diff --git a/grpc/response_test.go b/grpc/response_test.go
index d562505..3088039 100644
--- a/grpc/response_test.go
+++ b/grpc/response_test.go
@@ -1,9 +1,11 @@
-package grpc
+package grpc_test
 
 import (
 	"log"
 	"testing"
 
+	"github.com/gojek/fiber"
+	"github.com/gojek/fiber/grpc"
 	testproto "github.com/gojek/fiber/internal/testdata/gen/testdata/proto"
 	"github.com/stretchr/testify/assert"
 	"google.golang.org/grpc/codes"
@@ -15,16 +17,16 @@ import (
 func TestResponse_Backend(t *testing.T) {
 	tests := []struct {
 		name        string
-		res         Response
-		want        Response
+		res         grpc.Response
+		want        grpc.Response
 		backendName string
 	}{
 		{
 			name: "ok",
-			res: Response{
+			res: grpc.Response{
 				Metadata: map[string][]string{},
 			},
-			want: Response{
+			want: grpc.Response{
 				Metadata: metadata.New(map[string]string{"backend": "testing"}),
 			},
 			backendName: "testing",
@@ -42,13 +44,13 @@ func TestResponse_Backend(t *testing.T) {
 func TestResponse_Status(t *testing.T) {
 	tests := []struct {
 		name            string
-		res             Response
+		res             grpc.Response
 		expectedCode    int
 		expectedSuccess bool
 	}{
 		{
 			name: "ok",
-			res: Response{
+			res: grpc.Response{
 				Status: *status.New(codes.OK, ""),
 			},
 			expectedCode:    0,
@@ -56,7 +58,7 @@ func TestResponse_Status(t *testing.T) {
 		},
 		{
 			name: "ok",
-			res: Response{
+			res: grpc.Response{
 				Status: *status.New(codes.InvalidArgument, ""),
 			},
 			expectedCode:    3,
@@ -83,12 +85,12 @@ func TestResponse_Payload(t *testing.T) {
 	responseByte, _ := proto.Marshal(response)
 	tests := []struct {
 		name     string
-		req      Response
+		req      grpc.Response
 		expected []byte
 	}{
 		{
 			name: "",
-			req: Response{
+			req: grpc.Response{
 				Message: responseByte,
 			},
 			expected: responseByte,
@@ -100,3 +102,98 @@ func TestResponse_Payload(t *testing.T) {
 		})
 	}
 }
+
+func TestResponse_Label(t *testing.T) {
+	tests := map[string]struct {
+		response fiber.Response
+		key      string
+		expected []string
+	}{
+		"empty labels": {
+			response: &grpc.Response{
+				Metadata: map[string][]string{},
+			},
+			key: "dummy-key",
+		},
+		"non-empty labels": {
+			response: &grpc.Response{
+				Metadata: map[string][]string{"key": []string{"v1", "v2"}},
+			},
+			key:      "key",
+			expected: []string{"v1", "v2"},
+		},
+	}
+
+	for name, tt := range tests {
+		t.Run(name, func(t *testing.T) {
+			values := tt.response.Label(tt.key)
+			assert.Equal(t, tt.expected, values)
+		})
+	}
+}
+
+func TestResponse_WithLabel(t *testing.T) {
+	tests := map[string]struct {
+		response fiber.Response
+		key      string
+		values   []string
+		expected []string
+	}{
+		"new labels": {
+			response: &grpc.Response{
+				Metadata: map[string][]string{"key": []string{"v1", "v2"}},
+			},
+			key:      "k1",
+			values:   []string{"v1", "v2"},
+			expected: []string{"v1", "v2"},
+		},
+		"append labels": {
+			response: &grpc.Response{
+				Metadata: map[string][]string{"k1": []string{"v1", "v2"}},
+			},
+			key:      "k1",
+			values:   []string{"v3"},
+			expected: []string{"v1", "v2", "v3"},
+		},
+	}
+
+	for name, tt := range tests {
+		t.Run(name, func(t *testing.T) {
+			newLabels := tt.response.WithLabel(tt.key, tt.values...)
+			assert.Equal(t, tt.expected, newLabels.Label(tt.key))
+		})
+	}
+}
+
+func TestHTTPResponse_WithLabels(t *testing.T) {
+	tests := map[string]struct {
+		response fiber.Response
+		labels   fiber.Labels
+		key      string
+		expected []string
+	}{
+		"new labels": {
+			response: &grpc.Response{
+				Metadata: map[string][]string{"key": []string{"v1", "v2"}},
+			},
+			labels:   fiber.LabelsMap{"k1": []string{"v1", "v2"}},
+			key:      "k1",
+			expected: []string{"v1", "v2"},
+		},
+		"append labels": {
+			response: &grpc.Response{
+				Metadata: map[string][]string{"k1": []string{"v1", "v2"}},
+			},
+			labels:   fiber.LabelsMap{"k1": []string{"v3"}},
+			key:      "k1",
+			expected: []string{"v1", "v2", "v3"},
+		},
+	}
+
+	for name, tt := range tests {
+		t.Run(name, func(t *testing.T) {
+			newLabels := tt.response.WithLabels(tt.labels)
+			assert.Equal(t, tt.expected, newLabels.Label(tt.key))
+		})
+	}
+}
diff --git a/http/response_test.go b/http/response_test.go
index be9c21c..5e23b28 100644
--- a/http/response_test.go
+++ b/http/response_test.go
@@ -5,8 +5,10 @@ import (
 	"net/http"
 	"testing"
 
+	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 
+	"github.com/gojek/fiber"
 	fiberHTTP "github.com/gojek/fiber/http"
 	"github.com/gojek/fiber/internal/testutils"
 )
@@ -91,3 +93,107 @@ func TestNewHTTPResponse(t *testing.T) {
 		})
 	}
 }
+
+func TestHTTPResponseLabel(t *testing.T) {
+	tests := map[string]struct {
+		response fiber.Response
+		key      string
+		expected []string
+	}{
+		"empty labels": {
+			response: fiberHTTP.NewHTTPResponse(&http.Response{
+				Body:       makeBody([]byte("{}")),
+				StatusCode: http.StatusOK,
+			}),
+			key: "dummy-key",
+		},
+		"case insensitive key": {
+			response: fiberHTTP.NewHTTPResponse(&http.Response{
+				Header:     http.Header{"Key": []string{"v1", "v2"}},
+				Body:       makeBody([]byte("{}")),
+				StatusCode: http.StatusOK,
+			}),
+			key:      "Key",
+			expected: []string{"v1", "v2"},
+		},
+	}
+
+	for name, tt := range tests {
+		t.Run(name, func(t *testing.T) {
+			values := tt.response.Label(tt.key)
+			assert.Equal(t, tt.expected, values)
+		})
+	}
+}
+
+func TestHTTPResponseWithLabel(t *testing.T) {
+	tests := map[string]struct {
+		response fiber.Response
+		key      string
+		values   []string
+		expected []string
+	}{
+		"new labels": {
+			response: fiberHTTP.NewHTTPResponse(&http.Response{
+				Body:       makeBody([]byte("{}")),
+				StatusCode: http.StatusOK,
+			}),
+			key:      "k1",
+			values:   []string{"v1", "v2"},
+			expected: []string{"v1", "v2"},
+		},
+		"append labels": {
+			response: fiberHTTP.NewHTTPResponse(&http.Response{
+				Header:     http.Header{"K1": []string{"v1", "v2"}},
+				Body:       makeBody([]byte("{}")),
+				StatusCode: http.StatusOK,
+			}),
+			key:      "k1",
+			values:   []string{"v3"},
+			expected: []string{"v1", "v2", "v3"},
+		},
+	}
+
+	for name, tt := range tests {
+		t.Run(name, func(t *testing.T) {
+			newLabels := tt.response.WithLabel(tt.key, tt.values...)
+			assert.Equal(t, tt.expected, newLabels.Label(tt.key))
+		})
+	}
+}
+
+func TestHTTPResponseWithLabels(t *testing.T) {
+	tests := map[string]struct {
+		response fiber.Response
+		labels   fiber.Labels
+		key      string
+		expected []string
+	}{
+		"new labels": {
+			response: fiberHTTP.NewHTTPResponse(&http.Response{
+				Body:       makeBody([]byte("{}")),
+				StatusCode: http.StatusOK,
+			}),
+			labels:   fiber.LabelsMap{"k1": []string{"v1", "v2"}},
+			key:      "K1",
+			expected: []string{"v1", "v2"},
+		},
+		"append labels": {
+			response: fiberHTTP.NewHTTPResponse(&http.Response{
+				Header:     http.Header{"K1": []string{"v1", "v2"}},
+				Body:       makeBody([]byte("{}")),
+				StatusCode: http.StatusOK,
+			}),
+			labels:   fiber.LabelsMap{"k1": []string{"v3"}},
+			key:      "k1",
+			expected: []string{"v1", "v2", "v3"},
+		},
+	}
+
+	for name, tt := range tests {
+		t.Run(name, func(t *testing.T) {
+			newLabels := tt.response.WithLabels(tt.labels)
+			assert.Equal(t, tt.expected, newLabels.Label(tt.key))
+		})
+	}
+}
diff --git a/labels_test.go b/labels_test.go
new file mode 100644
index 0000000..ead1f21
--- /dev/null
+++ b/labels_test.go
@@ -0,0 +1,91 @@
+package fiber_test
+
+import (
+	"sort"
+	"testing"
+
+	"github.com/gojek/fiber"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestLabelsMapKeys(t *testing.T) {
+	tests := map[string]struct {
+		data     fiber.LabelsMap
+		expected []string
+	}{
+		"empty map": {
+			data:     fiber.LabelsMap{},
+			expected: []string{},
+		},
+		"non-empty map": {
+			data:     fiber.LabelsMap{"k1": []string{"v1", "v2"}, "k2": []string{"v3"}},
+			expected: []string{"k1", "k2"},
+		},
+	}
+
+	for name, tt := range tests {
+		t.Run(name, func(t *testing.T) {
+			keys := tt.data.Keys()
+			// Sort and compare
+			sort.Slice(keys, func(p, q int) bool {
+				return keys[p] < keys[q]
+			})
+			assert.Equal(t, tt.expected, keys)
+		})
+	}
+}
+
+func TestLabelsMapWithLabel(t *testing.T) {
+	tests := map[string]struct {
+		data     fiber.LabelsMap
+		key      string
+		values   []string
+		expected fiber.LabelsMap
+	}{
+		"set key": {
+			data:     fiber.LabelsMap{},
+			key:      "k1",
+			values:   []string{"v1", "v2"},
+			expected: fiber.LabelsMap{"k1": []string{"v1", "v2"}},
+		},
+		"overwrite key": {
+			data:     fiber.LabelsMap{"k1": []string{"v1", "v2"}, "k2": []string{"v3"}},
+			key:      "k2",
+			values:   []string{"new-val"},
+			expected: fiber.LabelsMap{"k1": []string{"v1", "v2"}, "k2": []string{"new-val"}},
+		},
+	}
+
+	for name, tt := range tests {
+		t.Run(name, func(t *testing.T) {
+			newMap := tt.data.WithLabel(tt.key, tt.values...)
+			assert.Equal(t, tt.expected, newMap)
+		})
+	}
+}
+
+func TestLabelsMapLabel(t *testing.T) {
+	tests := map[string]struct {
+		data     fiber.LabelsMap
+		key      string
+		expected []string
+	}{
+		"empty map": {
+			data:     fiber.LabelsMap{},
+			key:      "k",
+			expected: []string{},
+		},
+		"non-empty map": {
+			data:     fiber.LabelsMap{"k1": []string{"v1", "v2"}, "k2": []string{"v3"}},
+			key:      "k1",
+			expected: []string{"v1", "v2"},
+		},
+	}
+
+	for name, tt := range tests {
+		t.Run(name, func(t *testing.T) {
+			values := tt.data.Label(tt.key)
+			assert.Equal(t, tt.expected, values)
+		})
+	}
+}