The <a href="https://claude.ai/" rel="nofollow">https://claude.ai/</a> UI can now build and then render on-demand web apps - here's what Simon Willison got when he prompted "Build me a web app that teaches me about mandelbrot fractals, with interactive widgets": <a href="https://fedi.simonwillison.net/@simon/112650324117263516" rel="nofollow">https://fedi.simonwillison.net/@simon/112650324117263516</a><p>The 'artifacts' system prompt in the linked Twitter thread is what it uses to do that. Crazy stuff!