img.bi is a secure image hosting. Images are encrypted using AES-256 with random key in browser before upload.
img.bi software is really old, not supported and you should not use it.
For alternative, check out icsend.
imgbi-server is a tool to build and host img.bi instance. I can be used alone, although it's recommended to use it with some webserver like nginx.
You can get imgbi-server from npm
npm install -g imgbi-server
See --help for usage info.