How to Open an MPP File (With or Without Microsoft Project)

You can open a Microsoft Project .mpp file without owning Microsoft Project. Onplana Schedule is a free MPP viewer and editor for Windows and Mac: it opens the file, draws the full Gantt with critical path and float, and lets you edit the plan.

That is the whole answer, and the rest of this post is the detail: which free option fits what you need to do with the file, how to do it on a Mac, why Excel is not the route people expect, and what happens to the file when you open it. If you only need to look at a schedule once, a free, read-only Schedule Health Check reads it in the browser in under a minute with nothing to install. The alternative has a real price tag: Microsoft's own pricing lists Planner and Project Plan 3, the tier that includes the desktop Project client, at $30 per user per month, just to open a file someone else built.

In short. You do not need a Microsoft Project licence to open a .mpp file. Download Onplana Schedule, free for Windows and Mac, and open the file: full Gantt, critical path, float, editing, and a save back to Project XML that Microsoft Project reads. If you only need to read the file once and install nothing, upload it to the free Schedule Health Check instead. On privacy, what decides it is the contents of the file rather than its extension: Project XML is read on your own machine and nothing is uploaded, while everything else, a binary .mpp included, is converted on Onplana servers with the uploaded copy deleted within 24 hours.

Two free ways to open a .mpp file, and which one you need

What you actually need to do with the file decides which tool is right:

1. You need to keep working on it. You're taking over a schedule, correcting it, or building on it. Use Onplana Schedule, free for Windows and Mac: it opens the file on your desktop, lets you edit the Gantt and the grid, and saves the result as Project XML, which the original owner's Microsoft Project still opens. It reads .mpp, .mpx and Project XML, and also Primavera P6 .xer, ProjectLibre .pod and GanttProject .gan files.
2. You just need to look at it once. Someone sent you a schedule and you need to check dates, dependencies, or whether the plan is realistic before a meeting, and you would rather not install anything. Use the Schedule Health Check: upload the file, get a per-finding breakdown back in under a minute, and close the tab.

Schedule Health Check vs Onplana Schedule, side by side

What happens to your file when you open it

The privacy answer is different depending on which file format you're holding. A binary .mpp file has to be converted before either tool can read it: that conversion happens on Onplana's servers, and the converted copy is deleted within 24 hours. If the schedule was exported as MSPDI XML instead (File → Save As → XML, inside Microsoft Project), Onplana Schedule reads it directly on your machine and that file never leaves the desktop at all. What decides this is the contents of the file rather than its extension: Microsoft Project XML gets read locally, and a Primavera P6 or Planner XML export is an .xml too but is converted on the server exactly like a binary .mpp. If keeping the file entirely local matters more than convenience, ask whoever sent it for the XML export rather than the binary .mpp.

Opening and editing the file in Onplana Schedule, step by step

1. Download Onplana Schedule and install it. The same page carries the Windows and the Mac build. It is free and needs no Microsoft Project licence. It runs on Windows 10 (version 1809) or later and on macOS 13 or later.
2. Open the file: file associations let you double-click it directly, or open it from inside the app. It reads .mpp, .mpx and Project XML, and also Primavera P6 .xer, ProjectLibre .pod and GanttProject .gan.
3. Review the Gantt and grid: name, duration, start, finish, predecessors, resources, percent complete, outline level, critical path, float, milestones, and baseline bars if the file carries them.
4. Edit what needs correcting. Every change (cells, insert, delete, indent, outdent, links dragged with type and lag, all eight constraint types) supports undo, and the schedule reschedules automatically as you go.
5. Save the result as Project XML, which opens cleanly in Microsoft Project for whoever sent the file to you. Two things worth knowing before you do: Schedule does not write the .mpp format itself, and it never overwrites what you started from. The save creates a new file beside the original, so the .mpp in your inbox stays exactly as it arrived.
6. Export a PDF (File, Export, Chart as PDF or picture) if you need to hand the plan to somebody who will not install anything, or the task table as CSV for a spreadsheet.
7. If you want the schedule working as a shared plan rather than a file passed around by email, use Publish to create the project in Onplana directly from the desktop app. Sharing an MS Project plan with the team this way walks through that step in full, including what the rest of the team can see once it's published.

If you have Microsoft Project

Double-click the file, or open it from File, Open inside Microsoft Project. The desktop application comes with Planner and Project Plan 3, or as a one-time Project 2024 licence, and what each option costs is set out side by side. If the only reason to buy a seat is to open files other people send you, Onplana Schedule does that for free, and its saves open in Microsoft Project for whoever sent the file.

How to open an MPP file on a Mac

Microsoft Project's desktop application runs on Windows, not macOS, which is why a .mpp file landing on a Mac has nothing to open it. Download Onplana Schedule instead, open the file, and you have the whole plan: the Gantt, the critical path, float, and the same editing as the Windows build. It is free, it does not ask for a Microsoft Project licence, and it needs macOS 13 or later on either Apple silicon or Intel. If you are weighing up the Mac options more broadly, Microsoft Project for Mac sets them side by side.

If you only need to read the file and would rather install nothing, the Schedule Health Check runs in the browser and works the same on macOS as anywhere else. It is read-only, so the moment you need to change a date or a link, the desktop app is the one to download.

How to open an MPP file in Excel

You cannot. Excel has no importer for the .mpp format, so renaming the file to .xlsx or forcing it open with Open With gets you either an error or a screen of binary noise. That is not Excel being awkward: .mpp is a binary format holding a dependency graph, not a grid of cells, and there is nothing sensible for a spreadsheet to map it onto.

What does work is two steps. Open the file in Onplana Schedule, then choose File, Export, Task table as CSV, and open that CSV in Excel: every task arrives as a row with its dates, duration and predecessors. If the person you are sending it to will not install anything, export a PDF from the same menu instead.

What is an MPP file?

.mpp is the file format Microsoft Project saves a plan in. One file carries the whole schedule: tasks and their outline structure, durations, start and finish dates, dependencies with their type and lag, constraints, resources and assignments. It is binary rather than text, which is why a text editor or a spreadsheet shows nothing useful when you open one, and why reading it needs a tool that understands the format. The full explanation of the MPP format covers the version history and what each one holds.

When you still need Microsoft Project itself

Onplana Schedule is not a full replacement for every Microsoft Project workflow, and it's worth saying where it stops. If your organization runs Project Online or Project Server with enterprise resource pools, enterprise custom fields defined centrally on that server, or macros built in VBA, those depend on the server or the desktop client directly and won't travel through a .mpp file on their own. For the common case, someone emailed you a schedule and you need to read it, correct it, or hand it back, opening it without a Microsoft Project license is the faster and cheaper path both ways. If you need a tool to keep working in rather than one file to read, a free Microsoft Project alternative to work in every day is a different choice, and that list says where each one stops.

The diagram below shows the decision in one branch: what you need to do with the file determines which free option to use, and the privacy handling depends on the file format you start with.

Related reading: 7 hidden killers in your MS Project schedule covers what to actually look for once the file is open, MSPDI XML explained walks through what the XML export format contains if you want the fully local path, and importing the schedule without losing dependencies covers the checks worth running once you're bringing the file into a shared project rather than just opening it to look.

Run the free Schedule Health Check Upload your .mpp or MSPDI XML file and get a per-finding breakdown of dependency issues, constraint conflicts, dangling tasks, and the real critical path, computed from the dependency graph. No signup, no credit card. → Run the Schedule Health Check

Microsoft Project Online™ is a trademark of Microsoft Corporation. Onplana is not affiliated with Microsoft.