i2pd (I2P Daemon) is a full-featured C++ implementation of I2P client.

I2P (Invisible Internet Protocol) is a universal anonymous network
layer.  All communications over I2P are anonymous and end-to-end
encrypted, participants don't reveal their real IP addresses.

I2P client is a software used for building and using anonymous I2P
networks.  Such networks are commonly used for anonymous peer-to-peer
applications (filesharing, cryptocurrencies) and anonymous client-server
applications (websites, instant messengers, chat-servers).

I2P allows people from all around the world to communicate and share
information without restrictions.
