Cloudflare's 1.1.1.1 DNS service exposes a CORS-enabled JSON API, and Simon Willison used that fact to build a browser-based DNS lookup tool, no server required.
The tool queries all three Cloudflare resolvers in parallel: 1.1.1.1 (standard), 1.1.1.2 (malware blocking), and 1.1.1.3 (malware plus adult content blocking). Willison had Claude Code build the UI, documented in pull request 258 on his tools repo.
The build log in that PR is worth reading. It shows exactly how a working dev uses an AI coding agent to ship a small utility fast, and what the handoff between human intent and machine execution actually looks like in practice.
[READ ORIGINAL →]