The 2.21 version of twodue for Mac was available as a free download on our website. The actual developer of this free software for Mac is Powersurgepub. The software relates to Lifestyle Tools.
From the developer:
Two Due is a powerful To Do List manager with many special features. It supports multiple lists, recurring To Do items, integration with your Web browser, and multiple category levels for each to do item.
Two Due stores its To Do lists in tab-delimited text files. This makes it easy for Two Due to support multiple lists.
You may want to check out more Mac applications, such as GHC Interactive System with Extensions, S90 ES Total Librarian or nemo440, which might be similar to twodue.