Head to /new for a captcha.
The response will be in JSON format, with:
- md5 field having the md5 of the answer
- link field having a relative link to the image
- token field being a token you can use to identify this captcha in your cache
The captcha will expire and the image will be removed within 5 minutes.

The code is here: https://github.com/koto-bank/kocaptcha

Captchas generated since last restart: 7063