We all have heard about the big successes of CHATGPT, currently (April 2023) with GPT-4.
Here are the links for CHATGPT:
To chat:
General information:
For developers:

But, there are other competitors as well.
Have a look at YOU.COM

The main advantage of is, that it works as normal search engine like Google.
However, you can chat with it and it will display the sources too: one of the main critical points of CHATGPT.

For developers: