A free app for Android, by IJP.

Chat Helper for WhatsApp is a useful application for WhatsApp users. It will help you to manage your chats better. You can use it as a widget on your home screen and you will always be able to see the number of unread messages for all your contacts. You can also add people to a group, and you will always be able to see the number of unread messages for all the people in that group. If you are on a chat with someone, you can click on the widget and you will see the person’s name and the number of unread messages.