diff --git a/python/activator/config.py b/python/activator/config.py
index 0eb17e73..f39ec44f 100644
--- a/python/activator/config.py
+++ b/python/activator/config.py
@@ -45,7 +45,7 @@ class PipelinesConfig:
         A sequence of mappings ("nodes"), each with the following keys:
 
         ``"survey"``
-            The survey that triggers the pipelines (`str`).
+            The survey that triggers the pipelines (`str`, optional).
         ``"pipelines"``
             A list of zero or more pipelines (sequence [`str`] or `None`). Each
             pipeline path may contain environment variables, and the list of
@@ -53,7 +53,8 @@ class PipelinesConfig:
             be run.
 
         Nodes are arranged by precedence, i.e., the first node that matches a
-        visit is used.
+        visit is used. A node containing only ``pipelines`` is unconstrained
+        and matches *any* visit.
 
     Examples
     --------
@@ -112,8 +113,8 @@ def __init__(self, config: collections.abc.Mapping[str, typing.Any]):
                     raise ValueError(f"Pipelines spec must be list or None, got {pipelines_value}")
                 self._check_pipelines(self._filenames)
 
-                survey_value = specs.pop('survey')
-                if isinstance(survey_value, str):
+                survey_value = specs.pop('survey', None)
+                if isinstance(survey_value, str) or survey_value is None:
                     self._survey = survey_value
                 else:
                     raise ValueError(f"{survey_value} is not a valid survey name.")
@@ -158,7 +159,9 @@ def matches(self, visit: FannedOutVisit) -> bool:
             matches : `bool`
                 `True` if the visit meets all conditions, `False` otherwise.
             """
-            return self._survey == visit.survey
+            if self._survey is not None and self._survey != visit.survey:
+                return False
+            return True
 
         @property
         def pipeline_files(self) -> collections.abc.Sequence[str]:
diff --git a/tests/test_config.py b/tests/test_config.py
index 72e650d5..c831ea13 100644
--- a/tests/test_config.py
+++ b/tests/test_config.py
@@ -152,6 +152,12 @@ def test_duplicates(self):
             PipelinesConfig([{"survey": "TestSurvey",
                               "pipelines": ["/etc/pipelines/ApPipe.yaml", "/etc/pipelines/ApPipe.yaml#isr"]}])
 
+    def test_needpipeline(self):
+        with self.assertRaises(ValueError):
+            PipelinesConfig([{"survey": "TestSurvey"}])
+        with self.assertRaises(ValueError):
+            PipelinesConfig([{}])
+
     def test_order(self):
         config = PipelinesConfig([{"survey": "TestSurvey",
                                    "pipelines": ["/etc/pipelines/SingleFrame.yaml"],
@@ -165,3 +171,25 @@ def test_order(self):
             config.get_pipeline_files(self.visit),
             [os.path.normpath(os.path.join("/etc", "pipelines", "SingleFrame.yaml"))]
         )
+
+    def test_unconstrained(self):
+        config = PipelinesConfig([{"survey": "TestSurvey",
+                                   "pipelines": ["/etc/pipelines/SingleFrame.yaml"],
+                                   },
+                                  {"pipelines": ["${AP_PIPE_DIR}/pipelines/Isr.yaml"]},
+                                  {"survey": "", "pipelines": ["Default.yaml"]},
+                                  ])
+        self.assertEqual(
+            config.get_pipeline_files(self.visit),
+            [os.path.normpath(os.path.join("/etc", "pipelines", "SingleFrame.yaml"))]
+        )
+        self.assertEqual(
+            # Matches the second node, which has no constraints
+            config.get_pipeline_files(dataclasses.replace(self.visit, survey="CameraTest")),
+            [os.path.normpath(os.path.join(getPackageDir("ap_pipe"), "pipelines", "Isr.yaml"))]
+        )
+        self.assertEqual(
+            # Matches the second node, which has no constraints
+            config.get_pipeline_files(dataclasses.replace(self.visit, survey="")),
+            [os.path.normpath(os.path.join(getPackageDir("ap_pipe"), "pipelines", "Isr.yaml"))]
+        )