diff --git a/tildes/tests/test_ratelimit.py b/tildes/tests/test_ratelimit.py
index 0dffc5e..a606032 100644
--- a/tildes/tests/test_ratelimit.py
+++ b/tildes/tests/test_ratelimit.py
@@ -24,10 +24,15 @@ def test_all_rate_limited_action_names_unique():
         seen_names.add(action.name)
 
 
-def test_action_with_all_types_disabled():
-    """Ensure RateLimitedAction can't have both by_user and by_ip disabled."""
-    with raises(ValueError):
-        RateLimitedAction("test", timedelta(hours=1), 5, by_user=False, by_ip=False)
+def test_check_global_disabled():
+    """Ensure global check is disabled if action is by_user or by_ip."""
+    action = RateLimitedAction("test", timedelta(hours=1), 5, by_user=True, by_ip=False)
+    with raises(RateLimitError):
+        action.check_global()
+
+    action = RateLimitedAction("test", timedelta(hours=1), 5, by_user=False, by_ip=True)
+    with raises(RateLimitError):
+        action.check_global()
 
 
 def test_check_by_user_id_disabled():
@@ -53,6 +58,31 @@ def test_max_burst_with_limit_1():
     assert action.max_burst == 1
 
 
+def test_simple_global_rate_limiting(redis):
+    """Ensure simple global rate-limiting is working."""
+    limit = 5
+
+    # define an action with max_burst equal to the full limit
+    action = RateLimitedAction(
+        "testaction",
+        timedelta(hours=1),
+        limit,
+        max_burst=limit,
+        by_user=False,
+        by_ip=False,
+        redis=redis,
+    )
+
+    # run the action the full number of times, should all be allowed
+    for _ in range(limit):
+        result = action.check_global()
+        assert result.is_allowed
+
+    # try one more time, should be rejected
+    result = action.check_global()
+    assert not result.is_allowed
+
+
 def test_simple_rate_limiting_by_user_id(redis):
     """Ensure simple rate-limiting by user_id is working."""
     limit = 5
diff --git a/tildes/tildes/lib/ratelimit.py b/tildes/tildes/lib/ratelimit.py
index abdfcdd..8efa256 100644
--- a/tildes/tildes/lib/ratelimit.py
+++ b/tildes/tildes/lib/ratelimit.py
@@ -185,9 +185,6 @@ class RateLimitedAction:
         if max_burst and not 1 <= max_burst <= limit:
             raise ValueError("max_burst must be at least 1 and <= limit")
 
-        if not (by_user or by_ip):
-            raise ValueError("At least one of by_user or by_ip must be True")
-
         self.name = name
         self.period = period
         self.limit = limit
@@ -218,9 +215,16 @@ class RateLimitedAction:
         """Set the redis connection."""
         self._redis = redis_connection
 
-    def _build_redis_key(self, by_type: str, value: Any) -> str:
+    @property
+    def is_global(self) -> bool:
+        """Whether the rate limit applies globally, not to particular users or IPs."""
+        return not (self.by_user or self.by_ip)
+
+    def _build_redis_key(self, by_type: str, value: Any = None) -> str:
         """Build the Redis key where this rate limit is maintained."""
-        parts = ["ratelimit", self.name, by_type, str(value)]
+        parts = ["ratelimit", self.name, by_type]
+        if value:
+            parts.append(str(value))
 
         return ":".join(parts)
 
@@ -234,6 +238,24 @@ class RateLimitedAction:
             int(self.period.total_seconds()),
         )
 
+    def check_global(self) -> RateLimitResult:
+        """Check a global rate limit to see if anyone can perform this action."""
+        if not self.is_global:
+            raise RateLimitError("check_global called on non-global-limited action")
+
+        key = self._build_redis_key("global")
+        result = self._call_redis_command(key)
+
+        return RateLimitResult.from_redis_cell_result(result)
+
+    def reset_global(self) -> None:
+        """Reset the global ratelimit on this action."""
+        if not self.is_global:
+            raise RateLimitError("reset_global called on non-global-limited action")
+
+        key = self._build_redis_key("global")
+        self.redis.delete(key)
+
     def check_for_user_id(self, user_id: int) -> RateLimitResult:
         """Check whether a particular user_id can perform this action."""
         if not self.by_user:
diff --git a/tildes/tildes/request_methods.py b/tildes/tildes/request_methods.py
index 2a78444..7274894 100644
--- a/tildes/tildes/request_methods.py
+++ b/tildes/tildes/request_methods.py
@@ -90,6 +90,9 @@ def check_rate_limit(request: Request, action_name: str) -> RateLimitResult:
 
     results = []
 
+    if action.is_global:
+        results.append(action.check_global())
+
     if action.by_user and request.user:
         results.append(action.check_for_user_id(request.user.user_id))