diff --git a/datasette/app.py b/datasette/app.py
index 773dee31..37b4ed3d 100644
--- a/datasette/app.py
+++ b/datasette/app.py
@@ -586,6 +586,9 @@ class Datasette:
             )
         return d
 
+    def _actor(self, request):
+        return {"actor": request.scope.get("actor", None)}
+
     def table_metadata(self, database, table):
         "Fetch table-specific metadata."
         return (
@@ -762,6 +765,10 @@ class Datasette:
             JsonDataView.as_asgi(self, "databases.json", self._connected_databases),
             r"/-/databases(?P<as_format>(\.json)?)$",
         )
+        add_route(
+            JsonDataView.as_asgi(self, "actor.json", self._actor, needs_request=True),
+            r"/-/actor(?P<as_format>(\.json)?)$",
+        )
         add_route(
             PatternPortfolioView.as_asgi(self), r"/-/patterns$",
         )
diff --git a/datasette/views/special.py b/datasette/views/special.py
index dfe5ea8c..840473a7 100644
--- a/datasette/views/special.py
+++ b/datasette/views/special.py
@@ -6,13 +6,17 @@ from .base import BaseView
 class JsonDataView(BaseView):
     name = "json_data"
 
-    def __init__(self, datasette, filename, data_callback):
+    def __init__(self, datasette, filename, data_callback, needs_request=False):
         self.ds = datasette
         self.filename = filename
         self.data_callback = data_callback
+        self.needs_request = needs_request
 
     async def get(self, request, as_format):
-        data = self.data_callback()
+        if self.needs_request:
+            data = self.data_callback(request)
+        else:
+            data = self.data_callback()
         if as_format:
             headers = {}
             if self.ds.cors:
diff --git a/docs/introspection.rst b/docs/introspection.rst
index 3cd4a40f..e5d08dbc 100644
--- a/docs/introspection.rst
+++ b/docs/introspection.rst
@@ -10,7 +10,9 @@ Each of these pages can be viewed in your browser. Add ``.json`` to the URL to g
 /-/metadata
 -----------
 
-Shows the contents of the ``metadata.json`` file that was passed to ``datasette serve``, if any. `Metadata example <https://fivethirtyeight.datasettes.com/-/metadata>`_::
+Shows the contents of the ``metadata.json`` file that was passed to ``datasette serve``, if any. `Metadata example <https://fivethirtyeight.datasettes.com/-/metadata>`_:
+
+.. code-block:: json
 
     {
         "license": "CC Attribution 4.0 License",
@@ -18,7 +20,9 @@ Shows the contents of the ``metadata.json`` file that was passed to ``datasette
         "source": "fivethirtyeight/data on GitHub",
         "source_url": "https://github.com/fivethirtyeight/data",
         "title": "Five Thirty Eight",
-        "databases": {...}
+        "databases": {
+
+        }
     }
 
 .. _JsonDataView_versions:
@@ -26,7 +30,9 @@ Shows the contents of the ``metadata.json`` file that was passed to ``datasette
 /-/versions
 -----------
 
-Shows the version of Datasette, Python and SQLite. `Versions example <https://latest.datasette.io/-/versions>`_::
+Shows the version of Datasette, Python and SQLite. `Versions example <https://latest.datasette.io/-/versions>`_:
+
+.. code-block:: json
 
     {
         "datasette": {
@@ -63,7 +69,9 @@ Shows the version of Datasette, Python and SQLite. `Versions example <https://la
 /-/plugins
 ----------
 
-Shows a list of currently installed plugins and their versions. `Plugins example <https://san-francisco.datasettes.com/-/plugins>`_::
+Shows a list of currently installed plugins and their versions. `Plugins example <https://san-francisco.datasettes.com/-/plugins>`_:
+
+.. code-block:: json
 
     [
         {
@@ -79,7 +87,9 @@ Shows a list of currently installed plugins and their versions. `Plugins example
 /-/config
 ---------
 
-Shows the :ref:`config` options for this instance of Datasette. `Config example <https://fivethirtyeight.datasettes.com/-/config>`_::
+Shows the :ref:`config` options for this instance of Datasette. `Config example <https://fivethirtyeight.datasettes.com/-/config>`_:
+
+.. code-block:: json
 
     {
         "default_facet_size": 30,
@@ -95,7 +105,9 @@ Shows the :ref:`config` options for this instance of Datasette. `Config example
 /-/databases
 ------------
 
-Shows currently attached databases. `Databases example <https://latest.datasette.io/-/config>`_::
+Shows currently attached databases. `Databases example <https://latest.datasette.io/-/config>`_:
+
+.. code-block:: json
 
     [
         {
@@ -113,7 +125,9 @@ Shows currently attached databases. `Databases example <https://latest.datasette
 /-/threads
 ----------
 
-Shows details of threads and ``asyncio`` tasks. `Threads example <https://latest.datasette.io/-/threads>`_::
+Shows details of threads and ``asyncio`` tasks. `Threads example <https://latest.datasette.io/-/threads>`_:
+
+.. code-block:: json
 
     {
         "num_threads": 2,
@@ -136,3 +150,19 @@ Shows details of threads and ``asyncio`` tasks. `Threads example <https://latest
             "<Task pending coro=<LifespanOn.main() running at uvicorn/lifespan/on.py:48> wait_for=<Future pending cb=[<TaskWakeupMethWrapper object at 0x10364f050>()]>>"
         ]
     }
+
+.. _JsonDataView_actor:
+
+/-/actor
+--------
+
+Shows the currently authenticated actor. Useful for debugging Datasette authentication plugins.
+
+.. code-block:: json
+
+    {
+        "actor": {
+            "id": 1,
+            "username": "some-user"
+        }
+    }
diff --git a/tests/test_plugins.py b/tests/test_plugins.py
index e123b7a0..7a3fb49a 100644
--- a/tests/test_plugins.py
+++ b/tests/test_plugins.py
@@ -539,3 +539,10 @@ async def test_permission_allowed(app_client, action, expected):
         {"id": "actor"}, action, default=None
     )
     assert expected == actual
+
+
+def test_actor_json(app_client):
+    assert {"actor": None} == app_client.get("/-/actor.json").json
+    assert {"actor": {"id": "bot2", "1+1": 2}} == app_client.get(
+        "/-/actor.json/?_bot2=1"
+    ).json