diff --git a/index.d.ts b/index.d.ts
new file mode 100644
index 0000000..1736506
--- /dev/null
+++ b/index.d.ts
@@ -0,0 +1,19 @@
+export interface County {
+  id: string;
+  name: string;
+}
+export interface Zipcode {
+  id: string;
+  zipcode: number;
+  county: string;
+  city: string;
+}
+
+export interface TwZipcodeData {
+  counties: County[];
+  zipcodes: Zipcode[];
+}
+
+declare function twzipcode(locale?: string): TwZipcodeData;
+
+export default twzipcode;