Most people think that it is 100% impossible to send android apps on whatsapp but through my research i came across a trick to send android apps on whatsapp you dont need Dropbox or any third party apps to do that
kindly follow the steps below

STEPS ON HOW TO SEND APK ON WHATSAPP

1. Frist locate the app you want to send
2. Get the apk of the app by searching it on your file manager if you didn't find it you need to backup the app
NOTE apk format is like this yourapp.apk

3 After successful backup go back to your file manager and search for the app again you will see the app
4 Rename the app to yourapp.txt
5 After that go to your whatsapp click on the share button then click on document
6 Now search for your app ie the one you saved in this format yourapp.txt now send it
7 Now tell the person you sent it to that its should be renamed to yourapp.apk
8 After that he can successfully install the app

As Simple as that right?
Any question should be drooped in the comment box.
- See more at: http://www.jeftechcares.tk/2016/08/how-to-send-android-apps-on-whatsapp.html#sthash.NLQoWfAK.3BZYZHSA.dpuf