There is only one file type that uses the .XMIND extension:
XMind Workbook File
An XMIND file contains a workbook created by XMind, a brainstorming and mind mapping application. It may store multiple sheets, each with a diagram that captures ideas during a brainstorming session. XMIND files may also be used for storing organizational charts, work schemes, Gantt charts, and other individual and business diagrams.
Before XMIND files, XMind created .XMAP files to save workbooks. However, XMind replaced XMAP files with XMIND files, which are saved in the XMind Workbook format and supported by the XMind and Seavus iMindQ applications.
Since XMIND files are compressed with Zip compression, they can be decompressed using a Zip decompression program, such as Corel WinZip, 7-Zip, WinRAR, or Apple Archive Utility. Simply rename the .xmind extension to .zip and decompress it. You can then manually extract the contents of the XMIND file, which typically include multiple .XML files and .JPG thumbnail files. When you are finished viewing or modifying the contents, you can compress the archive again with Zip compression again using a Zip utility, then rename the .zip extension to .xmind.
Updated: September 5, 2018