OST to PST Converter Open Source we also have a limited offer that can convert your OST files for free. In fact you can: 1. Convert one OST file to PST (incl. Emails, contacts, calendars, Tasks, Journals) 2. Our OST to PST Converter Open Source will convert the OST file in one day and you get the PST file with description on how to use it back. 3. We can convert corrupt or Orphan OST files into Outlook PST