Onion Browser | Tor Blog

Strength in Numbers: An Entire Ecosystem Relies on Tor

If the Tor Project, the Tor network, and Tor Browser were to disappear, what would happen? Not only would millions of global, daily users lose access to Tor’s software, but the diverse ecosystem of privacy, security, and anti-censorship applications that rely on the Tor network would cease to function.

Tor at the Heart: Onion Browser (and more iOS Tor)

During the month of December, we're highlighting other organizations and projects that rely on Tor, build on Tor, or are accomplishing their missions better because Tor exists.

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Recent Updates

New release: Tor 0.4.1.5

After months of work, we have a new stable release series! If you build Tor from source, you can download the source code for 0.4.1.5 on the website. Packages should be available within the next several weeks, with a new Tor Browser in early September.

This is the first stable release in the 0.4.1.x series. This series adds experimental circuit-level padding, authenticated SENDME cells to defend against certain attacks, and several performance improvements to save on CPU consumption. It fixes bugs in bootstrapping and v3 onion services. It also includes numerous smaller features and bugfixes on earlier versions.

Per our support policy, we will support the 0.4.1.x series for nine months, or until three months after the release of a stable 0.4.2.x: whichever is longer. If you need longer-term support, please stick with 0.3.5.x, which will we plan to support until Feb 2022.

Below are the changes since 0.4.0.5. For a list of only the changes since 0.4.1.4-rc, see the ChangeLog file.

Changes in version 0.4.1.5 - 2019-08-20

Directory authority changes:
- The directory authority "dizum" has a new IP address. Closes ticket 31406.
Major features (circuit padding):
- Onion service clients now add padding cells at the start of their INTRODUCE and RENDEZVOUS circuits, to make those circuits' traffic look more like general purpose Exit traffic. The overhead for this is 2 extra cells in each direction for RENDEZVOUS circuits, and 1 extra upstream cell and 10 downstream cells for INTRODUCE circuits. This feature is only enabled when also supported by the circuit's middle node. (Clients may specify fixed middle nodes with the MiddleNodes option, and may force-disable this feature with the CircuitPadding option.) Closes ticket 28634.

New Release: Tor Browser 9.0a5

Tor Browser 9.0a5 is now available for Android from our distribution directory and

Tor’s Bug Smash Fund: Help Tor smash all the bugs!

Say hello to our Bug Smash Fund.

New release candidate: Tor 0.4.1.4-rc

There's a new release candidate available for download. If you build Tor from source, you can download the source code for 0.4.1.4-rc from the usual place on the website. Packages should be available over the coming weeks, with a new alpha Tor Browser release likely in the next month or so.

Remember, this is just a release candidate: you should only run this if you'd like to find and report bugs.

Tor 0.4.1.4-rc fixes a few bugs from previous versions of Tor, and updates to a new list of fallback directories. If no new bugs are found, the next release in the 0.4.1.x series should be stable.

Changes in version 0.4.1.4-rc - 2019-07-25

Major bugfixes (circuit build, guard):
- When considering upgrading circuits from "waiting for guard" to "open", always ignore circuits that are marked for close. Otherwise, we can end up in the situation where a subsystem is notified that a closing circuit has just opened, leading to undesirable behavior. Fixes bug 30871; bugfix on 0.3.0.1-alpha.
Minor features (continuous integration):
- Our Travis configuration now uses Chutney to run some network integration tests automatically. Closes ticket 29280.