Bolt AI (https://boltai.dev/) generates designs for pages, websites, and applications from an instruction in HTML and css.

A chatbot is present to help the generations evolve.

Export the code by copy/paste, export the design in image and figma format.
Share by URL for feedback and collaboration.

Seems unlimited in free version (apparently the only one available despite the ads on the site).

Test for two variations of the same site: