The article defines “HTML tools” as single-file HTML applications that bundle HTML, JavaScript, and CSS to perform focused tasks, many generated with LLMs.

It outlines core design patterns: keep each tool in a single small file, avoid React and build steps, load minimal dependencies from CDNs, and make code easy to copy, paste, and host. It also lists practical techniques like prototyping in LLM canvases, persisting state via URLs or localStorage, calling CORS-enabled APIs and LLMs directly, using Pyodide/WebAssembly, and reusing previous tools and prompts.