2Do

2Do is the configurable one. Lists, tags, projects, checklists, saved searches that become smart lists, and a quick-entry box that understands dates — you can build almost any system inside it, which is why people who bounced off Things for being too opinionated and off OmniFocus for being too strict tend to land here.

Buy it from 2doapp.com. That sentence matters more than anything else on this page, because the Mac App Store listing for the same app is now subscription-only at $4.99 a month or $39.99 a year, and it is the listing most people find first. The direct licence is $49.99 once, and the developer's own documentation calls it a perpetual licence rather than a rental.

The boundary sits at eighteen months. That is how long free updates run from the date you buy. After it passes the app keeps working and keeps syncing; you simply stop receiving new versions unless you take the discounted renewal. Think of it as a paid-upgrade app on an eighteen-month clock, not as a purchase that ends the question forever.

Sync goes through Dropbox, CalDAV, iCloud or Apple Reminders — your accounts, no vendor service in the middle. The iPhone and iPad apps are bought separately.

If your list is twenty things and some repeating chores, this is more machinery than you need. 2Do starts paying off when you have several contexts that must not bleed into each other.