If you're looking for a free tool to convert an Outlook OST file to PST, the GoldyTools OST to PST Converter is an excellent choice. This user-friendly software makes it easy and safe to import OST files into PST. Simply download and install the tool, run the program, and drag and drop your OST files into it. After selecting PST as the output format, you can start the conversion process. The tool also supports batch conversion, allowing you to convert multiple files at once. While the free version offers great functionality, it does limit the number of items you can convert per folder. Despite this, it provides a cost-effective way to manage your email data without spending a dime.