Simon Willison’s Weblog

How Anthropic built Artifacts. Gergely Orosz interviews five members of Anthropic about how they built Artifacts on top of Claude with a small team in just three months.

The initial prototype used Streamlit, and the biggest challenge was building a robust sandbox to run the LLM-generated code in:

We use iFrame sandboxes with full-site process isolation. This approach has gotten robust over the years. This protects users' main Claude.ai browsing session from malicious artifacts. We also use strict Content Security Policies (CSPs) to enforce limited and controlled network access.

Artifacts were launched in general availability yesterday - previously you had to turn them on as a preview feature. Alex Albert has a 14 minute demo video up on Twitter showing the different forms of content they can create, including interactive HTML apps, Markdown, HTML, SVG, Mermaid diagrams and React Components.