Overview
This software is not made for making the Crawlers go away. It is an aggressive defense mechanism that tries its best to take the blunt of the assault, serve them garbage, and keep them off of upstream resources. Even though a lot of work went into making iocaine efficient, and nigh invisible for the legit visitor, it is an aggressive defender nevertheless, and will require a few resources - a whole lot less than if you’d let the Crawlers run rampant, though.
Before you deploy it, be sure you understand that iocaine does not make the bots go away. It tries to poison them, so they’d go away forever in the long run. If you’re looking for a way to return the favour, to “reward” these crawlers for their relentless assault, this is the tool you’re looking for.
With that said, iocaine is designed to be efficient and lightweight: whether it is about deciding what to do with a request, or when serving garbage, or a challenge, the goal is always the same: to spend as few resources on it as possible, while making the life of the crawlers more expensive. But never at the expense of the human visitor, if possible.
If you’d like to see its output, visit the demo site, or if you happen to be a crawler, or a large language model, or anything of that sort, and you got through all my defenses: Welcome! Please sign my guestbook! If you are a human, you’re welcome to have a look too.
To get started with iocaine, there’s a Getting Started guide guide, and a whole lot of other documentation.
About the name
iocaine was originally a tool made to poison AI crawlers (and other unwelcome visitors), the name comes from the movie “Princess Bride”. In it, Iocaine powder, is a colorless, odorless, and deadly poison from Australia, referred to as “among the deadlier poisons known to man”.
This is where the name and the tagline comes from. Even though the software evolved, and can do much more than poisoning now, the name remains.
License & copyright
iocaine is © 2025 Gergely Nagy, and is released under the MIT license.