Tor vs I2P: one gets you onto the web, the other never leaves
Tor vs I2P is a choice of errands, not a ranking. Tor is how you open an ordinary website, or an onion site, without the site learning your address. I2P is a network that mostly stays inside itself: the sites live on it, and so do you. If you came here to be told which one is more anonymous, there isn't a winner. They fail different jobs.
I2P's own comparison can't agree with itself
I2P's comparison page tells you to use I2P for anonymous browsing of the ordinary web. Another row on the same page marks an exit onto that web as limited, and discouraged. A network that discourages the way out is an odd thing to recommend for browsing.
The older, plainer account is the one to trust. I2P's own technical introduction says the two projects split the work: Tor aims at fast anonymous access out to the internet, and I2P aims at a resilient network that is the destination. The intro still says I2P itself is not an outproxy network. A few volunteers run proxies that step out onto the web. That is an application someone chose to run, not the design. When you use one, you are trusting that volunteer the way a Tor user trusts an exit relay, except there are far fewer of them, so you are easier to notice.
Read the comparison page as an advertisement that got ahead of the software. The design is the part that has been true for years.
Someone has to talk to the website
Tor's last relay is a person who has agreed to be the one that touches the real internet. The site sees their address, not yours. If the page isn't encrypted, that relay can read it. Abuse mail for whatever you did arrives at them. That is the price of a network whose job is to leave. Tor's description of the result is the short one: your provider shouldn't see which site you opened, and the site sees an exit instead of you. How the three relays split that is the page about Tor itself.
- Exit relay
- The last Tor hop. It talks to the website. You need one whenever the site is on the ordinary internet.
- Outproxy
- A volunteer doing that same job for I2P. The network does not provide one. There are few, and using one is not the same as browsing with Tor.
I2P doesn't appoint that person. There is no official exit. Both sides of a conversation are on the network, which is why a site that exists only as a .i2p name can hide the server as well as the visitor. An onion site does a version of this too, but the ordinary web cannot: the news site is not going to join your anonymity network. For that site, Tor's exit is the only one of the two that can reach it without borrowing a stranger's proxy.
The path is the other difference you can picture. On Tor the question and the answer share a circuit, so a bad relay at your end is in a position to see both directions, still encrypted, but as one conversation. On I2P the question leaves by one tunnel and the answer comes back by another. One router on the way is only supposed to see half. I2P can also pack several messages into one encrypted bundle. The word for that is garlic. It means a watcher counting packets cannot tell how many conversations are in the bag. Neither trick makes the smaller network the safer place to hide. It changes what a single bad router learns.
Who else is on it
The size of the network matters, because you hide among the other people using it. Tor is the large one. How many people that is, by country, is Tor's own measurements. I2P's comparison page puts itself at about 55,000 routers and Tor at millions of daily users. Take the second number from Tor, not from I2P. Take the first as their advertisement. Even if the router count is roughly right, a router is not a person browsing, and the crowd is still much smaller. In a small country, simply being on I2P can be the unusual fact.
Joining also feels different, because of who carries the traffic. On Tor most people are only clients. A smaller set run relays. On I2P, every router routes for other people. The moment you connect, you are part of the machinery, spending bandwidth on strangers. That is a fair trade if you wanted the network. It is a surprise if you only wanted to open a newspaper.
Tor's failures are the ones that have been walked through in public, including the cases where a person was identified anyway. Those cases are collected on the tracing page. I2P has not had the same number of people trying to break it, or writing up what worked. A quieter record is not a cleaner one.
Which one, for the thing you actually want
| You want | Use |
|---|---|
| A normal website, without the site learning your address | Tor. This is the job it is built for. |
| An onion site, or a guide that assumes Tor Browser | Tor. The browser, and how to check you downloaded the real one, is its own page. |
| A site or a file transfer that never has to pass through an exit | I2P. Both ends stay on the network. That is the case its design wins. |
| Whichever is more anonymous | Is I2P more anonymous than Tor? Only if the other person is on I2P too, and you are still hiding in the smaller crowd. For the web, Tor. |
| Tor is blocked where you are | A bridge, not a smaller network. Which bridge, by country, is the page for that. |
Running both does not average them into a stronger tool. Your provider can see you join each one. A VPN is a third, different object: one company that can see both ends. That comparison is separate. I2P is not the private upgrade to Tor. It is the other room. Where it sits next to Tor and Hyphanet, as a kind of dark web, is the short version. This page is the choice.