The invisible internet protocol. It's some version of the Darknet (like tor), but you can only communicate with hidden services through it (There are no exit nodes). Because of that your IP isn't involved in transmitting the data.

I guess https://geti2p.net/en/

It is an anonymity network similar to tor if you have heard of that. I would recommend playing around with i2p+ to get started with it. You should be able to get it from here: https://i2pplus.github.io/

Last time I tried it, it was slow enough but it is did the job. Though it depends on the seeds, I suspect it is somewhat faster nowadays.