pimatic is described as 'Home automation framework that runs on node.js'. There are four alternatives to pimatic for a variety of platforms, including Linux, Mac, Windows, Online / Web-based and Self-Hosted solutions. The best alternative is ioBroker, which is both free and Open Source. Other great apps like pimatic are FHEM (Free, Open Source), Conrad Connect (Free) and IP-Symcon (Paid).
ioBroker is an integration platform for the Internet of Things, focused on Smart home, Building Automation, Smart Metering, Ambient Assisted Living, Process Automation, Visualization and Data Logging. It aims to be a possible replacement or extension for software like f.e.
FHEM (TM) is a GPL'd perl server for house automation. It is used to automate some common tasks in the household like switching lamps / shutters / heating / etc. and to log events like temperature / humidity / power consumption.