diff --git a/ridge.go b/ridge.go
index b96abd5..adba74d 100644
--- a/ridge.go
+++ b/ridge.go
@@ -181,22 +181,33 @@ func (r *Ridge) Run() {
 
 // RunWithContext runs http handler on AWS Lambda runtime or net/http's server with context.
 func (r *Ridge) RunWithContext(ctx context.Context) {
-	if IsOnLambdaRuntime() {
-		r.runOnLambdaRuntime(ctx)
+	if AsLambdaHandler() {
+		r.runAsLambdaHandler(ctx)
 	} else {
+		// If it is not running on the AWS Lambda runtime or running as a Lambda extension,
+		// runs a net/http server.
 		r.runOnNetHTTPServer(ctx)
 	}
 }
 
-// IsOnLambdaRuntime returns true if running on AWS Lambda runtime (excludes extensions).
+// OnLambdaRuntime returns true if running on AWS Lambda runtime
 // - AWS_EXECUTION_ENV is set on AWS Lambda runtime (go1.x)
 // - AWS_LAMBDA_RUNTIME_API is set on custom runtime (provided.*)
-// - _HANDLER is not set on AWS Lambda extension
-func IsOnLambdaRuntime() bool {
-	return (strings.HasPrefix(os.Getenv("AWS_EXECUTION_ENV"), "AWS_Lambda") || os.Getenv("AWS_LAMBDA_RUNTIME_API") != "") && os.Getenv("_HANDLER") != ""
+func OnLambdaRuntime() bool {
+	return (strings.HasPrefix(os.Getenv("AWS_EXECUTION_ENV"), "AWS_Lambda") || os.Getenv("AWS_LAMBDA_RUNTIME_API") != "")
 }
 
-func (r *Ridge) runOnLambdaRuntime(ctx context.Context) {
+// AsLambdaExtension returns true if running on AWS Lambda runtime and run as a Lambda extension
+func AsLambdaExtension() bool {
+	return OnLambdaRuntime() && os.Getenv("_HANDLER") == ""
+}
+
+// AsLambdaHandler returns true if running on AWS Lambda runtime and run as a Lambda handler
+func AsLambdaHandler() bool {
+	return OnLambdaRuntime() && os.Getenv("_HANDLER") != ""
+}
+
+func (r *Ridge) runAsLambdaHandler(ctx context.Context) {
 	handler := func(event json.RawMessage) (interface{}, error) {
 		req, err := r.RequestBuilder(event)
 		if err != nil {
diff --git a/ridge_test.go b/ridge_test.go
index 61d3314..cdc3306 100644
--- a/ridge_test.go
+++ b/ridge_test.go
@@ -6,19 +6,21 @@ import (
 	"github.com/fujiwara/ridge"
 )
 
-func TestIsOnLambdaRuntime(t *testing.T) {
+func TestRuntimeEnvironments(t *testing.T) {
 	tests := []struct {
 		name                string
 		awsExecutionEnv     string
 		awsLambdaRuntimeAPI string
 		handler             string
-		expected            bool
+		onLambdaRuntime     bool
+		asLambdaHandler     bool
+		asLambdaExtension   bool
 	}{
-		{"On AWS Lambda go runtime", "AWS_Lambda_go1.x", "", "handler", true},
-		{"On AWS Lambda custom runtime", "", "http://localhost:8080", "handler", true},
-		{"On AWS Lambda extension with go runtime", "AWS_Lambda_go1.x", "", "", false},
-		{"On AWS Lambda extension with custom runtime", "", "http://localhost:8080", "", false},
-		{"Not on AWS Lambda", "", "", "", false},
+		{"On AWS Lambda go runtime handler", "AWS_Lambda_go1.x", "", "handler", true, true, false},
+		{"On AWS Lambda custom runtime handler", "", "http://localhost:8080", "handler", true, true, false},
+		{"On AWS Lambda extension with go runtime", "AWS_Lambda_go1.x", "", "", true, false, true},
+		{"On AWS Lambda extension with custom runtime", "", "http://localhost:8080", "", true, false, true},
+		{"Not on AWS Lambda", "", "", "", false, false, false},
 	}
 
 	for _, tt := range tests {
@@ -27,8 +29,14 @@ func TestIsOnLambdaRuntime(t *testing.T) {
 			t.Setenv("AWS_LAMBDA_RUNTIME_API", tt.awsLambdaRuntimeAPI)
 			t.Setenv("_HANDLER", tt.handler)
 
-			if got := ridge.IsOnLambdaRuntime(); got != tt.expected {
-				t.Errorf("IsOnLambdaRuntime() = %v; want %v", got, tt.expected)
+			if ridge.OnLambdaRuntime() != tt.onLambdaRuntime {
+				t.Errorf("OnLambdaRuntime() = %v, want %v", ridge.OnLambdaRuntime(), tt.onLambdaRuntime)
+			}
+			if ridge.AsLambdaHandler() != tt.asLambdaHandler {
+				t.Errorf("AsLambdaHandler() = %v, want %v", ridge.AsLambdaHandler(), tt.asLambdaHandler)
+			}
+			if ridge.AsLambdaExtension() != tt.asLambdaExtension {
+				t.Errorf("AsLambdaExtension() = %v, want %v", ridge.AsLambdaExtension(), tt.asLambdaExtension)
 			}
 		})
 	}