Downloading Curio Reader 10.1 for Mac from the developer's website was possible when we last checked. We cannot confirm if there is a free download of this app available. The software lies within Productivity Tools, more precisely Office Tools. We recommend checking the downloaded files with any free antivirus. The actual developer of this free software for Mac is Zengobi, Inc.
From the developer:
Curio Reader is a note-taking, mind-mapping, brainstorming, and task management application. With Curio, users can create project notebooks filled with free-form idea space pages where they can intuitively gather, associate, and recall notes, ideas, and files related to a project or class.
You may want to check out more software for Mac, such as Read One, The Curio Society: Eclipse Over Mesina Collector's Edition or The Curio Society New Order CE, which might be similar to Curio Reader.