What is the MCR file format?
An .mcr file is a MAXScript MacroScript for Autodesk 3ds Max - a plain-text script that 3ds Max registers directly into its user interface as a toolbar button, menu item, or keyboard shortcut. Unlike generic .ms MAXScript files that run on demand, .mcr files carry a structured header declaring the script’s name, category, tooltip, and optional icon, which allows 3ds Max to expose them in the Customize User Interface dialog.
The file is written in MAXScript, the built-in scripting language of 3ds Max, and begins with a macroscript declaration block followed by handler functions. The on execute do handler defines what happens when the button is pressed; additional handlers such as on isEnabled do control UI state. .mcr files are stored by default in %AppData%\Autodesk\3ds Max <version>\ENU\UI\UserMacros\.
Common uses include:
- custom modelling, rigging, or rendering automation tools,
- pipeline utilities for exporting or batch-processing scenes,
- UI shortcuts wrapping complex multi-step MAXScript workflows.
The format has remained essentially unchanged since MAXScript was introduced with 3ds Max 1.0 around 1996. Files can be viewed and edited in any text editor such as Notepad++ or Visual Studio Code.
Note: BricsCAD also uses the .mcr extension for its own macro recorder files, which are an entirely separate, incompatible format.
Security & safety
RISK: MEDIUMMCR files contain executable MAXScript code that runs inside 3ds Max. A malicious .mcr could access the file system or run shell commands via MAXScript's ShellLaunch/DOSCommand functions. Only run MCR files from trusted sources (official Autodesk Exchange, ScriptSpot with community ratings). Do not run MCR files found in unsolicited emails or downloads.
Format details
in a nutshell- BricsCAD Macro File - Bricsys BricsCAD saves keyboard/command macros as .mcr; format is incompatible with 3ds Max MCR and contains BricsCAD-specific VBA-like syntax.
- MATLAB Compiled Program (legacy) - Older MATLAB versions used .mcr for compiled runtime packages (MATLAB Compiler Runtime); largely replaced by .ctf and installer-based deployment.
Programs that open MCR files
Windows4 apps
Autodesk 3ds Max
Paid MAXScript menu > Run Script, select the .mcr; then Customize > Customize User Interface to assign to toolbar/hotkey.
Notepad++ (view/edit source)
Open-source Open as plain text; syntax highlighting available via MAXScript language file.
Visual Studio Code (view/edit source)
Open-source Open as plain text; MAXScript extension available in marketplace for syntax highlighting. Technical details
deep spec| Format type | Plain-text MAXScript source file |
| Encoding | ASCII / UTF-8 text |
| Key header keyword | `macroscript` declaration block (name, category, tooltip, optional icon) |
| Scripting language | MAXScript - Autodesk 3ds Max built-in scripting language |
| Magic bytes | None (text file; identifiable by `macroscript` keyword near the start) |
| Typical file size | 1 KB - 200 KB |
| Default storage path | `%AppData%\Autodesk\3ds Max <version>\ENU\UI\UserMacros\` |
| UI integration | Category and tooltip metadata exposes the script in Customize User Interface > Toolbars/Menus/Quad Menus |
| Common handlers | `on execute do`, `on isEnabled do`, `on isChecked do` |
| Platform | Windows only (3ds Max is Windows-only) |
| Related formats | `.ms` (generic MAXScript), `.mse` (encrypted MAXScript), `.mzp` (MAXScript zip package) |
| MIME type | application/octet-stream (commonly treated as text/plain) |
| Released | circa 1996 (3ds Max 1.0 with MAXScript) |
| Latest version | N/A (format unchanged; MAXScript version follows 3ds Max) |
| Specification | help.autodesk.com |
MCR conversions
Community Q&A
asked by usersNo questions yet - be the first to ask about MCR files.
