ChatGPT has just opened their API for programmers.
You can use it to create a Chatbot for your website, in the style you prefer.
You can try Chatbase, to build the Chat easily, they have a freeplan.
Further you can use it to build applications and integrate them into your website or applications.
Learn more about ChatGPT API here:
https://openai.com/blog/introducing-chatgpt-and-whisper-apis