There are a great many other applications and projects working on anonymous communication and I2P has been inspired by much of their efforts. This is not a comprehensive list of anonymity resources - both freehaven's Anonymity Bibliography and GNUnet's related projects serve that purpose well. That said, a few systems stand out for further comparison. The following have individual comparison pages:
Darknet. The word in and of itself brings to mind visions of the seedy underbelly of the internet; a virtual red-light district, back alley, and digital ghetto all rolled into one. Despite this threatening image that the media and many governments would like to imprint on the public consciousness, privacy-aware individuals know that in todays world of ISP data retention being measured in petabytes and massive supercomputing resources being thrown at traffic analysis by both governments and private industry alike, individuals must take it upon themselves to ensure the freedoms that come with anonymous information access and communication. Two of the most popular tools for doing so on the internet are Tor and I2P. Both will be compared and contrasted below.