Mindmapping programs (XMind, Freemind etc.)

In general, mindmapping software arranges information in a tree structure, as NoteCase Pro does, too.
It just displays the information differently on screen.

Also, some features of linking information or attaching different types of files to notes etc. will probably differ between the mindmapping program of your choice and NoteCase Pro.
So if you exchange data between NoteCase Pro and a mindmapping program, don't expect 100% data compatibility.

That means, such data exchange is more a one-way thing than a "maintain a file with NoteCase Pro and with mindmapping alternatingly" except if you only work with textual information in your files, for example. Then a two-way data exchange may work even over time.

As of now, no mindmapping program supports NoteCase Pro's Natively Supported file Formats.
So you can only use export and import to exchange data.

First step is to find common supported file formats of NoteCase Pro and your mindmapping program.
NoteCase Pro has a large set of supported Export Formats and an even larger set of Import Formats.

Most mindmapping programs support the .opml Outline Processor Markup Language. So you may export from NoteCase Pro as OMPL.

If you use xMind, MindManager or MindMap/LX, then you can import into NoteCase Pro directly using their native file formats, as they are supported directly by NoteCase Pro as import formats.

Feel free to write your own import / export scripts. It is possible using the available NoteCase Pro scriptable program commands scriptable program commands to read / write note properties and note contents.

The NoteCase Pro team would be glad to add your import / export plugin to the feed of available plugins!