Aptus 1.0 for Mac was available to download from the developer's website when we last checked. We cannot confirm if there is a free download of this app available. This software for Mac OS X is an intellectual property of Moople apps. We recommend checking the downloaded files with any free antivirus. The software belongs to Developer Tools.
From the developer:
Aptus is a dedicated browser that lets you preview, edit and screenshot your responsive site at any size from mobile through to large desktop.
Focus your responsive workflow with a tool that doesn’t rely on bookmarklets, restrictive pre-defined breakpoints - or even a web connection.
Aptus improves on web-based tools by letting you create and work on multiple breakpoints simultaneously, even setting custom user agents if required.
You may want to check out more software for Mac, such as Multisite for iWeb, HyperEdit or Validator-SAC, which might be related to Aptus.