Digital signature (eSignature) made easy with GroupDocs Signature. Create your electronic digital signature and digitally esign documents!...XLS, XLSX, XLSM, XLSB, OTS, XLTX, XLTM PowerPoint: PPT, PPTX...\"xlsb\",\"xlsm\",\"xltm\",\"xltx\",\"csv\",\"bmp\",\"gif\",\"jpg\"...