Whatsapp Messenger come with lot of amazing features but if we talk about privacy or security. Then there is no such feature in Whatsapp. You can not lock or password protect your Whatsapp. As such there are many security locks in Android like pattern or pin lock. But if we want to lock only Whatsapp Messenger then here is the method to Set Password or Lock on Whatsapp Messenger
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Amazing WhatsApp Tips And Tricks
There are many aps available on market to password protect your Whatsapp depending upon your  mobile platform.

Whatsapp Lock For Android Phone

App: Block for WhatsApp protect msg

The best thing about this app is if someone try to unlock your phone using wrong password and if your phone has front camera. it will take a picture of the intruder and saved in the photo gallery.

When you install this app it ask you for a 4 pin password.  And you can also set the auto lock time in this app.

App to Lock Whatsapp on BlackBerry

Using this app you can set lock on your Whatsapp messenger on your Blackberry device. It is freely available on BlackBerry World you can download and install it from the above link.

App to Lock Whatsapp on Nokia Asha Phone

It is always require to lock private apps like Whatsapp, and is good to secure and keep your privacy. Using this app you can easily set password on any private app on your Nokia Asha. 

How to Lock Whatsapp in Windows Phone 

Windows phone does not have any app to lock whatsapp. I am searching for some good app, i will update this post.

Lock Whatsapp on Iphone

 As such there are many apps to lock whatsapp on iphone. But none of them work perfectly. So i will not suggest those apps to you. I will update when i got the right app.

Here i have found and post the best apps to lock Whatsapp on your Android, BlackBerry, Nokia Asha, Windows Phone  and Iphone. All these apps are tested and work fine.