What can open or identify an old .mpn file?

The extension has been associated with more than one type of file. It may come from Microsoft MapPoint, which used older geographic-data formats, or it could be a Mophun mobile-game file from early Sony Ericsson-era phones. It might also be proprietary data from a specific application, so the program or device that produced it is the most useful clue.

A file-identification utility such as TrID can compare the file’s binary signature against a large database of known formats. That should narrow down whether it is a MapPoint file, a Mophun file, or something less common. Make a backup first, since simply renaming the extension will not convert the data.

Start by checking the file’s contents rather than relying only on the extension. On Linux or macOS, run the `file` command against it; it examines the file signature and may identify the format. You can also open a copy in a hex editor or Notepad++ and inspect the first few bytes for a recognizable header.

If you know where the file came from—an old phone, mapping project, backup, or particular software—use that history to guide the search. There is no single standard meaning for `.mpn`, so identifying its source is usually more reliable than trying random programs.