Build a chatbot on a free web service

Project specs: I'm building a network of websites and every website is supported by an "Assistant' (the chatbot). Need help building this chatbot on a service of your choice that has a visual composer and that I can use after, once this first one is set by you. - I will provide the script for the entire conversation. - You must use a FREE chatbot service of your choice for this. Tell me why this one is best than others.. - I will need to use the same chatbot on different websites with very little variations each - I will need to duplicate, edit and publish other hosted versions of this bot myself. I will need to own the account you create for me for this service. The service you choose must allow me to duplicate and edit bots. - This is NOT a Facebook messenger bot. It is for the web. - I will provide one Sketch file with design styles and script, and an Invision prototype with all interactions and outcomes defined. - You can extract all code from here - The dialog consists of about 4 questions with 2 pre-set answers each. User advances when clicking on one response and is linked to a URL on the other. - Experience must is responsive but design is ready to be the same for all breakpoints. This can easily be done on CSS/HTML but I don't code .. if you have a better way to do this experience in a way that is customizable from the front end so I can adjust dialogs and links, I'm totally open to hear your solution. The experience can be seen on the product prototype - please click: (What can I do?) button on homepage. [login to view URL] Dialog attached - narrative may change but structure is the same. Tell me why the service you chose is best than others.