I wish more things are released like that.
Also your tool might be very useful because there isn't a good Gantt tool that is lightweight anymore, i search for one recently and my only solution in the end was to use an excel template...
My 2 feedbacks if you are interested: - it is annoying to have the "category" required to create a task. Maybe you could create a task with an "undefined" category if none provided? - a great feature would be to be able to export the result output or view in a PNG picture or SVG.