Do you want to combine multiple PST files into one PST? The best program is ToolsGround Merge Outlook PST Tool, which I recommend. This easy-to-use program is safe and simple to use. PST files from Outlook can be combined into a single file. No technical knowledge is needed to utilize the software because it is easy to use. Operating Systems: With Windows 11, 10, 8.1, 8, 7, Vista, XP, and earlier versions, the program is completely compatible. You can test the program's features and capabilities with the free demo version.