Simon Willison’s Weblog

25th January 2009 - Link Blog

OCR and Neural Nets in JavaScript. John dissects the brilliant Greasemonkey script that solves simple captchas using the canvas element and HTML5’s getImageData API.

Posted 25th January 2009 at 12 am

Recent articles

A new feature for my blog, built using my voice - 9th October 2026
Claude Haiku 5.5 - 7th October 2026
We're going to need default hard budget caps on pretty much everything - 3rd October 2026
OpenAI DevDay 2026 live blog - 29th September 2026

This is a link post by Simon Willison, posted on 25th January 2009.

canvas 38 captchas 9 getimagedata 1 greasemonkey 54 javascript 766 john-resig 33 ocr 26

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