Free online SMMX to OPML converter

SimpleMind stores editable mind maps in SMMX, while many outline and feed applications accept OPML instead. Converting the file is useful when you need to move a map into an OPML-compatible editor, reader, or outlining tool.

What the SMMX format is

SMMX is the XML-based native file format used by SimpleMind for mind maps. It stores the map’s topic hierarchy and can also contain notes, labels, links, icons, relationships, formatting, and layout information. You typically encounter SMMX when exporting or synchronizing maps from SimpleMind on desktop or mobile devices.

What the OPML format is

OPML, commonly saved with the .opml extension, is an XML outline format. Its nested <outline> elements represent parent and child topics, making it suitable for outlining applications, note systems, feed readers, and software that imports hierarchical project information.

OPML is more portable than a proprietary mind-map file for transferring the map’s logical structure. It is not designed to preserve a mind map’s canvas layout, branch positions, colors, images, or other visual features.

How to convert SMMX to OPML

Using SimpleMind

1. Open the .smmx file in SimpleMind.
2. Choose File → Export or the application’s equivalent export command.
3. Select OPML or Outline/OPML as the output format.
4. Choose a destination, enter an .opml filename, and save the export.
5. Open the resulting file in the target application and check that parent-child relationships are correct.

The exact menu names depend on the SimpleMind edition and operating system. If OPML is not listed, export the map through SimpleMind’s outline or interchange options, or use the online converter on 101convert.com: select SMMX as the source format, upload the file, choose OPML, start the conversion, and download the generated .opml file without installing software.

Checking the converted file

Open the OPML file in a text editor or an OPML-compatible application. A valid file normally has an <opml version="2.0"> root element and nested <outline> elements for the map branches. If the destination application rejects the file, verify that the filename ends in .opml and that the file was not saved with an additional .txt extension.

Quality and compatibility limitations

The conversion normally preserves the hierarchical topic structure, but OPML cannot represent the full visual model of an SMMX map. Branch geometry, floating topics, colors, line styles, icons, images, boundaries, and canvas positioning can be discarded. Notes and hyperlinks may be retained as OPML attributes only when the converter maps them to fields supported by the destination application.

Review maps containing cross-links, summaries, or non-tree relationships after conversion: OPML is fundamentally a nested outline, so relationships that do not fit a single parent-child hierarchy may be flattened, omitted, or represented as ordinary text.