diff --git a/lib/extensions/postgres_cdc_rls/realtime_filter_parser.ex b/lib/extensions/postgres_cdc_rls/realtime_filter_parser.ex
new file mode 100644
index 000000000..0a537fa72
--- /dev/null
+++ b/lib/extensions/postgres_cdc_rls/realtime_filter_parser.ex
@@ -0,0 +1,188 @@
+defmodule RealtimeFilterParser do
+  @moduledoc """
+  Parses Supabase realtime filter strings such as:
+
+      "date=eq.2026-02-03,published_at=not.is.null,area=eq.Oslo\\, Norway,id=in.(1,2,3)"
+
+  Splitting rules:
+
+    • The filter string is split on commas.
+    • A comma can be escaped using '\\,' and will then be treated as part of the value.
+      Example:
+          area=eq.Oslo\\, Norway
+      becomes:
+          {"area", "eq", "Oslo, Norway"}
+
+    • Commas inside parentheses are NOT treated as separators.
+      Example:
+          id=in.(1,2,3)
+
+  Supported operators:
+
+      eq, neq, lt, lte, gt, gte, in, isnull, notnull
+
+  Special cases:
+
+      is.null      → {"column", "isnull", nil}
+      not.is.null  → {"column", "notnull", nil}
+
+  Returns:
+
+      {:ok, [{column, operator, value}, ...]}
+      {:error, reason}
+  """
+
+  @filter_types ["eq", "neq", "lt", "lte", "gt", "gte", "in", "isnull", "notnull"]
+
+  @spec parse_filter(String.t() | nil) ::
+          {:ok, list({String.t(), String.t(), any()})} | {:error, String.t()}
+  def parse_filter(nil), do: {:ok, []}
+  def parse_filter(""), do: {:ok, []}
+
+  def parse_filter(filter) when is_binary(filter) do
+    with parts when is_list(parts) <- split_filter(filter),
+         {:ok, filters} <- parse_parts(parts) do
+      {:ok, filters}
+    else
+      {:error, _} = err -> err
+      other -> {:error, "unexpected parse error: #{inspect(other)}"}
+    end
+  end
+
+  # ------------------------------------------------------------
+  # Splitting logic:
+  # - split on commas unless escaped: '\,'
+  # - do not split on commas inside parentheses (for in.(...))
+  # - unescape '\,' -> ',' in each resulting part
+  # ------------------------------------------------------------
+
+  @spec split_filter(String.t()) :: [String.t()]
+  defp split_filter(filter) do
+    filter
+    |> String.graphemes()
+    |> do_split([], "", 0, false)
+    |> Enum.map(&String.trim/1)
+    |> Enum.reject(&(&1 == ""))
+    |> Enum.map(&String.replace(&1, "\\,", ","))
+  end
+
+  # acc: list of completed parts (reversed)
+  # buf: current part buffer
+  # paren_depth: nesting depth of parentheses
+  # escaped: whether previous char was '\'
+  defp do_split([], acc, buf, _paren_depth, _escaped),
+    do: Enum.reverse([buf | acc])
+
+  # split only when comma is outside parentheses and not escaped
+  defp do_split(["," | rest], acc, buf, 0, false) do
+    do_split(rest, [buf | acc], "", 0, false)
+  end
+
+  # backslash means next char is "escaped" for splitting purposes (we keep the backslash)
+  defp do_split(["\\" | rest], acc, buf, paren_depth, _escaped) do
+    do_split(rest, acc, buf <> "\\", paren_depth, true)
+  end
+
+  defp do_split(["(" | rest], acc, buf, paren_depth, _escaped) do
+    do_split(rest, acc, buf <> "(", paren_depth + 1, false)
+  end
+
+  defp do_split([")" | rest], acc, buf, paren_depth, _escaped) do
+    do_split(rest, acc, buf <> ")", max(paren_depth - 1, 0), false)
+  end
+
+  defp do_split([c | rest], acc, buf, paren_depth, _escaped) do
+    do_split(rest, acc, buf <> c, paren_depth, false)
+  end
+
+  # ------------------------------------------------------------
+  # Parsing logic
+  # ------------------------------------------------------------
+
+  @spec parse_parts([String.t()]) ::
+          {:ok, list({String.t(), String.t(), any()})} | {:error, String.t()}
+  defp parse_parts(parts) do
+    parts
+    |> Enum.reduce_while({:ok, []}, fn part, {:ok, acc} ->
+      case String.split(part, "=", parts: 2) do
+        [col, rest] ->
+          col = String.trim(col)
+
+          case parse_op_and_value(rest) do
+            {:ok, filter_type, raw_value} ->
+              if filter_type in @filter_types do
+                with {:ok, formatted} <- format_filter_value(filter_type, raw_value) do
+                  {:cont, {:ok, [{col, filter_type, formatted} | acc]}}
+                else
+                  {:error, reason} ->
+                    {:halt, {:error, "failed to parse filter '#{part}': #{reason}"}}
+                end
+              else
+                {:halt,
+                 {:error,
+                  "unsupported filter type '#{filter_type}' for part: '#{part}'. supported: #{inspect(@filter_types)}"}}
+              end
+
+            {:error, reason} ->
+              {:halt, {:error, "failed to parse filter '#{part}': #{reason}"}}
+          end
+
+        _ ->
+          {:halt, {:error, "missing '=' in filter part: '#{part}'"}}
+      end
+    end)
+    |> case do
+      {:ok, list} -> {:ok, Enum.reverse(list)}
+      other -> other
+    end
+  end
+
+  # "is.null"     => {"isnull", nil}
+  # "not.is.null" => {"notnull", nil}
+  # "<op>.<value>" => {op, value}   (value left untouched; quotes untouched)
+  @spec parse_op_and_value(String.t()) :: {:ok, String.t(), any()} | {:error, String.t()}
+  defp parse_op_and_value(rest) when is_binary(rest) do
+    rest = String.trim(rest)
+
+    case String.split(rest, ".", parts: 3) do
+      ["is", "null"] ->
+        {:ok, "isnull", nil}
+
+      ["not", "is", "null"] ->
+        {:ok, "notnull", nil}
+
+      [filter_type, raw_value] ->
+        {:ok, filter_type, raw_value}
+
+      _ ->
+        {:error, "invalid filter format, expected 'is.null', 'not.is.null', or '<op>.<value>'"}
+    end
+  end
+
+  # ------------------------------------------------------------
+  # Value formatting
+  # ------------------------------------------------------------
+
+  @spec format_filter_value(String.t(), any()) :: {:ok, any()} | {:error, String.t()}
+  defp format_filter_value(filter, value) do
+    case filter do
+      "in" ->
+        case Regex.run(~r/^\((.*)\)$/, value) do
+          nil ->
+            {:error, "`in` filter value must be wrapped by parentheses"}
+
+          [_, new_value] ->
+            {:ok, "{#{new_value}}"}
+        end
+
+      "isnull" ->
+        {:ok, nil}
+
+      "notnull" ->
+        {:ok, nil}
+
+      _ ->
+        {:ok, value}
+    end
+  end
+end
diff --git a/lib/extensions/postgres_cdc_rls/subscriptions.ex b/lib/extensions/postgres_cdc_rls/subscriptions.ex
index db6cd027b..b8f1f5365 100644
--- a/lib/extensions/postgres_cdc_rls/subscriptions.ex
+++ b/lib/extensions/postgres_cdc_rls/subscriptions.ex
@@ -11,8 +11,6 @@ defmodule Extensions.PostgresCdcRls.Subscriptions do
   @type subscription_params :: {action_filter :: binary, schema :: binary, table :: binary, [filter]}
   @type subscription_list :: [%{id: binary, claims: map, subscription_params: subscription_params}]
 
-  @filter_types ["eq", "neq", "lt", "lte", "gt", "gte", "in"]
-
   @spec create(conn(), String.t(), subscription_list, pid(), pid()) ::
           {:ok, Postgrex.Result.t()}
           | {:error, Exception.t() | {:exit, term} | {:subscription_insert_failed, String.t()}}
@@ -199,12 +197,12 @@ defmodule Extensions.PostgresCdcRls.Subscriptions do
   An unsupported filter will respond with an error tuple:
 
       iex> parse_subscription_params(%{"schema" => "public", "table" => "messages", "filter" => "subject=like.hey"})
-      {:error, ~s(Error parsing `filter` params: ["like", "hey"])}
+      {:error, ~s(Error parsing `filter` params: unsupported filter type 'like' for part: 'subject=like.hey'. supported: ["eq", "neq", "lt", "lte", "gt", "gte", "in", "isnull", "notnull"])}
 
   Catch `undefined` filters:
 
       iex> parse_subscription_params(%{"schema" => "public", "table" => "messages", "filter" => "undefined"})
-      {:error, ~s(Error parsing `filter` params: ["undefined"])}
+      {:error, ~s(Error parsing `filter` params: missing '=' in filter part: 'undefined')}
 
   Catch `missing params`:
 
@@ -220,17 +218,9 @@ defmodule Extensions.PostgresCdcRls.Subscriptions do
     case params do
       %{"schema" => schema, "table" => table, "filter" => filter}
       when is_binary(schema) and is_binary(table) and is_binary(filter) ->
-        with [col, rest] <- String.split(filter, "=", parts: 2),
-             [filter_type, value] when filter_type in @filter_types <-
-               String.split(rest, ".", parts: 2),
-             {:ok, formatted_value} <- format_filter_value(filter_type, value) do
-          {:ok, {action_filter, schema, table, [{col, filter_type, formatted_value}]}}
-        else
-          {:error, msg} ->
-            {:error, "Error parsing `filter` params: #{msg}"}
-
-          e ->
-            {:error, "Error parsing `filter` params: #{inspect(e)}"}
+        case RealtimeFilterParser.parse_filter(filter) do
+          {:ok, filters} -> {:ok, {action_filter, schema, table, filters}}
+          {:error, msg} -> {:error, "Error parsing `filter` params: #{msg}"}
         end
 
       %{"schema" => schema, "table" => table}
@@ -267,20 +257,4 @@ defmodule Extensions.PostgresCdcRls.Subscriptions do
   end
 
   defp action_filter(_), do: "*"
-
-  defp format_filter_value(filter, value) do
-    case filter do
-      "in" ->
-        case Regex.run(~r/^\((.*)\)$/, value) do
-          nil ->
-            {:error, "`in` filter value must be wrapped by parentheses"}
-
-          [_, new_value] ->
-            {:ok, "{#{new_value}}"}
-        end
-
-      _ ->
-        {:ok, value}
-    end
-  end
 end
diff --git a/lib/realtime/tenants/repo/migrations/20260213194320_support_is_null_filter.exs b/lib/realtime/tenants/repo/migrations/20260213194320_support_is_null_filter.exs
new file mode 100644
index 000000000..e4c5df74b
--- /dev/null
+++ b/lib/realtime/tenants/repo/migrations/20260213194320_support_is_null_filter.exs
@@ -0,0 +1,54 @@
+defmodule Realtime.Tenants.Migrations.SupportIsNullFilter do
+  @moduledoc false
+
+  use Ecto.Migration
+
+  def change do
+    execute("alter type realtime.equality_op add value 'isnull';")
+    execute("alter type realtime.equality_op add value 'notnull';")
+
+    execute("
+CREATE OR REPLACE FUNCTION realtime.check_equality_op(op realtime.equality_op, type_ regtype, val_1 text, val_2 text)
+ RETURNS boolean
+ LANGUAGE plpgsql
+ IMMUTABLE
+AS $function$
+      /*
+      Casts *val_1* and *val_2* as type *type_* and check the *op* condition for truthiness
+      */
+      declare
+          op_symbol text = (
+              case
+                  when op = 'eq' then '='
+                  when op = 'neq' then '!='
+                  when op = 'lt' then '<'
+                  when op = 'lte' then '<='
+                  when op = 'gt' then '>'
+                  when op = 'gte' then '>='
+                  when op = 'in' then '= any'
+                  when op = 'isnull' then 'isnull'
+                  when op = 'notnull' then 'notnull'
+                  else 'UNKNOWN OP'
+              end
+          );
+          res boolean;
+      begin
+          if op in ('isnull', 'notnull') then
+              execute format('select %L::'|| type_::text || ' ' || op_symbol, val_1) into res;
+          else
+              execute format(
+                  'select %L::'|| type_::text || ' ' || op_symbol
+                  || ' ( %L::'
+                  || (
+                      case
+                          when op = 'in' then type_::text || '[]'
+                          else type_::text end
+                  )
+                  || ')', val_1, val_2) into res;
+          end if;
+          return res;
+      end;
+      $function$
+    ")
+  end
+end
diff --git a/test/realtime/filter_parser_test.exs b/test/realtime/filter_parser_test.exs
new file mode 100644
index 000000000..3fd60c33a
--- /dev/null
+++ b/test/realtime/filter_parser_test.exs
@@ -0,0 +1,32 @@
+defmodule RealtimeFilterParserTest do
+  use ExUnit.Case, async: true
+
+  alias RealtimeFilterParser
+
+  test "parses complex filter string" do
+    input =
+      ~s/date=eq.2026-02-03,published_at=not.is.null,area=eq.Oslo\\, Norway,id=in.(1,2,3)/
+
+    assert {:ok,
+            [
+              {"date", "eq", "2026-02-03"},
+              {"published_at", "notnull", nil},
+              {"area", "eq", "Oslo, Norway"},
+              {"id", "in", "{1,2,3}"}
+            ]} = RealtimeFilterParser.parse_filter(input)
+  end
+
+  test "parses in(...) into { ... }" do
+    assert {:ok, [{"id", "in", "{1,2}"}]} = RealtimeFilterParser.parse_filter("id=in.(1,2)")
+  end
+
+  test "returns error for in without parentheses" do
+    # malformed: value not wrapped in parentheses -> should error
+    assert {:error, _} = RealtimeFilterParser.parse_filter("id=in.1,2,3")
+  end
+
+  test "empty or nil filter returns ok with empty list" do
+    assert {:ok, []} = RealtimeFilterParser.parse_filter("")
+    assert {:ok, []} = RealtimeFilterParser.parse_filter(nil)
+  end
+end
diff --git a/test/realtime_web/channels/realtime_channel_test.exs b/test/realtime_web/channels/realtime_channel_test.exs
index 3663f2acb..9fb45802d 100644
--- a/test/realtime_web/channels/realtime_channel_test.exs
+++ b/test/realtime_web/channels/realtime_channel_test.exs
@@ -168,7 +168,7 @@ defmodule RealtimeWeb.RealtimeChannelTest do
 
       assert_push "system",
                   %{
-                    message: "Error parsing `filter` params: [\"wrong\"]",
+                    message: "Error parsing `filter` params: missing '=' in filter part: 'wrong'",
                     status: "error",
                     extension: "postgres_changes",
                     channel: "test"