This is part of my ChatGPT / OpenAI toolsuite. These are small applications ranging from toys to workhorses, and you're welcome to have fun with it, and I even more welcome feedback and fresh ideas for improvements. Contact me here. The sources for these are in my chatGPTtools project; here is a list of the tools.
When editing in textareas, you can often submit with enter, and insert a newline with shift+enter. Hover over the buttons / input fields to see tooltips with more information. The import / export field admits either complete JSON requests for the chat completion API, or just the list of messages. By setting "n" to a higher value you can check out the range of answers you'd get from the API in one go. "Retry" will remove the last answer(s) and try again. There are a number of system prompts to select, though most of them are mostly for fun.
You'll need your own ChatGPT API key to run that, which you can get at https://platform.openai.com/. After logging in there with your ChatGPT credentials, you can create an API key in the profile settings (top right corner) at "View API keys".