The most reliable and top solution to convert OST file to PST format is EmailsGuru OST to PST Converter. It offers direct option to convert OST files to PST format, saving emails, contacts, calendars, attachments and all other items. Moreover, it repairs and convert corrupted inaccessible OST file without any data loss. It is capable to convert OST to PST without Outlook profile or Exchange Server. It is Windows based utility and you can also use a free trial version to convert 25 items from an OST file to PST file format.