Intelligent personal assistant - Apple Siri. Microsoft Cortona. Google Now.

1.Siri

Sirius is an open end-to-end standalone speech and vision based intelligent personal assistant (IPA) similar to Apple’s Siri, Google’s Google Now, Microsoft’s Cortana, and Amazon’s Echo. Sirius implements the core functionalities of an IPA including speech recognition, image matching, natural language processing and a question-and-answer system. Sirius is developed by Clarity Lab at the University of Michigan. Sirius is published at the International Conference on Architectural Support for Programming Languages and Operating Systems (ASPLOS) 2015. 

2.Cortona

Cortana is an intelligent personal assistant created by Microsoft for Windows Phone 8.1 and Windows 10 (where it now supersedesBing Mobile), Microsoft Band, Windows 10, and coming to iOS, Android,and the Xbox One.

Cortana helps you stay on top of things, whether alerting you about a flight delay, reminding you to pick up something from the store or to leave early for work because of traffic delays.

3.google now

Google Now is an intelligent personal assistant developed by Google. Google Now is available within the Google Search mobile application for Android and iOS, as well as the Google Chrome web browser on personal computers. Google Now uses a natural language user interface to answer questions, make recommendations, and perform actions by delegating requests to a set of web services. Along with answering user-initiated queries, Google Now proactively delivers to users information that it predicts (based on their search habits) they may want. It was first included in Android 4.1 ("Jelly Bean"), which launched on July 9, 2012, and was first supported on the Galaxy Nexus smartphone. The service was made available for iOS on April 29, 2013 without most of its features. Google Now was released for Google Chrome on March 24, 2014.