ChatGPT-web is a simple one-page web interface to the OpenAI ChatGPT API. To use it, you need to register for an OpenAI API key first. OpenAI bills per token (usage-based), which means it is a lot cheaper than ChatGPT Plus, unless you use more than 10 million tokens per month. All messages are stored in your browser's local storage, so everything is private. You can also close the browser tab and come back later to continue the conversation.

As an alternative to OpenAI, you can also use Petals swarm as a free API option for open chat models like Llama 2.