diff --git a/test/towerops/gaiia/client_test.exs b/test/towerops/gaiia/client_test.exs
index 2271f1a7..de5ceeb8 100644
--- a/test/towerops/gaiia/client_test.exs
+++ b/test/towerops/gaiia/client_test.exs
@@ -193,5 +193,70 @@ defmodule Towerops.Gaiia.ClientTest do
 
       assert {:error, {:rate_limited, 30}} = Client.query("test-key", "{ viewer { id } }")
     end
+
+    test "handles unexpected status codes" do
+      Req.Test.stub(Client, fn conn ->
+        conn
+        |> Plug.Conn.put_status(502)
+        |> Req.Test.json(%{"error" => "bad gateway"})
+      end)
+
+      assert {:error, {:unexpected_status, 502}} = Client.query("test-key", "{ viewer { id } }")
+    end
+
+    test "sends correct headers" do
+      Req.Test.stub(Client, fn conn ->
+        api_key = Plug.Conn.get_req_header(conn, "x-gaiia-api-key")
+        assert api_key == ["my-api-key"]
+
+        content_type = Plug.Conn.get_req_header(conn, "content-type")
+        assert content_type == ["application/json"]
+
+        Req.Test.json(conn, %{"data" => %{}})
+      end)
+
+      Client.query("my-api-key", "{ viewer { id } }")
+    end
+  end
+
+  describe "create_ticket/3" do
+    test "creates a ticket via mutation" do
+      Req.Test.stub(Client, fn conn ->
+        {:ok, body, _conn} = Plug.Conn.read_body(conn)
+        decoded = Jason.decode!(body)
+        assert String.contains?(decoded["query"], "createExternalTicket")
+        assert decoded["variables"]["subject"] == "Test ticket"
+
+        Req.Test.json(conn, %{
+          "data" => %{
+            "createExternalTicket" => %{
+              "id" => "ticket-1",
+              "subject" => "Test ticket"
+            }
+          }
+        })
+      end)
+
+      assert {:ok, data} = Client.create_ticket("test-key", %{"subject" => "Test ticket", "description" => "Details"})
+      assert data["createExternalTicket"]["id"] == "ticket-1"
+    end
+  end
+
+  describe "create_note/5" do
+    test "creates a note on an entity" do
+      Req.Test.stub(Client, fn conn ->
+        {:ok, body, _conn} = Plug.Conn.read_body(conn)
+        decoded = Jason.decode!(body)
+        assert decoded["variables"]["entityId"] == "acct-1"
+        assert decoded["variables"]["entityType"] == "Account"
+        assert decoded["variables"]["body"] == "Test note"
+
+        Req.Test.json(conn, %{
+          "data" => %{"createNote" => %{"id" => "note-1"}}
+        })
+      end)
+
+      assert {:ok, _} = Client.create_note("test-key", "Account", "acct-1", "Test note")
+    end
   end
 end
diff --git a/test/towerops/gaiia/sync_test.exs b/test/towerops/gaiia/sync_test.exs
index 70b4d906..d53631fb 100644
--- a/test/towerops/gaiia/sync_test.exs
+++ b/test/towerops/gaiia/sync_test.exs
@@ -97,7 +97,7 @@ defmodule Towerops.Gaiia.SyncTest do
     end
 
     test "handles API that returns null when after variable is null", %{
-      org: org,
+      org: _org,
       integration: integration
     } do
       # Some Gaiia endpoints return null for the root key when $after is null
diff --git a/test/towerops/splynx/client_test.exs b/test/towerops/splynx/client_test.exs
new file mode 100644
index 00000000..0344b159
--- /dev/null
+++ b/test/towerops/splynx/client_test.exs
@@ -0,0 +1,366 @@
+defmodule Towerops.Splynx.ClientTest do
+  use Towerops.DataCase, async: true
+
+  alias Towerops.Splynx.Client
+
+  @instance_url "https://demo.splynx.com"
+  @api_key "test_api_key"
+  @api_secret "test_api_secret"
+
+  describe "authenticate/3" do
+    test "succeeds with api_key auth type" do
+      Req.Test.stub(Client, fn conn ->
+        {:ok, body, conn} = Plug.Conn.read_body(conn)
+        decoded = Jason.decode!(body)
+
+        assert decoded["auth_type"] == "api_key"
+        assert decoded["key"] == @api_key
+        assert decoded["secret"] == @api_secret
+
+        conn
+        |> Plug.Conn.put_status(201)
+        |> Req.Test.json(auth_success_response())
+      end)
+
+      assert {:ok, "test_jwt_token_abc123"} = Client.authenticate(@instance_url, @api_key, @api_secret)
+    end
+
+    test "falls back to admin auth when api_key auth fails" do
+      call_count = :counters.new(1, [:atomics])
+
+      Req.Test.stub(Client, fn conn ->
+        {:ok, body, conn} = Plug.Conn.read_body(conn)
+        decoded = Jason.decode!(body)
+        :counters.add(call_count, 1, 1)
+        count = :counters.get(call_count, 1)
+
+        if count == 1 do
+          # First call: api_key auth fails
+          assert decoded["auth_type"] == "api_key"
+
+          conn
+          |> Plug.Conn.put_status(401)
+          |> Req.Test.json(%{"error" => %{"code" => 401, "message" => "Authentication failed!"}})
+        else
+          # Second call: admin auth succeeds
+          assert decoded["auth_type"] == "admin"
+          assert decoded["login"] == @api_key
+          assert decoded["password"] == @api_secret
+
+          conn
+          |> Plug.Conn.put_status(201)
+          |> Req.Test.json(auth_success_response())
+        end
+      end)
+
+      assert {:ok, "test_jwt_token_abc123"} = Client.authenticate(@instance_url, @api_key, @api_secret)
+    end
+
+    test "returns error when both auth types fail" do
+      Req.Test.stub(Client, fn conn ->
+        conn
+        |> Plug.Conn.put_status(401)
+        |> Req.Test.json(%{"error" => %{"code" => 401, "message" => "Authentication failed!"}})
+      end)
+
+      assert {:error, :unauthorized} = Client.authenticate(@instance_url, "bad", "creds")
+    end
+
+    test "returns error on rate limit" do
+      Req.Test.stub(Client, fn conn ->
+        conn
+        |> Plug.Conn.put_status(429)
+        |> Req.Test.json(%{"error" => "rate limited"})
+      end)
+
+      assert {:error, {:rate_limited, 60}} = Client.authenticate(@instance_url, @api_key, @api_secret)
+    end
+  end
+
+  describe "test_connection/3" do
+    test "returns ok on successful connection" do
+      stub_auth_then(fn conn ->
+        Req.Test.json(conn, [%{"id" => 1, "name" => "Clark Willis"}])
+      end)
+
+      assert {:ok, %{}} = Client.test_connection(@instance_url, @api_key, @api_secret)
+    end
+
+    test "returns error on unauthorized" do
+      Req.Test.stub(Client, fn conn ->
+        conn
+        |> Plug.Conn.put_status(401)
+        |> Req.Test.json(%{"error" => %{"code" => 401, "message" => "Authentication failed!"}})
+      end)
+
+      assert {:error, :unauthorized} = Client.test_connection(@instance_url, "bad", "creds")
+    end
+  end
+
+  describe "list_customers/3" do
+    test "returns customers from single page" do
+      stub_auth_then(fn conn ->
+        Req.Test.json(conn, customers_response())
+      end)
+
+      assert {:ok, customers} = Client.list_customers(@instance_url, @api_key, @api_secret)
+      assert length(customers) == 3
+      assert Enum.map(customers, & &1["name"]) == ["Clark Willis", "Eugene Castro", "Nelson Jackson"]
+    end
+
+    test "handles paginated results" do
+      call_count = :counters.new(1, [:atomics])
+
+      stub_auth_then(fn conn ->
+        :counters.add(call_count, 1, 1)
+        count = :counters.get(call_count, 1)
+
+        if count == 1 do
+          # Return exactly 100 to trigger pagination
+          items = Enum.map(1..100, fn i ->
+            %{"id" => i, "name" => "Customer #{i}", "status" => "active", "mrr_total" => "50.0000"}
+          end)
+
+          Req.Test.json(conn, items)
+        else
+          # Second page: less than 100, stops pagination
+          Req.Test.json(conn, [
+            %{"id" => 101, "name" => "Customer 101", "status" => "active", "mrr_total" => "50.0000"}
+          ])
+        end
+      end)
+
+      assert {:ok, customers} = Client.list_customers(@instance_url, @api_key, @api_secret)
+      assert length(customers) == 101
+    end
+
+    test "returns error on API failure" do
+      stub_auth_then(fn conn ->
+        conn
+        |> Plug.Conn.put_status(401)
+        |> Req.Test.json(%{"error" => "unauthorized"})
+      end)
+
+      assert {:error, :unauthorized} = Client.list_customers(@instance_url, @api_key, @api_secret)
+    end
+
+    test "verifies customer response shape matches real API" do
+      stub_auth_then(fn conn ->
+        Req.Test.json(conn, customers_response())
+      end)
+
+      {:ok, [first | _]} = Client.list_customers(@instance_url, @api_key, @api_secret)
+
+      # These fields come from the real Splynx demo API
+      assert first["id"] == 1
+      assert first["name"] == "Clark Willis"
+      assert first["status"] == "active"
+      assert first["mrr_total"] == "200.0000"
+      assert first["billing_type"] == "recurring"
+      assert first["email"] == "clark.willis@ispframework.com"
+      assert first["city"] == "Praha 5"
+    end
+  end
+
+  describe "list_routers/3" do
+    test "returns routers" do
+      stub_auth_then(fn conn ->
+        Req.Test.json(conn, routers_response())
+      end)
+
+      assert {:ok, routers} = Client.list_routers(@instance_url, @api_key, @api_secret)
+      assert length(routers) == 2
+      assert hd(routers)["title"] == "WiFi router"
+      assert hd(routers)["ip"] == "10.0.20.1"
+    end
+  end
+
+  describe "list_customer_services/4" do
+    test "returns services for a customer" do
+      stub_auth_then(fn conn ->
+        Req.Test.json(conn, customer_services_response())
+      end)
+
+      assert {:ok, services} = Client.list_customer_services(@instance_url, @api_key, @api_secret, 1)
+      assert length(services) == 1
+
+      [service] = services
+      assert service["description"] == "Internet - ADSL 2MB/1MB"
+      assert service["unit_price"] == "200.0000"
+      assert service["status"] == "active"
+      assert service["customer_id"] == 1
+    end
+  end
+
+  describe "authorization header" do
+    test "uses Splynx-EA format with access token" do
+      Req.Test.stub(Client, fn conn ->
+        case conn.request_path do
+          "/api/2.0/admin/auth/tokens" ->
+            conn
+            |> Plug.Conn.put_status(201)
+            |> Req.Test.json(auth_success_response())
+
+          _ ->
+            # Verify the auth header format
+            auth = Plug.Conn.get_req_header(conn, "authorization")
+            assert auth == ["Splynx-EA (access_token=test_jwt_token_abc123)"]
+
+            Req.Test.json(conn, [%{"id" => 1}])
+        end
+      end)
+
+      Client.list_customers(@instance_url, @api_key, @api_secret)
+    end
+  end
+
+  # --- Helpers ---
+
+  defp stub_auth_then(data_fn) do
+    Req.Test.stub(Client, fn conn ->
+      case conn.request_path do
+        "/api/2.0/admin/auth/tokens" ->
+          conn
+          |> Plug.Conn.put_status(201)
+          |> Req.Test.json(auth_success_response())
+
+        _ ->
+          data_fn.(conn)
+      end
+    end)
+  end
+
+  # Real response shapes captured from demo.splynx.com
+
+  defp auth_success_response do
+    %{
+      "access_token" => "test_jwt_token_abc123",
+      "refresh_token" => "test_refresh_token_abc123",
+      "access_token_expiration" => 1_771_195_460,
+      "refresh_token_expiration" => 1_771_798_460,
+      "permissions" => %{
+        "admin\\customers\\Customer" => %{
+          "index" => "allow",
+          "view" => "allow"
+        }
+      }
+    }
+  end
+
+  defp customers_response do
+    [
+      %{
+        "id" => 1,
+        "name" => "Clark Willis",
+        "email" => "clark.willis@ispframework.com",
+        "billing_email" => "clark.willis@ispframework.com",
+        "phone" => "",
+        "status" => "active",
+        "billing_type" => "recurring",
+        "mrr_total" => "200.0000",
+        "partner_id" => 2,
+        "location_id" => 1,
+        "login" => "000001",
+        "category" => "person",
+        "street_1" => "Voskovcova 1130/28",
+        "zip_code" => "15200",
+        "city" => "Praha 5",
+        "date_add" => "2015-10-21",
+        "account_type" => "regular"
+      },
+      %{
+        "id" => 2,
+        "name" => "Eugene Castro",
+        "email" => "eugene.castro@ispframework.com",
+        "billing_email" => "eugene.castro@ispframework.com",
+        "phone" => "",
+        "status" => "disabled",
+        "billing_type" => "recurring",
+        "mrr_total" => "0.0000",
+        "partner_id" => 1,
+        "location_id" => 2,
+        "login" => "000002",
+        "category" => "person",
+        "street_1" => "Ostrovskeho 1194/21",
+        "zip_code" => "15000",
+        "city" => "Praha 5",
+        "date_add" => "2015-10-21",
+        "account_type" => "regular"
+      },
+      %{
+        "id" => 3,
+        "name" => "Nelson Jackson",
+        "email" => "nelson.jackson@ispframework.com",
+        "billing_email" => "nelson.jackson@ispframework.com",
+        "phone" => "",
+        "status" => "active",
+        "billing_type" => "recurring",
+        "mrr_total" => "300.0000",
+        "partner_id" => 1,
+        "location_id" => 3,
+        "login" => "000003",
+        "category" => "person",
+        "street_1" => "Jeremiasova 2631/16c",
+        "zip_code" => "15500",
+        "city" => "Praha 5",
+        "date_add" => "2015-10-21",
+        "account_type" => "regular"
+      }
+    ]
+  end
+
+  defp routers_response do
+    [
+      %{
+        "id" => 1,
+        "title" => "WiFi router",
+        "model" => "RB n",
+        "location_id" => 1,
+        "address" => "",
+        "ip" => "10.0.20.1",
+        "gps" => nil,
+        "authorization_method" => "dhcp_leases",
+        "accounting_method" => "mikrotik_api",
+        "nas_type" => 1,
+        "status" => nil,
+        "partners_ids" => [1, 2]
+      },
+      %{
+        "id" => 2,
+        "title" => "Demo CHR",
+        "model" => "",
+        "location_id" => 5,
+        "address" => "",
+        "ip" => "10.10.10.12",
+        "gps" => nil,
+        "authorization_method" => "ppp_secrets",
+        "accounting_method" => "mikrotik_api",
+        "nas_type" => 1,
+        "status" => nil,
+        "partners_ids" => [1, 2]
+      }
+    ]
+  end
+
+  defp customer_services_response do
+    [
+      %{
+        "id" => 4,
+        "type" => "internet",
+        "customer_id" => 1,
+        "tariff_id" => 2,
+        "description" => "Internet - ADSL 2MB/1MB",
+        "quantity" => 1,
+        "unit_price" => "200.0000",
+        "start_date" => "2026-01-01",
+        "end_date" => "0000-00-00",
+        "status" => "active",
+        "login" => "000001",
+        "router_id" => 0,
+        "mac" => "",
+        "ipv4" => "",
+        "taking_ipv4" => "0"
+      }
+    ]
+  end
+end
diff --git a/test/towerops/splynx/sync_test.exs b/test/towerops/splynx/sync_test.exs
new file mode 100644
index 00000000..2631d217
--- /dev/null
+++ b/test/towerops/splynx/sync_test.exs
@@ -0,0 +1,210 @@
+defmodule Towerops.Splynx.SyncTest do
+  use Towerops.DataCase, async: true
+
+  import Towerops.AccountsFixtures
+  import Towerops.IntegrationsFixtures
+  import Towerops.OrganizationsFixtures
+
+  alias Towerops.Splynx.Client
+  alias Towerops.Splynx.Sync
+
+  setup do
+    user = user_fixture()
+    org = organization_fixture(user.id)
+
+    integration =
+      integration_fixture(org.id, %{
+        provider: "splynx",
+        credentials: %{
+          "instance_url" => "https://demo.splynx.com",
+          "api_key" => "test_key",
+          "api_secret" => "test_secret"
+        }
+      })
+
+    %{org: org, integration: integration}
+  end
+
+  describe "sync_organization/1" do
+    test "syncs customers and routers", %{integration: integration} do
+      stub_splynx_api()
+
+      assert {:ok, result} = Sync.sync_organization(integration)
+      assert result.customers == 3
+      assert result.routers == 2
+
+      updated = Repo.reload!(integration)
+      assert updated.last_sync_status == "success"
+      assert updated.last_synced_at
+      assert updated.last_sync_message =~ "3 customers"
+      assert updated.last_sync_message =~ "2 active"
+      assert updated.last_sync_message =~ "2 routers"
+    end
+
+    test "calculates MRR from customer mrr_total fields", %{integration: integration} do
+      stub_splynx_api()
+
+      {:ok, _} = Sync.sync_organization(integration)
+
+      updated = Repo.reload!(integration)
+      # 200.0000 + 0.0000 + 300.0000 = 500.00
+      assert updated.last_sync_message =~ "MRR: $500.00"
+    end
+
+    test "marks sync as failed on auth error", %{integration: integration} do
+      Req.Test.stub(Client, fn conn ->
+        conn
+        |> Plug.Conn.put_status(401)
+        |> Req.Test.json(%{"error" => %{"code" => 401, "message" => "Authentication failed!"}})
+      end)
+
+      assert {:error, :unauthorized} = Sync.sync_organization(integration)
+
+      updated = Repo.reload!(integration)
+      assert updated.last_sync_status == "failed"
+      assert updated.last_sync_message =~ "Authentication failed"
+    end
+
+    test "marks sync as failed on rate limit", %{integration: integration} do
+      stub_auth_then(fn conn ->
+        conn
+        |> Plug.Conn.put_status(429)
+        |> Req.Test.json(%{"error" => "rate limited"})
+      end)
+
+      assert {:error, {:rate_limited, 60}} = Sync.sync_organization(integration)
+
+      updated = Repo.reload!(integration)
+      assert updated.last_sync_status == "failed"
+      assert updated.last_sync_message =~ "Rate limited"
+    end
+
+    test "handles zero MRR gracefully", %{integration: integration} do
+      stub_auth_then_routes(%{
+        "customer" => [%{"id" => 1, "name" => "Test", "status" => "active", "mrr_total" => "0.0000"}],
+        "routers" => []
+      })
+
+      {:ok, _} = Sync.sync_organization(integration)
+
+      updated = Repo.reload!(integration)
+      # Should not contain MRR section when total is 0
+      refute updated.last_sync_message =~ "MRR"
+    end
+
+    test "handles customers with nil mrr_total", %{integration: integration} do
+      stub_auth_then_routes(%{
+        "customer" => [%{"id" => 1, "name" => "Test", "status" => "active", "mrr_total" => nil}],
+        "routers" => []
+      })
+
+      {:ok, result} = Sync.sync_organization(integration)
+      assert result.customers == 1
+    end
+
+    test "handles customers with numeric mrr_total", %{integration: integration} do
+      stub_auth_then_routes(%{
+        "customer" => [%{"id" => 1, "name" => "Test", "status" => "active", "mrr_total" => 150.0}],
+        "routers" => []
+      })
+
+      {:ok, _} = Sync.sync_organization(integration)
+
+      updated = Repo.reload!(integration)
+      assert updated.last_sync_message =~ "MRR: $150.00"
+    end
+  end
+
+  # --- Helpers ---
+
+  defp stub_splynx_api do
+    stub_auth_then_routes(%{
+      "customer" => customers_response(),
+      "routers" => routers_response()
+    })
+  end
+
+  defp stub_auth_then(data_fn) do
+    Req.Test.stub(Client, fn conn ->
+      case conn.request_path do
+        "/api/2.0/admin/auth/tokens" ->
+          conn
+          |> Plug.Conn.put_status(201)
+          |> Req.Test.json(auth_success_response())
+
+        _ ->
+          data_fn.(conn)
+      end
+    end)
+  end
+
+  defp stub_auth_then_routes(routes) do
+    Req.Test.stub(Client, fn conn ->
+      case conn.request_path do
+        "/api/2.0/admin/auth/tokens" ->
+          conn
+          |> Plug.Conn.put_status(201)
+          |> Req.Test.json(auth_success_response())
+
+        path ->
+          data =
+            cond do
+              String.contains?(path, "/customer") -> Map.get(routes, "customer", [])
+              String.contains?(path, "/routers") -> Map.get(routes, "routers", [])
+              true -> []
+            end
+
+          Req.Test.json(conn, data)
+      end
+    end)
+  end
+
+  defp auth_success_response do
+    %{
+      "access_token" => "test_jwt_token",
+      "refresh_token" => "test_refresh",
+      "access_token_expiration" => 1_771_195_460,
+      "refresh_token_expiration" => 1_771_798_460,
+      "permissions" => %{}
+    }
+  end
+
+  defp customers_response do
+    [
+      %{
+        "id" => 1,
+        "name" => "Clark Willis",
+        "status" => "active",
+        "mrr_total" => "200.0000",
+        "billing_type" => "recurring",
+        "email" => "clark.willis@ispframework.com",
+        "city" => "Praha 5"
+      },
+      %{
+        "id" => 2,
+        "name" => "Eugene Castro",
+        "status" => "disabled",
+        "mrr_total" => "0.0000",
+        "billing_type" => "recurring",
+        "email" => "eugene.castro@ispframework.com",
+        "city" => "Praha 5"
+      },
+      %{
+        "id" => 3,
+        "name" => "Nelson Jackson",
+        "status" => "active",
+        "mrr_total" => "300.0000",
+        "billing_type" => "recurring",
+        "email" => "nelson.jackson@ispframework.com",
+        "city" => "Praha 5"
+      }
+    ]
+  end
+
+  defp routers_response do
+    [
+      %{"id" => 1, "title" => "WiFi router", "ip" => "10.0.20.1"},
+      %{"id" => 2, "title" => "Demo CHR", "ip" => "10.10.10.12"}
+    ]
+  end
+end