The best OST to PST Converter tool eSoftTools OST to PST Converter Software as the most effective solution to convert OST to PST while preserving all data during migration, including Calendars, Tasks, and Attachments. Users can also use its free version, which allows the conversion of 25 items per folder without any cost. In addition, You can Convert OST to PST and other files types for conversion are:- Gmail, Yahoo mail, Outlook.com, Office 365, ICS, Thunderbird, Zimbra, vCard, HTML, EML, EMLX, MHTML, etc.