see the documentation:
+# http://www.sphinx-doc.org/en/master/config
+
+# -- Path setup --------------------------------------------------------------
+
+# If extensions (or modules to document with autodoc) are in another directory,
+# add these directories to sys.path here. If the directory is relative to the
+# documentation root, use os.path.abspath to make it absolute, like shown here.
+#
+# import os
+# import sys
+# sys.path.insert(0, os.path.abspath('.'))
+
+
+# -- Project information -----------------------------------------------------
+
+project = 'qutebrowser extensions'
+copyright = '2018, Florian Bruhin'
+author = 'Florian Bruhin'
+
+# The short X.Y version
+version = ''
+# The full version, including alpha/beta/rc tags
+release = ''
+
+
+# -- General configuration ---------------------------------------------------
+
+# If your documentation needs a minimal Sphinx version, state it here.
+#
+# needs_sphinx = '1.0'
+
+# Add any Sphinx extension module names here, as strings. They can be
+# extensions coming with Sphinx (named 'sphinx.ext.*') or your custom
+# ones.
+extensions = [
+    'sphinx.ext.autodoc',
+    'sphinx.ext.napoleon',
+]
+autodoc_member_order = 'bysource'
+
+# Add any paths that contain templates here, relative to this directory.
+templates_path = ['_templates']
+
+# The suffix(es) of source filenames.
+# You can specify multiple suffix as a list of string:
+#
+# source_suffix = ['.rst', '.md']
+source_suffix = '.rst'
+
+# The master toctree document.
+master_doc = 'index'
+
+# The language for content autogenerated by Sphinx. Refer to documentation
+# for a list of supported languages.
+#
+# This is also used if you do content translation via gettext catalogs.
+# Usually you set "language" from the command line for these cases.
+language = None
+
+# List of patterns, relative to source directory, that match files and
+# directories to ignore when looking for source files.
+# This pattern also affects html_static_path and html_extra_path.
+exclude_patterns = ['_build', 'Thumbs.db', '.DS_Store']
+
+# The name of the Pygments (syntax highlighting) style to use.
+pygments_style = None
+
+
+# -- Options for HTML output -------------------------------------------------
+
+# The theme to use for HTML and HTML Help pages.  See the documentation for
+# a list of builtin themes.
+#
+html_theme = 'alabaster'
+
+# Theme options are theme-specific and customize the look and feel of a theme
+# further.  For a list of options available for each theme, see the
+# documentation.
+#
+# html_theme_options = {}
+
+# Add any paths that contain custom static files (such as style sheets) here,
+# relative to this directory. They are copied after the builtin static files,
+# so a file named "default.css" will overwrite the builtin "default.css".
+html_static_path = ['_static']
+
+# Custom sidebar templates, must be a dictionary that maps document names
+# to template names.
+#
+# The default sidebars (for documents that don't match any pattern) are
+# defined by theme itself.  Builtin themes are using these templates by
+# default: ``['localtoc.html', 'relations.html', 'sourcelink.html',
+# 'searchbox.html']``.
+#
+# html_sidebars = {}
+
+
+# -- Options for HTMLHelp output ---------------------------------------------
+
+# Output file base name for HTML help builder.
+htmlhelp_basename = 'qutebrowserextensionsdoc'
+
+
+# -- Options for LaTeX output ------------------------------------------------
+
+latex_elements = {
+    # The paper size ('letterpaper' or 'a4paper').
+    #
+    # 'papersize': 'letterpaper',
+
+    # The font size ('10pt', '11pt' or '12pt').
+    #
+    # 'pointsize': '10pt',
+
+    # Additional stuff for the LaTeX preamble.
+    #
+    # 'preamble': '',
+
+    # Latex figure (float) alignment
+    #
+    # 'figure_align': 'htbp',
+}
+
+# Grouping the document tree into LaTeX files. List of tuples
+# (source start file, target name, title,
+#  author, documentclass [howto, manual, or own class]).
+latex_documents = [
+    (master_doc, 'qutebrowserextensions.tex', 'qutebrowser extensions Documentation',
+     'Florian Bruhin', 'manual'),
+]
+
+
+# -- Options for manual page output ------------------------------------------
+
+# One entry per manual page. List of tuples
+# (source start file, name, description, authors, manual section).
+man_pages = [
+    (master_doc, 'qutebrowserextensions', 'qutebrowser extensions Documentation',
+     [author], 1)
+]
+
+
+# -- Options for Texinfo output ----------------------------------------------
+
+# Grouping the document tree into Texinfo files. List of tuples
+# (source start file, target name, title, author,
+#  dir menu entry, description, category)
+texinfo_documents = [
+    (master_doc, 'qutebrowserextensions', 'qutebrowser extensions Documentation',
+     author, 'qutebrowserextensions', 'One line description of project.',
+     'Miscellaneous'),
+]
+
+
+# -- Options for Epub output -------------------------------------------------
+
+# Bibliographic Dublin Core info.
+epub_title = project
+
+# The unique identifier of the text. This can be a ISBN number
+# or the project homepage.
+#
+# epub_identifier = ''
+
+# A unique identification for the text.
+#
+# epub_uid = ''
+
+# A list of files that should not be packed into the epub file.
+epub_exclude_files = ['search.html']
+
+
+# -- Extension configuration -------------------------------------------------
diff --git a/doc/extapi/index.rst b/doc/extapi/index.rst
new file mode 100644
index 000000000..d181c2ccd
--- /dev/null
+++ b/doc/extapi/index.rst
@@ -0,0 +1,22 @@
+.. qutebrowser extensions documentation master file, created by
+   sphinx-quickstart on Tue Dec 11 18:59:44 2018.
+   You can adapt this file completely to your liking, but it should at least
+   contain the root `toctree` directive.
+
+Welcome to qutebrowser extensions's documentation!
+==================================================
+
+.. toctree::
+   :maxdepth: 2
+   :caption: Contents:
+
+   api
+   tab
+
+
+Indices and tables
+==================
+
+* :ref:`genindex`
+* :ref:`modindex`
+* :ref:`search`
diff --git a/doc/extapi/tab.rst b/doc/extapi/tab.rst
new file mode 100644
index 000000000..57a14ac6e
--- /dev/null
+++ b/doc/extapi/tab.rst
@@ -0,0 +1,44 @@
+Tab API
+=======
+
+.. autoclass:: qutebrowser.browser.browsertab.AbstractTab()
+   :members:
+
+.. autoclass:: qutebrowser.browser.browsertab.AbstractAction()
+   :members:
+
+.. autoclass:: qutebrowser.browser.browsertab.AbstractPrinting()
+   :members:
+
+.. autoclass:: qutebrowser.browser.browsertab.AbstractSearch()
+   :members:
+
+.. autoclass:: qutebrowser.browser.browsertab.AbstractZoom()
+   :members:
+
+.. autoclass:: qutebrowser.browser.browsertab.AbstractCaret()
+   :members:
+
+.. autoclass:: qutebrowser.browser.browsertab.AbstractScroller()
+   :members:
+
+.. autoclass:: qutebrowser.browser.browsertab.AbstractHistory()
+   :members:
+
+.. autoclass:: qutebrowser.browser.browsertab.AbstractElements()
+   :members:
+
+.. autoclass:: qutebrowser.browser.browsertab.AbstractAudio()
+   :members:
+
+Web element API
+===============
+
+.. autoclass:: qutebrowser.browser.webelem.AbstractWebElement
+   :members:
+
+.. autoclass:: qutebrowser.browser.webelem.Error
+   :members:
+
+.. autoclass:: qutebrowser.browser.webelem.OrphanedError
+   :members:
diff --git a/misc/requirements/requirements-sphinx.txt b/misc/requirements/requirements-sphinx.txt
new file mode 100644
index 000000000..c0801a48e
--- /dev/null
+++ b/misc/requirements/requirements-sphinx.txt
@@ -0,0 +1,21 @@
+# This file is automatically generated by scripts/dev/recompile_requirements.py
+
+alabaster==0.7.12
+Babel==2.6.0
+certifi==2018.11.29
+chardet==3.0.4
+docutils==0.14
+idna==2.8
+imagesize==1.1.0
+Jinja2==2.10
+MarkupSafe==1.1.0
+packaging==18.0
+Pygments==2.3.0
+pyparsing==2.3.0
+pytz==2018.7
+requests==2.21.0
+six==1.12.0
+snowballstemmer==1.2.1
+Sphinx==1.8.2
+sphinxcontrib-websupport==1.1.0
+urllib3==1.24.1
diff --git a/misc/requirements/requirements-sphinx.txt-raw b/misc/requirements/requirements-sphinx.txt-raw
new file mode 100644
index 000000000..6966869c7
--- /dev/null
+++ b/misc/requirements/requirements-sphinx.txt-raw
@@ -0,0 +1 @@
+sphinx
diff --git a/qutebrowser/api/cmdutils.py b/qutebrowser/api/cmdutils.py
index 093244727..f6a6f6da9 100644
--- a/qutebrowser/api/cmdutils.py
+++ b/qutebrowser/api/cmdutils.py
@@ -17,7 +17,38 @@
 # You should have received a copy of the GNU General Public License
 # along with qutebrowser.  If not, see <http://www.gnu.org/licenses/>.
 
-"""Utilities for command handlers."""
+"""
+qutebrowser has the concept of functions which are exposed to the user as
+commands.
+
+Creating a new command is straightforward::
+
+  from qutebrowser.api import cmdutils
+
+  @cmdutils.register(...)
+  def foo():
+      ...
+
+The commands arguments are automatically deduced by inspecting your function.
+
+The types of the function arguments are inferred based on their default values,
+e.g., an argument `foo=True` will be converted to a flag `-f`/`--foo` in
+qutebrowser's commandline.
+
+The type can be overridden using Python's function annotations::
+
+  @cmdutils.register(...)
+  def foo(bar: int, baz=True):
+      ...
+
+Possible values:
+
+- A callable (``int``, ``float``, etc.): Gets called to validate/convert the value.
+- A python enum type: All members of the enum are possible values.
+- A ``typing.Union`` of multiple types above: Any of these types are valid
+  values, e.g., ``typing.Union[str, int]``.
+"""
+
 
 import inspect
 import typing
@@ -33,15 +64,17 @@ class CommandError(cmdexc.Error):
     """Raised when a command encounters an error while running.
 
     If your command handler encounters an error and cannot continue, raise this
-    exception with an appropriate error message:
+    exception with an appropriate error message::
 
         raise cmdexc.CommandError("Message")
 
     The message will then be shown in the qutebrowser status bar.
 
-    Note that you should only raise this exception while a command handler is
-    run. Raising it at another point causes qutebrowser to crash due to an
-    unhandled exception.
+    .. note::
+
+       You should only raise this exception while a command handler is run.
+       Raising it at another point causes qutebrowser to crash due to an
+       unhandled exception.
     """
 
 
@@ -76,13 +109,7 @@ def check_exclusive(flags: typing.Iterable[bool],
 
 class register:  # noqa: N801,N806 pylint: disable=invalid-name
 
-    """Decorator to register a new command handler.
-
-    Attributes:
-        _instance: The object from the object registry to be used as "self".
-        _name: The name (as string) or names (as list) of the command.
-        _kwargs: The arguments to pass to Command.
-    """
+    """Decorator to register a new command handler."""
 
     def __init__(self, *,
                  instance: str = None,
@@ -95,8 +122,11 @@ class register:  # noqa: N801,N806 pylint: disable=invalid-name
         Args:
             See class attributes.
         """
+        # The object from the object registry to be used as "self".
         self._instance = instance
+        # The name (as string) or names (as list) of the command.
         self._name = name
+        # The arguments to pass to Command.
         self._kwargs = kwargs
 
     def __call__(self, func: typing.Callable) -> typing.Callable:
@@ -127,16 +157,47 @@ class register:  # noqa: N801,N806 pylint: disable=invalid-name
 
 class argument:  # noqa: N801,N806 pylint: disable=invalid-name
 
-    """Decorator to customize an argument for @cmdutils.register.
+    """Decorator to customize an argument.
 
-    Attributes:
-        _argname: The name of the argument to handle.
-        _kwargs: Keyword arguments, valid ArgInfo members
+    You can customize how an argument is handled using the ``@cmdutils.argument``
+    decorator *after* ``@cmdutils.register``. This can, for example, be used to
+    customize the flag an argument should get::
+
+      @cmdutils.register(...)
+      @cmdutils.argument('bar', flag='c')
+      def foo(bar):
+          ...
+
+    For a ``str`` argument, you can restrict the allowed strings using ``choices``::
+
+      @cmdutils.register(...)
+      @cmdutils.argument('bar', choices=['val1', 'val2'])
+      def foo(bar: str):
+          ...
+
+    For ``typing.Union`` types, the given ``choices`` are only checked if other types
+    (like ``int``) don't match.
+
+    The following arguments are supported for ``@cmdutils.argument``:
+
+    - ``flag``: Customize the short flag (``-x``) the argument will get.
+    - ``value``: Tell qutebrowser to fill the argument with special values:
+
+      * ``value=cmdutils.Value.count``: The ``count`` given by the user to the command.
+      * ``value=cmdutils.Value.win_id``: The window ID of the current window.
+      * ``value=cmdutils.Value.cur_tab``: The tab object which is currently focused.
+
+    - ``completion``: A completion function to use when completing arguments for
+      the given command.
+    - ``choices``: The allowed string choices for the argument.
+
+    The name of an argument will always be the parameter name, with any trailing
+    underscores stripped and underscores replaced by dashes.
     """
 
     def __init__(self, argname: str, **kwargs: typing.Any) -> None:
-        self._argname = argname
-        self._kwargs = kwargs
+        self._argname = argname   # The name of the argument to handle.
+        self._kwargs = kwargs  # Valid ArgInfo members.
 
     def __call__(self, func: typing.Callable) -> typing.Callable:
         funcname = func.__name__
diff --git a/qutebrowser/api/config.py b/qutebrowser/api/config.py
index 4a5d73936..0c633e54d 100644
--- a/qutebrowser/api/config.py
+++ b/qutebrowser/api/config.py
@@ -25,6 +25,16 @@ from PyQt5.QtCore import QUrl
 
 from qutebrowser.config import config
 
+#: Simplified access to config values using attribute acccess.
+#: For example, to access the ``content.javascript.enabled`` setting,
+#: you can do::
+#:
+#:   if config.val.content.javascript.enabled:
+#:       ...
+#:
+#: This also supports setting configuration values::
+#:
+#:   config.val.content.javascript.enabled = False
 val = typing.cast('config.ConfigContainer', None)
 
 
diff --git a/qutebrowser/api/downloads.py b/qutebrowser/api/downloads.py
index 82c68d0bd..a2a37d931 100644
--- a/qutebrowser/api/downloads.py
+++ b/qutebrowser/api/downloads.py
@@ -52,6 +52,21 @@ def download_temp(url: QUrl) -> TempDownload:
     """Download the given URL into a file object.
 
     The download is not saved to disk.
+
+    Returns a ``TempDownload`` object, which triggers a ``finished`` signal
+    when the download has finished::
+
+        dl = downloads.download_temp(QUrl("https://www.example.com/"))
+        dl.finished.connect(functools.partial(on_download_finished, dl))
+
+    After the download has finished, its ``successful`` attribute can be
+    checked to make sure it finished successfully. If so, its contents can be
+    read by accessing the ``fileobj`` attribute::
+
+        def on_download_finished(download: downloads.TempDownload) -> None:
+            if download.successful:
+                print(download.fileobj.read())
+                download.fileobj.close()
     """
     fobj = io.BytesIO()
     fobj.name = 'temporary: ' + url.host()
diff --git a/qutebrowser/api/hook.py b/qutebrowser/api/hook.py
index 3f06121da..84e103cbd 100644
--- a/qutebrowser/api/hook.py
+++ b/qutebrowser/api/hook.py
@@ -36,7 +36,17 @@ def _add_module_info(func: typing.Callable) -> loader.ModuleInfo:
 
 class init:
 
-    """Decorator to mark a function to run when initializing."""
+    """Decorator to mark a function to run when initializing.
+
+    The decorated function gets called with a
+    :class:`qutebrowser.api.apitypes.InitContext` as argument.
+
+    Example::
+
+        @hook.init()
+        def init(_context):
+            message.info("Extension initialized.")
+    """
 
     def __call__(self, func: typing.Callable) -> typing.Callable:
         info = _add_module_info(func)
@@ -48,7 +58,30 @@ class init:
 
 class config_changed:
 
-    """Decorator to get notified about changed configs."""
+    """Decorator to get notified about changed configs.
+
+    By default, the decorated function is called when any change in the config
+    occurs::
+
+        @hook.config_changed()
+        def on_config_changed():
+            ...
+
+    When an option name is passed, it's only called when the given option was
+    changed::
+
+        @hook.config_changed('content.javascript.enabled')
+        def on_config_changed():
+            ...
+
+    Alternatively, a part of an option name can be specified. In the following
+    snippet, ``on_config_changed`` gets called when either
+    ``bindings.commands`` or ``bindings.key_mappings`` have changed::
+
+        @hook.config_changed('bindings')
+        def on_config_changed():
+            ...
+    """
 
     def __init__(self, option_filter: str = None) -> None:
         self._filter = option_filter
diff --git a/qutebrowser/api/interceptor.py b/qutebrowser/api/interceptor.py
index a40635fca..634ae1409 100644
--- a/qutebrowser/api/interceptor.py
+++ b/qutebrowser/api/interceptor.py
@@ -27,7 +27,13 @@ from qutebrowser.extensions.interceptors import Request
 def register(interceptor: interceptors.InterceptorType) -> None:
     """Register a request interceptor.
 
-    Whenever a request happens, the interceptor gets called with a Request
-    object.
+    Whenever a request happens, the interceptor gets called with a
+    :class:`Request` object.
+
+    Example::
+
+        def intercept(request: interceptor.Request) -> None:
+            if request.request_url.host() == 'badhost.example.com':
+                request.block()
     """
     interceptors.register(interceptor)
diff --git a/qutebrowser/browser/browsertab.py b/qutebrowser/browser/browsertab.py
index 3bd4c55c3..029394657 100644
--- a/qutebrowser/browser/browsertab.py
+++ b/qutebrowser/browser/browsertab.py
@@ -141,14 +141,11 @@ class TabData:
 
 class AbstractAction:
 
-    """Attribute of AbstractTab for Qt WebActions.
-
-    Class attributes (overridden by subclasses):
-        action_class: The class actions are defined on (QWeb{Engine,}Page)
-        action_base: The type of the actions (QWeb{Engine,}Page.WebAction)
-    """
+    """Attribute ``action`` of AbstractTab for Qt WebActions."""
 
+    # The class actions are defined on (QWeb{Engine,}Page)
     action_class = None  # type: type
+    # The type of the actions (QWeb{Engine,}Page.WebAction)
     action_base = None  # type: type
 
     def __init__(self, tab: 'AbstractTab') -> None:
@@ -200,7 +197,7 @@ class AbstractAction:
 
 class AbstractPrinting:
 
-    """Attribute of AbstractTab for printing the page."""
+    """Attribute ``printing`` of AbstractTab for printing the page."""
 
     def __init__(self, tab: 'AbstractTab') -> None:
         self._widget = None
@@ -271,7 +268,7 @@ class AbstractPrinting:
 
 class AbstractSearch(QObject):
 
-    """Attribute of AbstractTab for doing searches.
+    """Attribute ``search`` of AbstractTab for doing searches.
 
     Attributes:
         text: The last thing this view was searched for.
@@ -279,15 +276,14 @@ class AbstractSearch(QObject):
                           this view.
         _flags: The flags of the last search (needs to be set by subclasses).
         _widget: The underlying WebView widget.
-
-    Signals:
-        finished: Emitted when a search was finished.
-                  arg: True if the text was found, False otherwise.
-        cleared: Emitted when an existing search was cleared.
     """
 
+    #: Signal emitted when a search was finished
+    #: (True if the text was found, False otherwise)
     finished = pyqtSignal(bool)
+    #: Signal emitted when an existing search was cleared.
     cleared = pyqtSignal()
+
     _Callback = typing.Callable[[bool], None]
 
     def __init__(self, tab: 'AbstractTab', parent: QWidget = None):
@@ -350,17 +346,13 @@ class AbstractSearch(QObject):
 
 class AbstractZoom(QObject):
 
-    """Attribute of AbstractTab for controlling zoom.
-
-    Attributes:
-        _neighborlist: A NeighborList with the zoom levels.
-        _default_zoom_changed: Whether the zoom was changed from the default.
-    """
+    """Attribute ``zoom`` of AbstractTab for controlling zoom."""
 
     def __init__(self, tab: 'AbstractTab', parent: QWidget = None) -> None:
         super().__init__(parent)
         self._tab = tab
         self._widget = None
+        # Whether zoom was changed from the default.
         self._default_zoom_changed = False
         self._init_neighborlist()
         config.instance.changed.connect(self._on_config_changed)
@@ -375,7 +367,9 @@ class AbstractZoom(QObject):
             self._init_neighborlist()
 
     def _init_neighborlist(self) -> None:
-        """Initialize self._neighborlist."""
+        """Initialize self._neighborlist.
+
+        It is a NeighborList with the zoom levels."""
         levels = config.val.zoom.levels
         self._neighborlist = usertypes.NeighborList(
             levels, mode=usertypes.NeighborList.Modes.edge)
@@ -427,15 +421,12 @@ class AbstractZoom(QObject):
 
 class AbstractCaret(QObject):
 
-    """Attribute of AbstractTab for caret browsing.
-
-    Signals:
-        selection_toggled: Emitted when the selection was toggled.
-                           arg: Whether the selection is now active.
-        follow_selected_done: Emitted when a follow_selection action is done.
-    """
+    """Attribute ``caret`` of AbstractTab for caret browsing."""
 
+    #: Signal emitted when the selection was toggled.
+    #: (argument - whether the selection is now active)
     selection_toggled = pyqtSignal(bool)
+    #: Emitted when a ``follow_selection`` action is done.
     follow_selected_done = pyqtSignal()
 
     def __init__(self,
@@ -522,16 +513,12 @@ class AbstractCaret(QObject):
 
 class AbstractScroller(QObject):
 
-    """Attribute of AbstractTab to manage scroll position.
-
-    Signals:
-        perc_changed: The scroll position changed.
-        before_jump_requested:
-            Emitted by other code when the user requested a jump.
-            Used to set the special ' mark so the user can return.
-    """
+    """Attribute ``scroller`` of AbstractTab to manage scroll position."""
 
+    #: Signal emitted when the scroll position changed (int, int)
     perc_changed = pyqtSignal(int, int)
+    #: Signal emitted before the user requested a jump.
+    #: Used to set the special ' mark so the user can return.
     before_jump_requested = pyqtSignal()
 
     def __init__(self, tab: 'AbstractTab', parent: QWidget = None):
@@ -833,42 +820,46 @@ class AbstractTabPrivate:
 
 class AbstractTab(QWidget):
 
-    """An adapter for QWebView/QWebEngineView representing a single tab.
-
-    Signals:
-        See related Qt signals.
-
-        new_tab_requested: Emitted when a new tab should be opened with the
-                           given URL.
-        load_status_changed: The loading status changed
-        fullscreen_requested: Fullscreen display was requested by the page.
-                              arg: True if fullscreen should be turned on,
-                                   False if it should be turned off.
-        renderer_process_terminated: Emitted when the underlying renderer
-                                     process terminated.
-                                     arg 0: A TerminationStatus member.
-                                     arg 1: The exit code.
-        before_load_started: Emitted before we tell Qt to open a URL.
-    """
+    """An adapter for QWebView/QWebEngineView representing a single tab."""
 
+    #: Signal emitted when a website requests to close this tab.
     window_close_requested = pyqtSignal()
+    #: Signal emitted when a link is hovered (the hover text)
     link_hovered = pyqtSignal(str)
+    #: Signal emitted when a page started loading
     load_started = pyqtSignal()
+    #: Signal emitted when a page is loading (progress percentage)
     load_progress = pyqtSignal(int)
+    #: Signal emitted when a page finished loading (success as bool)
     load_finished = pyqtSignal(bool)
+    #: Signal emitted when a page's favicon changed (icon as QIcon)
     icon_changed = pyqtSignal(QIcon)
+    #: Signal emitted when a page's title changed (new title as str)
     title_changed = pyqtSignal(str)
-    load_status_changed = pyqtSignal(usertypes.LoadStatus)
+    #: Signal emitted when a new tab should be opened (url as QUrl)
     new_tab_requested = pyqtSignal(QUrl)
+    #: Signal emitted when a page's URL changed (url as QUrl)
     url_changed = pyqtSignal(QUrl)
-    shutting_down = pyqtSignal()
+    #: Signal emitted when a tab's content size changed
+    #: (new size as QSizeF)
     contents_size_changed = pyqtSignal(QSizeF)
-    # url, requested url, title
-    history_item_triggered = pyqtSignal(QUrl, QUrl, str)
+    #: Signal emitted when a page requested full-screen (bool)
     fullscreen_requested = pyqtSignal(bool)
-    renderer_process_terminated = pyqtSignal(TerminationStatus, int)
+    #: Signal emitted before load starts (URL as QUrl)
     before_load_started = pyqtSignal(QUrl)
 
+    # Signal emitted when a page's load status changed
+    # (argument: usertypes.LoadStatus)
+    load_status_changed = pyqtSignal(usertypes.LoadStatus)
+    # Signal emitted before shutting down
+    shutting_down = pyqtSignal()
+    # Signal emitted when a history item should be added
+    history_item_triggered = pyqtSignal(QUrl, QUrl, str)
+    # Signal emitted when the underlying renderer process terminated.
+    # arg 0: A TerminationStatus member.
+    # arg 1: The exit code.
+    renderer_process_terminated = pyqtSignal(TerminationStatus, int)
+
     def __init__(self, *, win_id: int, private: bool,
                  parent: QWidget = None) -> None:
         self.is_private = private
diff --git a/qutebrowser/browser/webelem.py b/qutebrowser/browser/webelem.py
index a22facfbd..c00f247f6 100644
--- a/qutebrowser/browser/webelem.py
+++ b/qutebrowser/browser/webelem.py
@@ -141,20 +141,9 @@ class AbstractWebElement(collections.abc.MutableMapping):
     def rect_on_view(self, *, elem_geometry=None, no_js=False):
         """Get the geometry of the element relative to the webview.
 
-        Uses the getClientRects() JavaScript method to obtain the collection of
-        rectangles containing the element and returns the first rectangle which
-        is large enough (larger than 1px times 1px). If all rectangles returned
-        by getClientRects() are too small, falls back to elem.rect_on_view().
-
-        Skipping of small rectangles is due to <a> elements containing other
-        elements with "display:block" style, see
-        https://github.com/qutebrowser/qutebrowser/issues/1298
-
         Args:
             elem_geometry: The geometry of the element, or None.
-                           Calling QWebElement::geometry is rather expensive so
-                           we want to avoid doing it twice.
-            no_js: Fall back to the Python implementation
+            no_js: Fall back to the Python implementation.
         """
         raise NotImplementedError
 
diff --git a/qutebrowser/extensions/interceptors.py b/qutebrowser/extensions/interceptors.py
index 4a3ac17d4..269c82ab8 100644
--- a/qutebrowser/extensions/interceptors.py
+++ b/qutebrowser/extensions/interceptors.py
@@ -34,8 +34,12 @@ class Request:
 
     """A request which can be intercepted/blocked."""
 
+    #: The URL of the page being shown.
     first_party_url = attr.ib()  # type: QUrl
+
+    #: The URL of the file being requested.
     request_url = attr.ib()  # type: QUrl
+
     is_blocked = attr.ib(False)  # type: bool
 
     def block(self) -> None:
diff --git a/qutebrowser/utils/message.py b/qutebrowser/utils/message.py
index b496273f8..6731721aa 100644
--- a/qutebrowser/utils/message.py
+++ b/qutebrowser/utils/message.py
@@ -42,12 +42,12 @@ def _log_stack(typ: str, stack: str) -> None:
 
 
 def error(message: str, *, stack: str = None, replace: bool = False) -> None:
-    """Convenience function to display an error message in the statusbar.
+    """Display an error message.
 
     Args:
-        message: The message to show
-        stack: The stack trace to show.
-        replace: Replace existing messages with replace=True
+        message: The message to show.
+        stack: The stack trace to show (if any).
+        replace: Replace existing messages which are still being shown.
     """
     if stack is None:
         stack = ''.join(traceback.format_stack())
@@ -60,11 +60,11 @@ def error(message: str, *, stack: str = None, replace: bool = False) -> None:
 
 
 def warning(message: str, *, replace: bool = False) -> None:
-    """Convenience function to display a warning message in the statusbar.
+    """Display a warning message.
 
     Args:
-        message: The message to show
-        replace: Replace existing messages with replace=True
+        message: The message to show.
+        replace: Replace existing messages which are still being shown.
     """
     _log_stack('warning', ''.join(traceback.format_stack()))
     log.message.warning(message)
@@ -72,11 +72,11 @@ def warning(message: str, *, replace: bool = False) -> None:
 
 
 def info(message: str, *, replace: bool = False) -> None:
-    """Convenience function to display an info message in the statusbar.
+    """Display an info message.
 
     Args:
-        message: The message to show
-        replace: Replace existing messages with replace=True
+        message: The message to show.
+        replace: Replace existing messages which are still being shown.
     """
     log.message.info(message)
     global_bridge.show(usertypes.MessageLevel.info, message, replace)
diff --git a/qutebrowser/utils/usertypes.py b/qutebrowser/utils/usertypes.py
index c948df48f..84b7e7f9b 100644
--- a/qutebrowser/utils/usertypes.py
+++ b/qutebrowser/utils/usertypes.py
@@ -210,15 +210,33 @@ PromptMode = enum.Enum('PromptMode', ['yesno', 'text', 'user_pwd', 'alert',
                                       'download'])
 
 
-# Where to open a clicked link.
-ClickTarget = enum.Enum('ClickTarget', ['normal', 'tab', 'tab_bg', 'window',
-                                        'hover'])
+class ClickTarget(enum.Enum):
+
+    """How to open a clicked link."""
+
+    normal = 0  #: Open the link in the current tab
+    tab = 1  #: Open the link in a new foreground tab
+    tab_bg = 2  #: Open the link in a new background tab
+    window = 3  #: Open the link in a new window
+    hover = 4  #: Only hover over the link
 
 
-# Key input modes
-KeyMode = enum.Enum('KeyMode', ['normal', 'hint', 'command', 'yesno', 'prompt',
-                                'insert', 'passthrough', 'caret', 'set_mark',
-                                'jump_mark', 'record_macro', 'run_macro'])
+class KeyMode(enum.Enum):
+
+    """Key input modes."""
+
+    normal = 1  #: Normal mode (no mode was entered)
+    hint = 2  #: Hint mode (showing labels for links)
+    command = 3  #: Command mode (after pressing the colon key)
+    yesno = 4  #: Yes/No prompts
+    prompt = 5  #: Text prompts
+    insert = 6  #: Insert mode (passing through most keys)
+    passthrough = 7  #: Passthrough mode (passing through all keys)
+    caret = 8  #: Caret mode (moving cursor with keys)
+    set_mark = 9
+    jump_mark = 10
+    record_macro = 11
+    run_macro = 12
 
 
 class Exit(enum.IntEnum):
@@ -241,8 +259,14 @@ LoadStatus = enum.Enum('LoadStatus', ['none', 'success', 'success_https',
 Backend = enum.Enum('Backend', ['QtWebKit', 'QtWebEngine'])
 
 
-# JS world for QtWebEngine
-JsWorld = enum.Enum('JsWorld', ['main', 'application', 'user', 'jseval'])
+class JsWorld(enum.Enum):
+
+    """World/context to run JavaScript code in."""
+
+    main = 1  #: Same world as the web page's JavaScript.
+    application = 2  #: Application world, used by qutebrowser internally.
+    user = 3  #: User world, currently not used.
+    jseval = 4  #: World used for the jseval-command.
 
 
 # Log level of a JS message. This needs to match up with the keys allowed for
diff --git a/tox.ini b/tox.ini
index 8a4232aaa..bc44df987 100644
--- a/tox.ini
+++ b/tox.ini
@@ -199,3 +199,14 @@ deps =
     -r{toxinidir}/misc/requirements/requirements-mypy.txt
 commands =
     {envpython} -m mypy qutebrowser {posargs}
+
+[testenv:sphinx]
+basepython = {env:PYTHON:python3}
+passenv =
+usedevelop = true
+deps =
+    -r{toxinidir}/requirements.txt
+    -r{toxinidir}/misc/requirements/requirements-pyqt.txt
+    -r{toxinidir}/misc/requirements/requirements-sphinx.txt
+commands =
+    {envpython} -m sphinx -jauto -W --color {posargs} doc/extapi/ doc/extapi/_build/