Opt ost to pst converter open source software from Vartika. It is great way to convert ost to pst file online. By using this conversion tool, all MS Outlook users can deeply scans MS Outlook OST file to recover damaged OST file without missing any items. The OST to PST export tool to converts Outlook OST file not only in PST file formats but also in various other file formats such that MSG, MBOX, EML, EMLX, HTML, NSF, PDF, vCard, vCal, Office365, Gmail, Yahoo & AOL and Live Exchange Server, etc. Freeware Outlook OST to PST Converter allows you to freely convert the first 30 items from every folder.