How to convert OST file in PST? Get the download professional OST Converter software that helps you to convert unlimited Outlook OST file to PST file format in Outlook 2021, 2019, 2016, and other below versions. It has a very simple GUI, everyone can easily understand how to convert OST file in PST without any help. During the process, the software keeps all the folder structures without any changes and data loss. There is no file size limitation, one can export large size of OST files into PST file format without Outlook. It allows you to batch save multiple OST data file to PST format without any data loss. It was compatible with all the editions of MS Windows OS including Windows 11 and Mac OS. You can also use the free demo version of the software without any cost.