diff --git a/CHANGELOG.md b/CHANGELOG.md
index e706b1fa..5bc38e33 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -11,6 +11,7 @@ All notable changes to this project will be documented in this file.
 - Show check's code instead of full URL on 992px - 1200px wide screens. (#253)
 - Add WhatsApp integration (uses Twilio same as the SMS integration)
 - Webhooks support the $TAGS placeholder
+- Don't include ping URLs in API responses when the read-only key is used
 
 ### Bug Fixes
 - Fix badges for tags containing special characters (#240, #237)
diff --git a/hc/api/decorators.py b/hc/api/decorators.py
index bf6c5718..b686f349 100644
--- a/hc/api/decorators.py
+++ b/hc/api/decorators.py
@@ -27,6 +27,7 @@ def authorize(f):
         except Project.DoesNotExist:
             return error("wrong api key", 401)
 
+        request.readonly = False
         return f(request, *args, **kwds)
 
     return wrapper
@@ -50,6 +51,7 @@ def authorize_read(f):
         except Project.DoesNotExist:
             return error("wrong api key", 401)
 
+        request.readonly = api_key == request.project.api_key_readonly
         return f(request, *args, **kwds)
 
     return wrapper
diff --git a/hc/api/models.py b/hc/api/models.py
index 08daa68c..62b80f2d 100644
--- a/hc/api/models.py
+++ b/hc/api/models.py
@@ -167,26 +167,34 @@ class Check(models.Model):
     def matches_tag_set(self, tag_set):
         return tag_set.issubset(self.tags_list())
 
-    def to_dict(self):
-        update_rel_url = reverse("hc-api-update", args=[self.code])
-        pause_rel_url = reverse("hc-api-pause", args=[self.code])
-        channel_codes = [str(ch.code) for ch in self.channel_set.all()]
+    def channels_str(self):
+        """ Return a comma-separated string of assigned channel codes. """
+
+        codes = self.channel_set.order_by("code").values_list("code", flat=True)
+        return ",".join(map(str, codes))
+
+    def to_dict(self, readonly=False):
 
         result = {
             "name": self.name,
-            "ping_url": self.url(),
-            "update_url": settings.SITE_ROOT + update_rel_url,
-            "pause_url": settings.SITE_ROOT + pause_rel_url,
             "tags": self.tags,
             "grace": int(self.grace.total_seconds()),
             "n_pings": self.n_pings,
             "status": self.get_status(),
-            "channels": ",".join(sorted(channel_codes)),
             "last_ping": isostring(self.last_ping),
             "next_ping": isostring(self.get_grace_start()),
-            "desc": self.desc,
         }
 
+        if not readonly:
+            update_rel_url = reverse("hc-api-update", args=[self.code])
+            pause_rel_url = reverse("hc-api-pause", args=[self.code])
+
+            result["ping_url"] = self.url()
+            result["update_url"] = settings.SITE_ROOT + update_rel_url
+            result["pause_url"] = settings.SITE_ROOT + pause_rel_url
+            result["channels"] = self.channels_str()
+            result["desc"] = self.desc
+
         if self.kind == "simple":
             result["timeout"] = int(self.timeout.total_seconds())
         elif self.kind == "cron":
diff --git a/hc/api/tests/test_list_channels.py b/hc/api/tests/test_list_channels.py
index 0458aed6..17bfa65d 100644
--- a/hc/api/tests/test_list_channels.py
+++ b/hc/api/tests/test_list_channels.py
@@ -51,10 +51,3 @@ class ListChannelsTestCase(BaseTestCase):
 
         self.assertEqual(r.status_code, 200)
         self.assertContains(r, "Email to Alice")
-
-    def test_readonly_key_works(self):
-        self.project.api_key_readonly = "R" * 32
-        self.project.save()
-
-        r = self.client.get("/api/v1/channels/", HTTP_X_API_KEY="R" * 32)
-        self.assertEqual(r.status_code, 200)
diff --git a/hc/api/tests/test_list_checks.py b/hc/api/tests/test_list_checks.py
index e6c69074..c887e267 100644
--- a/hc/api/tests/test_list_checks.py
+++ b/hc/api/tests/test_list_checks.py
@@ -150,3 +150,6 @@ class ListChecksTestCase(BaseTestCase):
 
         r = self.client.get("/api/v1/checks/", HTTP_X_API_KEY="R" * 32)
         self.assertEqual(r.status_code, 200)
+
+        # When using readonly keys, the ping URLs should not be exposed:
+        self.assertNotContains(r, self.a1.url())
diff --git a/hc/api/views.py b/hc/api/views.py
index 38a5a2e6..0520f1d9 100644
--- a/hc/api/views.py
+++ b/hc/api/views.py
@@ -121,7 +121,7 @@ def get_checks(request):
     for check in q:
         # precise, final filtering
         if not tags or check.matches_tag_set(tags):
-            checks.append(check.to_dict())
+            checks.append(check.to_dict(readonly=request.readonly))
 
     return JsonResponse({"checks": checks})
 
@@ -153,7 +153,7 @@ def checks(request):
 
 @cors("GET")
 @validate_json()
-@authorize_read
+@authorize
 def channels(request):
     q = Channel.objects.filter(project=request.project)
     channels = [ch.to_dict() for ch in q]