@simonw - Here's a collection of useful patterns I've found after

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Simon Willison✓@simonw

Here's a collection of useful patterns I've found after vibe-coding 150 different single-file HTML tools over the past couple of years https://simonwillison.net/2025/Dec/10/html-tools/

The anatomy of an HTML tool
Prototype with Artifacts or Canvas
Switch to a coding agent for more complex projects
Load dependencies from CDNs
Host them somewhere else
Take advantage of copy and paste
Build debugging tools
Persist state in the URL
Use localStorage for secrets or larger state
Collect CORS-enabled APIs
LLMs can be called directly via CORS
Don’t be afraid of opening files
You can offer downloadable files too
Pyodide can run Python code in the browser
WebAssembly opens more possibilities
Remix your previous tools
Record the prompt and transcript
Go forth and build

Screenshot of PyPI package changelog tool showing the differences between llm 0.27 and 0.27.1 with a copy diff button

Screenshot of SVG to JPEG/PNG tool showing the classic SVG tiger with options to convert to JPG or PNG with a custom background color and output width