What is the MPP file format?
.mpp files contain data stored with Microsoft Project, a specialised software for managing projects developed by Microsoft. Within .mpp files, users can find such data as a time axis, list of tasks, resource allocations, and other information about a project - making them a valuable support for project managers.
Internally, .mpp is a proprietary binary format built on the OLE2 Compound File Binary container, the same underlying container used by legacy .doc and .xls files. The file is identified by its internal Project streams rather than by the shared D0 CF 11 E0 A1 B1 1A E1 header alone. The format has evolved through several generations since its introduction in 1990, with distinct binary layouts for Project 2003, 2007, 2010, and later releases.
.mpp files, generated with MS Project, can be used within project teams in order to:
- Manage task assignment and dependencies (including Gantt charts and critical-path analysis),
- Track and report progress,
- Control finances and budgets,
- Create schedules with milestones, baselines, and resource calendars.
.mpp project files can be updated by different members of a given team. In order to minimise the risk of unauthorised access, access privileges and blockades of specific information within the files can be defined.
In order to provide maximum compatibility of changes introduced by different members of a team working on a project, it is advised to use the same version of Microsoft Project across the team. Using different versions of Microsoft Project may cause problems with properly reading modifications introduced by other users, since each generation uses a distinct binary layout.
For cross-platform and cross-version exchange, Microsoft Project can export to the MSPDI .xml format or to the older .mpx interchange format. Template files carry the .mpt extension. Third-party tools such as ProjectLibre and MOOS Project Viewer can open .mpp files on macOS and Linux without a Microsoft Project licence.
Security & safety
RISK: LOWAn MPP is passive schedule data, but it lives in the OLE2 compound-document container that CAN carry VBA macros (Project supports macros). Treat an MPP from an unknown sender like any Office file: don't enable macros unless you trust the source. Read-only viewers (MOOS Project Viewer, Project Plan 365 viewer) don't run project macros and are the safe way to inspect a plan. Otherwise the only practical issue is version compatibility, not malware.
Format details
in a nutshell- CAM toolpath file (.mpp) - A machining/toolpath file used by CAD/CAM systems such as Mastercam and CADdy++.
- Music Publisher score (.mpp) - A sheet-music document created by the Music Publisher notation program.
Programs that open MPP files
Windows4 apps
Microsoft Project
Paid The native editor - File > Open. Sold separately from Office/365 (desktop or Project Online/Plan). 
MOOS Project Viewer
Freemium Open the .mpp to view Gantt/task/resource views and print; read-only. Java-based, runs anywhere. (Free viewing tier.) 
ProjectLibre
Open-source Free desktop MS Project alternative - File > Open many .mpp files to view and edit; successor to OpenProj.
Project Plan 365 (viewer)
Freemium Open and view .mpp (free viewer mode); paid mode edits. By KaDonk/Housatonic - replaces their older 'Project Viewer'/'LiveProject'. 
macOS3 apps
ProjectLibre
Open-source Free, runs on macOS via Java - open .mpp to view/edit (MS Project has no native Mac version). 
Linux2 apps
Project Plan 365 (online) / ProjectManager.com import
Freemium Upload/open an .mpp in the browser to view the schedule; some tools import MPP into an online plan. Technical details
deep spec| Container format | OLE2 Compound File Binary (CFB); same underlying container as legacy `.doc` and `.xls` files |
| File signature (magic bytes) | `D0 CF 11 E0 A1 B1 1A E1` at byte offset 0; format is distinguished by its internal `MSProject` stream, not the shared header alone |
| MIME type | `application/vnd.ms-project` |
| Template extension | `.mpt` (Microsoft Project Template) - stores reusable project structures without task-specific data |
| Binary format generations | Distinct layouts for Project 98, 2000, 2003, 2007, 2010, 2013-2016, and 2019/2021/365 |
| Scheduling engine | Critical Path Method (CPM) for auto-scheduled tasks; manual scheduling mode introduced in Project 2010 |
| Data stored | Tasks, resources, assignments, calendars, Gantt chart layouts, dependency types (finish-to-start etc.), cost and budget fields |
| Baseline snapshots | Up to 11 baselines per plan (Baseline through Baseline 10) for schedule progress tracking |
| Export / interchange formats | MSPDI (`.xml`), legacy `.mpx`, `.csv`, `.xlsx`, PDF |
| Compression | None - raw binary OLE2 streams with no built-in compression |
| Third-party read support | ProjectLibre, MOOS Project Viewer, and Project Plan 365 can open `.mpp` on Windows, macOS, and Linux |
| Developer | Microsoft Corporation |
| License / openness | Proprietary closed format; Microsoft has published partial documentation via the Open Specifications programme |
| Default view embedded | Gantt Chart with linked task table and timescale; view and column settings are stored inside the file |
| Released | 1990 (Microsoft Project for Windows); format evolved through 2003/2007/2010+ |
| Specification | learn.microsoft.com |
MPP conversions
Community Q&A
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