Pack your project onto one page…

A one-page Gantt chart headed "Plan on a Page | Sample Programme", with
                tasks for two projects laid out in swimlanes across a 2026–2028 timeline,
                plus milestone diamonds and Today and Deadline markers.

Edit the underlying data via the interface…

The Compact Gantt Windows app on its Data tab: a table of tasks grouped by
                swimlane showing id, name, start and finish dates, with an inspector panel
                on the right for editing the selected task.

Or edit the data, directly, in the spreadsheet…

An Excel worksheet of the same project data — one row per task, with columns
                for ID, swimlane, row, name, dates, label placement and fill colour, and
                sheet tabs for Tasks, Swimlanes, Links, Pipes, Curtains and Notes.

Runs as a portable Windows application (.exe).