We all have heard about the big successes of CHATGPT, currently (April 2023) with GPT-4.
Here are the links for CHATGPT:
To chat:
https://chat.openai.com
General information:
https://openai.com/
For developers:
https://beta.openai.com/docs/api-reference/
But, there are other competitors as well.
Have a look at YOU.COM https://you.com
The main advantage of you.com 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:
https://docs.you.com/using-an-api/getting-data