Some packages have a built-in capability to import and export to other types of mind mapping software. Some can only be made to talk to other software if someone decides to make an XSLT or other translation enabler. Many software authors have kindly provided information about the format of their mind map or interchange files to facilitate this.

Each software product has its own page. Click the blue i button to visit the page. The basis for selecting software to appear here is the availability of schema, file-format or interoperability information. Authors of some software did not reply to me, others had nothing available at the time. When I get new information I'll add it in...
 
Please let me know about any mistakes you spot or anything you can add: roygrubb [at] the above domain.