We can suggest you 2 ways of building a chatbot for React.js. Here we go:
It is very easy to build a chatbot for React.js or other applications with the help of Back4App. You can simply register on this platform for free and then access the dashboard. After defining the model for your chatbot, you can select the ‘chatbot’ under ‘Webhosting + Custom domain’ settings. You can express the cloud code to perform further settings. Here is the complete guide to building a chatbot for React.js.
By the way, you will find these options under the ‘Database’ category available on the dashboard of Back4App.
On the other hand, Dialogflow which is a product of Google Cloud is another suitable option for building chatbots. The ‘Build chatbots with Dialogflow’ page of Google Developers can also aid you in this regard. Consider watching the following video for further details.