What is the MM file format?
.mm is the native file format of FreeMind, an open-source Java mind-mapping application first released in 2000. The file stores a mind map - a tree-structured diagram of interconnected ideas - as plain, uncompressed .xml, making it readable in any text editor without special software.
The root element of a .mm file is <map version="...">, which contains nested <node> elements forming the topic tree. Each <node> carries attributes for its label (TEXT), unique identifier (ID), fold state, and branch position. Child elements add rich content: <richcontent> for formatted notes, <icon> for symbol markers, <arrowlink> for cross-links between nodes, and <attribute> for key-value metadata.
Because FreeMind has been essentially unmaintained since 2014, its community fork Freeplane (released 2009) is now the recommended tool for working with .mm files. Freeplane reads and writes the same .mm extension using a compatible but extended schema. Other mind-mapping applications - including XMind and MindManager - can import .mm files.
The .mm format is distinct from compressed alternatives such as .xmind: it uses no ZIP wrapper, so the entire map is one human-readable XML text file. Maps range from a few kilobytes for a simple brainstorm to several megabytes for large projects with embedded notes.
Security & safety
RISK: LOWA .mm file is plain XML text and cannot execute code - opening it is safe. No scripting, macros, or embedded executables are possible in the FreeMind/Freeplane format. The only caution is that node notes use an HTML subset (richcontent), but this is rendered inside the application sandbox, not in a browser. Get .mm files from trusted sources as you would any document.
Format details
in a nutshell- Objective-C++ Source File (Apple Xcode) - Xcode uses .mm for Objective-C++ mixed-language source files; completely unrelated to mind maps - a developer file, not a document.
- Maya Movie File - Autodesk Maya uses .mm for rendered movie preview clips; a proprietary video format entirely unrelated to mind maps.
Programs that open MM files
Windows4 apps
Freeplane
Open-source Install Freeplane; double-click the .mm file to open and edit the mind map. The recommended FreeMind successor with full .mm compatibility.
FreeMind
Open-source File > Open to load the .mm file. Note: FreeMind is unmaintained since 2014; Freeplane is preferred for new installs.
Notepad / VS Code
Built-in Open the .mm as plain text/XML to inspect the node structure directly. Useful for debugging or scripting. 
macOS2 apps
Linux1 app
Freeplane
Open-source Install via package manager (freeplane) or download the AppImage; open the .mm file.
Miro / MindMeister (import)
Freemium MindMeister can import FreeMind .mm files via File > Import to view and edit in the browser. Technical details
deep spec| File encoding | Plain XML text, UTF-8 |
| Root element | <map version="X.X.X"> - version attribute refers to the FreeMind format version, not the application version |
| Binary signature | None - starts with optional <?xml declaration followed by <map version= |
| Node structure | Nested <node> elements forming a tree; key attributes: TEXT (label), ID (unique identifier), POSITION (left/right of root), FOLDED (collapsed state) |
| Rich notes | Formatted HTML notes stored in <richcontent TYPE="NOTE"> child elements |
| Cross-links | Inter-node arrows stored as <arrowlink> elements with DESTINATION attribute referencing target node ID |
| Icons | Named icons attached via <icon BUILTIN="..."> child elements |
| Custom attributes | Key-value metadata via <attribute NAME="..." VALUE="..."> child elements |
| Compression | None - uncompressed plain XML (unlike .xmind or .mmap which use ZIP containers) |
| MIME type | application/x-freemind |
| Format versions | 0.7.1, 0.8.0, 0.8.1, 0.9.0, 1.0.0/1.0.1 (FreeMind); 1.0.20+ (Freeplane extended fork, still .mm extension) |
| Typical file size | A few KB (simple map) to several MB (large map with many nodes and embedded notes) |
| Freeplane compatibility | Freeplane (active community fork, 2009-present) reads and writes .mm with a compatible extended schema; backward-compatible with FreeMind files |
| Released | 2000 (FreeMind 0.1; Java-based mind-mapping app) |
| Latest version | FreeMind 1.0.1 (2014); format schema stable since version 0.9.0 |
| Open standard | Yes · royalty-free |
| Specification | freemind.sourceforge.io |
MM conversions
Community Q&A
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