diff --git a/swh/lister/gogs/lister.py b/swh/lister/gogs/lister.py
--- a/swh/lister/gogs/lister.py
+++ b/swh/lister/gogs/lister.py
@@ -50,10 +50,15 @@
 
     Gogs API documentation: https://github.com/gogs/docs-api
 
-    The API is protected behind authentication so credentials/API tokens
-    are mandatory. It supports pagination and provides next page URL
-    through the 'next' value of the 'Link' header. The default value for
-    page size ('limit') is 10 but the maximum allowed value is 50.
+    The API may be protected behind authentication so credentials/API tokens can be
+    provided.
+
+    The lister supports pagination and provides next page URL through the 'next' value
+    of the 'Link' header. The default value for page size ('limit') is 10 but the
+    maximum allowed value is 50.
+
+    Api can usually be found at the location: https://<host>/api/v1/repos/search
+
     """
 
     LISTER_NAME = "gogs"
@@ -90,17 +95,15 @@
                 username = cred.get("username")
                 self.api_token = cred["password"]
                 logger.info("Using authentication credentials from user %s", username)
-            else:
-                # Raises an error on Gogs, or a warning on Gitea
-                self.on_anonymous_mode()
 
         self.session.headers.update({"Accept": "application/json"})
 
         if self.api_token:
             self.session.headers["Authorization"] = f"token {self.api_token}"
-
-    def on_anonymous_mode(self):
-        raise ValueError("No credentials or API token provided")
+        else:
+            logger.warning(
+                "No authentication token set in configuration, using anonymous mode"
+            )
 
     def state_from_dict(self, d: Dict[str, Any]) -> GogsListerState:
         return GogsListerState(**d)
@@ -153,7 +156,6 @@
         while next_link is not None:
             repos = self.extract_repos(body)
 
-            assert len(links) > 0, "API changed: no Link header found"
             if "next" in links:
                 next_link = links["next"]["url"]
             else:
diff --git a/swh/lister/gogs/tests/test_lister.py b/swh/lister/gogs/tests/test_lister.py
--- a/swh/lister/gogs/tests/test_lister.py
+++ b/swh/lister/gogs/tests/test_lister.py
@@ -139,16 +139,16 @@
 def test_gogs_auth_instance(
     swh_scheduler, requests_mock, trygogs_p1, trygogs_p2, trygogs_p3_empty
 ):
-    """Covers token authentication, token from credentials,
+    """Covers without authentication, token authentication, token from credentials,
     instance inference from URL."""
 
     api_token = "secret"
     instance = "try_gogs"
 
     # Test lister initialization without api_token or credentials:
-    with pytest.raises(ValueError, match="No credentials or API token provided"):
-        kwargs1 = dict(url=TRY_GOGS_URL, instance=instance)
-        GogsLister(scheduler=swh_scheduler, **kwargs1)
+    kwargs1 = dict(url=TRY_GOGS_URL, instance=instance)
+    lister = GogsLister(scheduler=swh_scheduler, **kwargs1)
+    assert "Authorization" not in lister.session.headers
 
     # Test lister initialization using api_token:
     kwargs2 = dict(url=TRY_GOGS_URL, api_token=api_token, instance=instance)