Objectively, what are the advantages and disadvantages of Tor with respect to JonDonym (formerly known as JAP) in the sense of security and anonymity?
JonDo now accepts Bitcoins for premium accounts...
Anonymous payments for JonDonym premium accounts are possible by Paysafecard (Euro, Dollar) and by snake mail letter too. See "Available billing methods" at
For better anonymity, one can sign up using JonDonym free services, but Tor works too.
Some other points for comparison of both services:
Funding: TorProject.org is mainly funded by US government over the last years (see financial reports of TorProject.org). JonDonym is funded only by users (premium users) and don't get money from governments any more. (Startup of JonDonym was funded by German government from 2000-2004).
Research: Both projects are supported by scientific research of universities. May be, Tor gets a bit more attention, I don't have a full list for counting publication.
Authority Servers / Infoservices: An anonymisation service doesn't contain only relays. Authority servers (Tor) and Infoservices (JonDo/JAP) are another component. (Only different names used by Tor and JonDo for same function - both provide information about running relays.)
3 of 5 Authority servers (Tor) are operated by members/developers of TorProject. 1 of 5 infoservices is operated by JonDos GmbH. I think, this fact may influence the point of centralization of main components in the discussion.
Sorry for my onesided view. It is only my input for the discussion. TorProject my feature out the advantages for Tor by self. ;-)
Mix networks get their security from the mixing done by their component mixes, and may or may not use route unpredictability to enhance security. Onion routing networks primarily get their security from choosing routes that are difficult for the adversary to observe, which for designs deployed to date has meant choosing unpredictable routes through a network. And onion routers typically employ no mixing at all. This gets at the essence of the two even if it is a bit too quick on both sides. Mixes are also usually intended to resist an adversary that can observe all traffic everywhere and, in some threat models, to actively change traffic. Onion routing assumes that an adversary who observes both ends of a communication path will completely break the anonymity of its traffic. Thus, onion routing networks are designed to resist a local adversary, one that can only see a subset of the network and the traffic on it.
See this JonDonym page for further discussion of differences.
Also, Tor is an open network of untrusted relays. Anyone can run a relay, and Tor is expressly designed to resist compromise by malicious relays. JonDonym is a closed network of trusted mixes. According to this JonDonym FAQ:
JonDonym is a development branch of the AN.ON project. And JAP is the predecessor of JonDo, the client software which connects users to the JonDonym/AN.ON mix network. JonDos is the company which is actively developing JonDo and is the billing instance between the users and the mix operators.
Mix operators must be certified, as outlined here:
JonDonym works in a different way than Tor or I2P. You cannot start a mix server and hope, you will be part of the anonymous proxy service. You have to become a verified mix operator first.
There are other differences as well. Tor provides notoriously low and variable bandwidth. That reflects its open design, and its price (free). JonDonym provides both free and premium versions. The free version is slower than most Tor circuits, while the premium version is faster than most Tor circuits.
JonDonym now accepts Bitcoins for premium accounts. For better anonymity, one can sign up using Tor, and pay with Bitcoins that have been throughly anonymized via Tor. Searching Tor.SE will lead you to more from me about that.
Given that JonDonym is more centralized than Tor, it's arguably more vulnerable to coercion by LEA and various TLAs. The FAQ referenced above addresses many of these issues.
JonDonym is still tarred by its cooperation in 2003 under a warrant from the German BKA. I gather that some of its relays logged IP addresses that accessed child pornography. The warrant was later judged unlawful. Also, JonDonym (then called JAP) made efforts to alert its users to the investigation.