WindowsWhat is the MZP file format?
An .mzp file is a ZIP archive renamed with the .mzp extension for use as an installable plugin or script package for Autodesk 3ds Max. The format was introduced around 2003 as the standard distribution unit for MAXScript plugins, tools, and utilities.
The archive must contain a file named .run - a MAXScript source file. When a user drags an .mzp file directly into the 3ds Max viewport, the application detects the extension, extracts the archive to a temporary location, and automatically executes the .run script via fileIn. That script handles the actual installation - copying files to the right directories, registering menu items, and setting up the plugin. Beyond the mandatory .run file, an .mzp package may include .ms (MAXScript source), .mse (encrypted MAXScript), .msl (library), .msu (utility), .mxi (plugin descriptor), and any supporting assets such as textures or icons.
Because .mzp is a standard ZIP file with a renamed extension, it can be opened and inspected by any archive tool - renaming it to .zip and opening it in 7-Zip or WinRAR reveals all contents. This is useful for examining what an installer will do before running it.
The format remains current as of 3ds Max 2025 and no replacement has been introduced. .mzp packages are distributed via Autodesk's Script Spotlight, scriptspot.com, and individual developer sites.
Security & safety
RISK: MEDIUMMZP files execute MAXScript code automatically on drag-and-drop into 3ds Max - only install from trusted sources (Autodesk App Store, ScriptSpot with good reviews). Before installing, rename to .zip and read the .run and .ms files to audit the code. MAXScript can write files to disk and launch external processes.
Format details
in a nutshellPrograms that open MZP files
Technical details
deep spec| Container format | Standard ZIP archive (magic bytes 50 4B 03 04); renamed to .mzp |
| Compression | DEFLATE per entry (standard ZIP deflate compression) |
| Mandatory entry | .run file (MAXScript source); 3ds Max executes this via fileIn on drag-and-drop install |
| Install mechanism | Drag into 3ds Max viewport - application detects .mzp extension, extracts archive, and runs the .run script automatically |
| Script formats inside | .ms (MAXScript), .mse (encrypted MAXScript), .msl (library), .msu (utility), .mxi (plugin descriptor) |
| Integrity check | ZIP CRC-32 per archive entry |
| Max archive entries | 65,535 (ZIP specification limit) |
| Platform | Windows only (3ds Max is Windows-exclusive) |
| Manual extraction | Rename .mzp to .zip to inspect or extract with any ZIP-compatible tool (7-Zip, WinRAR, Windows Explorer) |
| Typical file size | 10 KB - 20 MB; script-only packages are small; larger ones include texture or model assets |
| MIME type | application/zip (identical to standard ZIP) |
| Format status | Current as of 3ds Max 2025; no replacement format introduced |
| Released | 2003 (introduced in 3ds Max with MAXScript) |
| Latest version | N/A (format unchanged; ZIP-compliant) |
| Specification | help.autodesk.com |
MZP conversions
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