There is no doubt that WhatsApp is hands down the most used instant messaging service today and there's no messaging app that can match it in terms of users on-board.

But unfortunately, the app has called for a host of hacks that basically allows a person to spy on any of their friends or family via WhatsApp without them having any knowledge of it.

This new creepy app  "Chatwatch"  helps an individual to do  this is by making use of the online or offline status feature of WhatsApp's to tell users how often their friends check the app and also estimates as to when they go to bed every day -- potentially making it an invasive app.

"Find out when they went to bed, how long they slept… Even compare chat patterns between people you know, and we will tell you the probability of them talking to each other during the day, using Artificial Intelligence," Chatwatch notes on its website.

Now what’s more distressing is that all this comes at a time when Facebook users are busy uninstalling apps they got connected with long ago via "Facebook log-in" after the social media platform, which also owns WhatsApp, was hit by a major data breach.

“It's a creepy new trick that the app's developers hope will bring more attention to how Facebook handles our data, along with how other companies access and analyse it," tech website LifeHacker reported. "It's also likely that WhatsApp will find a way to block Chatwatch soon. So if you want to spy on your friends expose Facebook's privacy issues, you should try it soon," it added.

Chatwatch generally requires 24 hours before it can generate certain insights but even if you’ve disabled the ‘Last Seen’ feature in your account settings, it’ll still be able to figure out your WhatsApp activity quiet easily.

"Chatwatch" is currently available on Android platform and the developers are reportedly working on a web-based version as well. The app was first launched on iOS devices but it was later taken off from the Apple App Store. For reasons unknown to the website, it further adds that Apple has suspended their app from the app store, but they are working on a web version to launch as soon as possible, and appealing the decision with Apple.