Simon Willison’s Weblog

JavaScript/CSS Font Detector (via) Really clever trick: detects the fonts that you have installed by writing out some text and measuring its dimensions.

Posted 20th March 2007 at 11:20 pm

Recent articles

Video + notes on upgrading a Datasette plugin for the latest 1.0 alpha, with help from uv and OpenAI Codex CLI - 6th November 2025
Code research projects with async coding agents like Claude Code and Codex - 6th November 2025
A new SQL-powered permissions system in Datasette 1.0a20 - 4th November 2025

css 229 fonts 12 javascript 724

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