GanttProject is a free, open-source desktop application focused entirely on scheduling. An official portable version can be placed directly on a USB drive.

"You are running an unauthorized copy. Your project data has been backed up to an external server. To unlock, send 0.5 Bitcoin."

If you are looking for a comprehensive, team-oriented alternative, OpenProject is a highly secure, open-source web application Best open source MS Project alternative - OpenProject .

: Full access to the desktop application (Microsoft Project Professional) and the online version.

Getting Started with Microsoft Project: Downloads, Trials, and Portable Alternatives

A lightweight, desktop tool that is perfect for quickly building schedules. It is easy to move between computers and is entirely free.