The .mpp file
The planner's live document, in Microsoft's own binary format. It holds the plan as it is being worked on, and it changes whenever they save. Reading it faithfully means owning the program that writes it.
.mpp or .xml
You were sent an .mpp file.
It is the planner's working file. The export is the one to ask for.
An .mpp file is Microsoft Project's own working format, and
opening it reliably takes Microsoft Project. The same plan saved as XML is a published
snapshot that other programs can read, and Project writes it in two clicks.
Two files, one plan
The XML export
The same plan written to Microsoft's published interchange schema: tasks, dates, dependencies, baselines, resources and notes, as text. A snapshot of one version, at the moment the planner chose to publish it.
Ocean Plan Viewer reads the export. That is why it needs no licence.
What to ask for
Send the planner this
Could you send me the plan as XML rather than
.mpp? In Project it is File → Save As, then XML Format (*.xml) as the file type. It takes a moment and I can read it without a Project licence.In a German Project: Datei → Speichern unter, file type XML-Format (*.xml).
Then open it
Download the viewer, double-click it, and drag the XML onto the window. Nothing is installed and the file is never written to.
Why the export can be read and the working file cannot
Both questions have the same answer, and it is also the reason this program installs nothing.
One is private, one is publishedA working format serves the program that owns it. An interchange format exists to be read by something else.
Text, not a binary documentThe export is XML. Reading it needs a parser, not a reimplementation of Microsoft Project.
A snapshot, not a live fileThe planner decides what is published and when. Everyone reading it is reading the same version.
Nothing to installBecause there is no proprietary format to support, there is no runtime, no installer and no administrator to ask.
Project 2013 exports onwards are what the viewer is tested against. What the viewer shows →
Why we built this project viewer
Ocean Consulting GmbH has worked on banking data warehouses, mobile-operator migrations and datacenter moves since 1999, writing the plans and steering the teams that worked to them. The viewer was built in 2018 on one of those projects, because half the team could not open the plan they were working to.