Simon Willison’s Weblog

zipdecode (Java Applet). Type a zip code (try 66044) and watch the USA get narrowed down. Brilliant.

Posted 17th September 2004 at 9:37 pm

Recent articles

OpenAI are quietly adopting skills, now available in ChatGPT and Codex CLI - 12th December 2025
GPT-5.2 - 11th December 2025
Useful patterns for building HTML tools - 10th December 2025

Monthly briefing

Sponsor me for $10/month and get a curated email digest of the month's most important LLM developments.

Pay me to send you less!

Sponsor & subscribe