Downloading Kayero 0.2.3 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. This free software for Mac OS X is a product of Mathieu Dutour. The program lies within Developer Tools, more precisely Webmaster Tools. Please check the Mac app with an antivirus before launch as it is downloaded from the developer's website, and we cannot ensure that it is safe.
From the developer:
Kayero is an interactive JavaScript notebooks editor. The Kayero notebook is a Markdown document with a script attached. Every notebook is fully editable and can be saved as a Markdown file. JavaScript code blocks can be executed. The code blocks can be set to run automatically when the notebook loads. They can also be set to hidden, so that only the result is visible.
You may want to check out more software for Mac, such as Url Extractor X, Boks or WebPics, which might be similar to Kayero.