OST to PST Converter is one of the best approaches to converting OST into PST for Outlook 2019, 2016, 2013, 2010, 2007, and 2003. This software supports the OST files of all versions without any issues. Evidently, it is simple software that converts OST files to PST files in a matter of clicks without the need for Outlook installation. This software also converts your OST files using free methods.
To use the methods, you can visit: https://www.datarepairtools.com/blog/free-methods-to-convert-ost-to-pst-file/
Convert OST to PST using free Methods
You can make use of OST to PST Converter which is completely and able to migrate unlimited OST files to PST at once. The utility is safe and simple to use. Anyone can operate the solution and perform the conversion without data loss. Moreover, it is equipped with many amazing features that users can utilize as per necessary to migrate OST to PST. However, OST Converter has a Windows version as well if you are a Windows user and want to migrate OST to PST on Windows. You can use the freeware version of the tool and migrate first few files from OST folder to PST free of cost. Refer:- https://www.softakensoftware.com/ost-to-pst-converter.html
You can convert OST to PST using free manual methods like using Outlook Import/Export Wizard and by dragging OST mailbox items to a new PST file. However, these methods require Outlook and cannot work if the OST file is orphaned or corrupted. For a more reliable solution try DataVare OST to PST Converter Expert. It easily converts OST files to PST format with no data loss. It supports all Outlook versions and maintains folder structure. Perfect if you are dealing with inaccessible or large OST files. No technical skills required.
If you want to convert your OST file to the PST format without installing the Outlook app, then this is not possible manually. You must use GainTools OST to PST Converter tool which enables you to convert all OST emails at once to PST file format. It does not require the Outlook installation on the system to perform the operation. Refer: https://www.gaintools.com/ost/pst/