diff --git a/index.d.ts b/index.d.ts
new file mode 100644
index 0000000..e7b9933
--- /dev/null
+++ b/index.d.ts
@@ -0,0 +1,52 @@
+declare module "ot-diff" {
+  class Diff {
+    /**
+     * Generates the diff.
+     * @param oldString 
+     * @param newString 
+     * @param raw 
+     */
+    public diff(oldString: string, newString: string, raw?: boolean): OtDiff;
+
+    /**
+     * Applies a transform (`insert`, `delete`, `replace` or `noop`) based on the value of diff.action.
+     */
+    public transform(value: string, transform: OtDiff): string;
+    public insert(value: string, transform: OtDiff): string;
+    public delete(value: string, transform: OtDiff): string;
+    public replace(value: string, transform: OtDiff): string;
+    public noop(value: string, transform: OtDiff): string;
+  }
+
+  export interface OtOpts {
+    newString: string;
+    oldString: string;
+    raw: boolean;
+    changeStart: number;
+    changeFromEnd: number;
+    changeEndIndexNew: number;
+    changeEndIndexOld: number;
+    charsAdded: number;
+    charsRemoved: number;
+  }
+
+  export type OtDiff = ({
+    action: 'insert',
+    start: number,
+    payload: string
+  } | {
+    action: 'delete',
+    start: number,
+    remove: number
+  } | {
+    action: 'replace',
+    start: number,
+    remove: number,
+    payload: string
+  } | {
+    action: 'noop'
+  }) & { opts?: OtOpts };
+
+  const diff: Diff;
+  export default diff;
+}