Data Recovery Freeware OST to PST converter is the best tool to convert OST to PST into different file formats such as PST, PDF, DOC, DOCX, HTML, MBOX, DOCM, MHTML, etc. It also helps to convert OST file in bulk without any file size restrictions. However, this tool migrates the OST file to the number of email clients like Office 365, Thunderbird, Yahoo Mail, Gmail, Apple Mail, etc. It also compatible with all the version of Outlook and Windows.