diff --git a/browser.d.ts b/browser.d.ts
index 81b982e..d6495a4 100644
--- a/browser.d.ts
+++ b/browser.d.ts
@@ -1,4 +1,4 @@
-// Type definitions for pdf-merger-js v4.2.0
+// Type definitions for pdf-merger-js v5.0.0
 // Project: https://github.com/nbesli/pdf-merger-js
 // Definitions by: Alexander Wunschik <https://github.com/mojoaxel/>
 //                 Daniel Hammer <https://github.com/danmhammer/>
@@ -7,16 +7,59 @@
 declare module "pdf-merger-js/browser" {
   class PDFMerger {
     constructor();
-    add(inputFile: string | Uint8Array | ArrayBuffer | Blob | File, pages?: string | string[] | undefined | null): Promise<undefined>;
-    save(fileName: string): Promise<undefined>;
+    /**
+     * Resets the internal state of the document, to start again.
+     *
+     * @returns {void}
+     */
+    reset(): void;
+    /**
+     * Add pages from a PDF document to the end of the merged document.
+     *
+     * @async
+     * @param {PdfInput} input - a pdf source
+     * @param {string | string[] | number | number[] | undefined | null} [pages]
+     * @returns {Promise<void>}
+     */
+    add(inputFile: PdfInput, pages?: string | string[] | number | number[] | undefined | null): Promise<undefined>;
+    /**
+     * Download the PDF as a file with the given name.
+     * The extension ".pdf" is appended automatically.
+     *
+     * @async
+     * @param {string} fileName
+     * @returns {Promise<void>}
+     */
+    save(fileName: string): Promise<void>;
+    /**
+     * Return the merged PDF as a Uint8Array.
+     *
+     * @async
+     * @returns {Promise<Uint8Array>}
+     */
     saveAsBuffer(): Promise<Uint8Array>;
+    /**
+     * Return the merged PDF as a Blob.
+     *
+     * @async
+     * @returns {Promise<Blob>}
+     */
     saveAsBlob(): Promise<Blob>;
+    /**
+     * Set the metadata of the merged PDF.
+     *
+     * @async
+     * @param {Metadata} metadata
+     * @returns {Promise<void>}
+     */
     setMetadata(metadata: Metadata): Promise<void>;
   }
 
   export = PDFMerger;
 }
 
+declare type PdfInput = Uint8Array | ArrayBuffer | Blob | URL | File | String | string;
+
 declare interface Metadata {
   producer?: string
   author?: string
diff --git a/index.d.ts b/index.d.ts
index 7b87b7c..da708e3 100644
--- a/index.d.ts
+++ b/index.d.ts
@@ -1,19 +1,55 @@
-// Type definitions for pdf-merger-js v4.2.1+
+// Type definitions for pdf-merger-js v5.0.0
 // Project: https://github.com/nbesli/pdf-merger-js
 // Definitions by: Alexander Wunschik <https://github.com/mojoaxel/>
 
+import { PathLike } from "fs-extra";
+
 declare module "pdf-merger-js" {
   class PDFMerger {
     constructor();
+    /**
+     * Resets the internal state of the document, to start again.
+     *
+     * @returns {void}
+     */
     reset(): void;
-    add(inputFile: string | Buffer | ArrayBuffer, pages?: string | string[] | undefined | null): Promise<undefined>;
-    save(fileName: string): Promise<undefined>;
+    /**
+     * Add pages from a PDF document to the end of the merged document.
+     *
+     * @async
+     * @param {PdfInput} input - a pdf source
+     * @param {string | string[] | number | number[] | undefined | null} [pages]
+     * @returns {Promise<void>}
+     */
+    add(inputFile: PdfInput, pages?: string | string[] | number | number[] | undefined | null): Promise<void>;
+    /**
+     * Save the merged PDF to the given path.
+     *
+     * @async
+     * @param {string | PathLike} fileName
+     * @returns {Promise<void>}
+     */
+    save(fileName: string): Promise<void>;
+    /**
+     * Return the merged PDF as a Buffer.
+     *
+     * @async
+     * @returns {Promise<Buffer>}
+     */
     saveAsBuffer(): Promise<Buffer>;
+    /**
+     * Set the metadata of the merged PDF.
+     *
+     * @async
+     * @param {Metadata} metadata
+     * @returns {Promise<void>}
+     */
     setMetadata(metadata: Metadata): Promise<void>;
   }
   export = PDFMerger;
 }
 
+declare type PdfInput = Uint8Array | ArrayBuffer | Blob | URL | Buffer | String | PathLike | string;
 
 declare interface Metadata {
   producer?: string
diff --git a/types/index.d.ts b/types/index.d.ts
deleted file mode 100644
index 56bec63..0000000
--- a/types/index.d.ts
+++ /dev/null
@@ -1,15 +0,0 @@
-export = PDFMerger;
-declare class PDFMerger {
-    /**
-     * Resets the internal PDFDocument.
-     * Call this method if you want to start merging a new document.
-     *
-     * @returns {void}
-     */
-    reset(): void;
-    add(inputFile: any, pages: any): Promise<void>;
-    setMetadata(metadata: any): Promise<void>;
-    save(fileName: any): Promise<void>;
-    saveAsBuffer(): Promise<Buffer>;
-    #private;
-}