diff --git a/src/mutator/base.ts b/src/mutator/base.ts
new file mode 100644
index 0000000..86ee521
--- /dev/null
+++ b/src/mutator/base.ts
@@ -0,0 +1,3 @@
+export abstract class Mutator {
+  abstract execute(): Promise<Boolean>;
+}
diff --git a/src/mutator/types.ts b/src/mutator/types.ts
new file mode 100644
index 0000000..eb9e7c6
--- /dev/null
+++ b/src/mutator/types.ts
@@ -0,0 +1 @@
+export type MutatorName = "npm";