diff --git a/package.json b/package.json
index bbf82a5..6e9c643 100644
--- a/package.json
+++ b/package.json
@@ -15,6 +15,7 @@
     "postject": "./dist/cli.js"
   },
   "main": "dist/api.js",
+  "types": "dist/api.d.ts",
   "scripts": {
     "build": "zx ./scripts/build.mjs",
     "clean": "rimraf ./build",
diff --git a/src/api.d.ts b/src/api.d.ts
new file mode 100644
index 0000000..3a75536
--- /dev/null
+++ b/src/api.d.ts
@@ -0,0 +1,16 @@
+export interface InjectOptions {
+  /**
+   * @default '__POSTJECT'
+   */
+  machoSegmentName?: string;
+  /**
+   * @default false
+   */
+  overwrite?: boolean;
+  /**
+   * @default "POSTJECT_SENTINEL_fce680ab2cc467b6e072b8b5df1996b2"
+   */
+  sentinelFuse?: string;
+}
+
+export function inject(filename: string, resourceName: string, resourceData: Buffer, options: InjectOptions): Promise<void>;