Aeon Timeline Continuity checking in complex or multi-POV series. $65 USD one-time; additional year of updates $35/yr
Plottr Plotting a book or series on a visual timeline before drafting. Plottr $60/yr, Plottr Pro $99/yr or $9.99/mo, Pro + Community $129/yr or $14.99/mo; lifetime $150 / $599 / $649