diff --git a/lib/posthog/config.ex b/lib/posthog/config.ex
index af62033..b2a2034 100644
--- a/lib/posthog/config.ex
+++ b/lib/posthog/config.ex
@@ -18,9 +18,10 @@ defmodule PostHog.Config do
                           ],
                           api_key: [
                             type: :string,
-                            required: true,
+                            default: "",
                             doc: """
                             Your PostHog Project API key. Find it in your project's settings under the Project ID section.
+                            If omitted or empty after trimming whitespace, PostHog starts in disabled/no-op mode.
                             """
                           ],
                           api_client_module: [
@@ -184,15 +185,24 @@ defmodule PostHog.Config do
 
     with {:ok, validated} <-
            NimbleOptions.validate(normalized_options, @compiled_configuration_schema) do
+      api_key_blank? = blank_api_key?(validated)
       log_blank_api_key(validated)
 
       config = Map.new(validated)
-      client = config.api_client_module.client(config.api_key, config.api_host)
+
+      client =
+        if api_key_blank? do
+          nil
+        else
+          config.api_client_module.client(config.api_key, config.api_host)
+        end
+
       global_properties = Map.merge(config.global_properties, @system_global_properties)
 
       final_config =
         config
         |> Map.put(:api_client, client)
+        |> Map.put(:enabled, not api_key_blank?)
         |> Map.put(
           :in_app_modules,
           config.in_app_otp_apps |> Enum.flat_map(&Application.spec(&1, :modules)) |> MapSet.new()
@@ -219,11 +229,21 @@ defmodule PostHog.Config do
         normalized_options
       end
     end)
+    |> then(fn normalized_options ->
+      if disabled_options?(normalized_options) and
+           not Keyword.has_key?(normalized_options, :api_host) do
+        Keyword.put(normalized_options, :api_host, @default_api_host)
+      else
+        normalized_options
+      end
+    end)
   end
 
   defp normalize_api_key(api_key) when is_binary(api_key), do: String.trim(api_key)
   defp normalize_api_key(api_key), do: api_key
 
+  defp disabled_options?(options), do: Keyword.get(options, :api_key, "") == ""
+
   defp normalize_api_host(api_host) when is_binary(api_host) do
     api_host
     |> String.trim()
@@ -235,10 +255,12 @@ defmodule PostHog.Config do
 
   defp normalize_api_host(api_host), do: api_host
 
+  defp blank_api_key?(validated), do: validated[:api_key] == ""
+
   defp log_blank_api_key(validated) do
-    if validated[:api_key] == "" do
+    if blank_api_key?(validated) do
       Logger.error(
-        "posthog api_key is empty after trimming whitespace; check your project API key"
+        "posthog api_key is empty after trimming whitespace; PostHog will start in disabled/no-op mode"
       )
     end
   end
diff --git a/lib/posthog/sender.ex b/lib/posthog/sender.ex
index b7b93c7..5d17aac 100644
--- a/lib/posthog/sender.ex
+++ b/lib/posthog/sender.ex
@@ -30,15 +30,28 @@ defmodule PostHog.Sender do
     supervisor_name
     |> PostHog.Registry.config()
     |> case do
+      %{enabled: false} ->
+        :ok
+
       %{test_mode: true} ->
         PostHog.Test.remember_event(supervisor_name, event)
 
       _ ->
-        senders =
-          supervisor_name
-          |> PostHog.Registry.registry_name()
-          |> Registry.select([{{{__MODULE__, :_}, :"$1", :"$2"}, [], [{{:"$2", :"$1"}}]}])
+        send_to_sender(event, supervisor_name)
+    end
+  end
+
+  defp send_to_sender(event, supervisor_name) do
+    senders =
+      supervisor_name
+      |> PostHog.Registry.registry_name()
+      |> Registry.select([{{{__MODULE__, :_}, :"$1", :"$2"}, [], [{{:"$2", :"$1"}}]}])
+
+    case senders do
+      [] ->
+        :ok
 
+      senders ->
         # Pick the first available sender, otherwise random busy one.
         senders
         |> Keyword.get_lazy(:available, fn ->
diff --git a/lib/posthog/supervisor.ex b/lib/posthog/supervisor.ex
index 91da77a..28ed1e5 100644
--- a/lib/posthog/supervisor.ex
+++ b/lib/posthog/supervisor.ex
@@ -37,6 +37,8 @@ defmodule PostHog.Supervisor do
     Supervisor.init(children, strategy: :one_for_one)
   end
 
+  defp sources(%{enabled: false}), do: []
+
   defp sources(config) do
     if config.enable_source_code_context do
       opts = [
@@ -53,6 +55,8 @@ defmodule PostHog.Supervisor do
     end
   end
 
+  defp senders(%{enabled: false}), do: []
+
   defp senders(config) do
     pool_size = Map.get(config, :sender_pool_size, max(System.schedulers_online(), 2))
 
diff --git a/test/posthog/application_config_test.exs b/test/posthog/application_config_test.exs
new file mode 100644
index 0000000..9db9533
--- /dev/null
+++ b/test/posthog/application_config_test.exs
@@ -0,0 +1,41 @@
+defmodule PostHog.ApplicationConfigTest do
+  use ExUnit.Case, async: false
+
+  import ExUnit.CaptureLog
+  import Mox
+
+  setup :verify_on_exit!
+
+  setup do
+    previous_env = Application.get_all_env(:posthog)
+
+    on_exit(fn ->
+      :posthog
+      |> Application.get_all_env()
+      |> Keyword.keys()
+      |> Enum.each(&Application.delete_env(:posthog, &1))
+
+      Enum.each(previous_env, fn {key, value} ->
+        Application.put_env(:posthog, key, value)
+      end)
+    end)
+  end
+
+  test "read! does not raise when enabled and api_key is missing" do
+    Application.put_env(:posthog, :enable, true)
+    Application.put_env(:posthog, :api_client_module, PostHog.API.Mock)
+    Application.delete_env(:posthog, :api_key)
+    Application.delete_env(:posthog, :api_host)
+
+    log =
+      capture_log(fn ->
+        assert {%{enable: true}, %{api_key: "", enabled: false, api_client: nil} = config} =
+                 PostHog.Config.read!()
+
+        assert config.api_host == "https://us.i.posthog.com"
+      end)
+
+    assert log =~
+             "posthog api_key is empty after trimming whitespace; PostHog will start in disabled/no-op mode"
+  end
+end
diff --git a/test/posthog/config_test.exs b/test/posthog/config_test.exs
index d09ef88..db3138b 100644
--- a/test/posthog/config_test.exs
+++ b/test/posthog/config_test.exs
@@ -43,14 +43,42 @@ defmodule PostHog.ConfigTest do
     assert config.api_host == "https://us.i.posthog.com"
   end
 
-  test "validate logs when api_key is blank after trimming whitespace" do
-    expect(PostHog.API.Mock, :client, fn api_key, api_host ->
-      assert api_key == ""
-      assert api_host == "https://us.i.posthog.com"
+  test "validate disables PostHog when api_key is missing" do
+    log =
+      capture_log(fn ->
+        assert {:ok, config} =
+                 PostHog.Config.validate(api_client_module: PostHog.API.Mock)
 
-      %PostHog.API.Client{client: :stub_client, module: PostHog.API.Mock}
-    end)
+        assert config.api_key == ""
+        assert config.api_host == "https://us.i.posthog.com"
+        assert config.enabled == false
+        assert config.api_client == nil
+      end)
+
+    assert log =~
+             "posthog api_key is empty after trimming whitespace; PostHog will start in disabled/no-op mode"
+  end
+
+  test "validate disables PostHog when api_key is empty" do
+    log =
+      capture_log(fn ->
+        assert {:ok, config} =
+                 PostHog.Config.validate(
+                   api_key: "",
+                   api_host: "https://us.i.posthog.com",
+                   api_client_module: PostHog.API.Mock
+                 )
+
+        assert config.api_key == ""
+        assert config.enabled == false
+        assert config.api_client == nil
+      end)
+
+    assert log =~
+             "posthog api_key is empty after trimming whitespace; PostHog will start in disabled/no-op mode"
+  end
 
+  test "validate disables PostHog when api_key is blank after trimming whitespace" do
     log =
       capture_log(fn ->
         assert {:ok, config} =
@@ -61,8 +89,11 @@ defmodule PostHog.ConfigTest do
                  )
 
         assert config.api_key == ""
+        assert config.enabled == false
+        assert config.api_client == nil
       end)
 
-    assert log =~ "posthog api_key is empty after trimming whitespace; check your project API key"
+    assert log =~
+             "posthog api_key is empty after trimming whitespace; PostHog will start in disabled/no-op mode"
   end
 end
diff --git a/test/posthog/supervisor_test.exs b/test/posthog/supervisor_test.exs
new file mode 100644
index 0000000..d38dbb0
--- /dev/null
+++ b/test/posthog/supervisor_test.exs
@@ -0,0 +1,27 @@
+defmodule PostHog.SupervisorTest do
+  use ExUnit.Case, async: true
+
+  import ExUnit.CaptureLog
+
+  @supervisor_name __MODULE__
+
+  test "disabled config starts without senders and captures as no-op" do
+    {config, _log} =
+      with_log(fn ->
+        PostHog.Config.validate!(
+          api_key: " \n\t ",
+          api_host: "https://us.i.posthog.com",
+          supervisor_name: @supervisor_name
+        )
+      end)
+
+    start_link_supervised!({PostHog.Supervisor, config})
+
+    assert [] =
+             @supervisor_name
+             |> PostHog.Registry.registry_name()
+             |> Registry.select([{{{PostHog.Sender, :_}, :"$1", :"$2"}, [], [:"$1"]}])
+
+    assert :ok = PostHog.bare_capture(@supervisor_name, "disabled capture", "distinct_id", %{})
+  end
+end