WhatsFake - Make fake conversations that look just like WhatsApp
Intercom - Intercom is a customer relationship management and messaging tool for web businesses. Build relationships with users to create loyal customers.
SMS Class Tools - SMS Class Tools is a fake message generator that allows you to have some fun with your colleagues and friends.
Talkus - Chat with your website users from Slack
Fake Text Message by NeuronDigital - Fake Text Message is an app by NeuronDigital that allows users to send fake text messages to their other users as well as they can take screenshots of conversations to share them with friends and family members.
Chatlio - When you have a business to run, your average instant messaging software just will not do. You need an internal presence upon which your entire team can collaborate on. Read more about Chatlio.