OST To PST Converter is the most efficient and secure software that is capable of converting OST files to PST formats. With the help of this tool, you can also convert OST files to different files or folders and several email clients. Moreover, the utility is fully loaded with highly advanced features considering the requirements of high-tech users. It maintains the folder hierarchy throughout the conversions process. You can try the full-featured trial versions of the software to analyze the performance. 
However, if you want to read your OST file Without outlook then here is the best article Open OST File Without Outlook. This article will provide the most effective solution to accomplish the process. They also introduce a professional solution to help to backup and migrate OST files.