For best and secure OST to PST conversion using,  ost to pst converter open source  Tool. The tool provides multiple features like It converts multiple OST files to PST, without any intrusion and also exports data into PST file, office 365, Live Exchange server, Gmail, OLM, NSF, EMLX, vCal, vCard, EML, MSG, HTML, Zimbra, PDF, MBOX, and etc.  formats. The tool OST to PST converter also recovers the deleted and corrupted OST data items and converts them into PST. free unlimited ost to pst converter  tool works with all versions of Outlook, and Windows Operating System. Download its free trial version and convert the first 30 items per folder.