A few things everyone can do now:

  1. Please consider running a relay to help the Tor network grow.
  2. Tell your friends! Get them to run relays. Get them to run onion services. Get them to tell their friends.
  3. If you like Tor's goals, please take a moment to donate to support further Tor development. We're also looking for more sponsors — if you know any companies, NGOs, agencies, or other organizations that want anonymity / privacy / communications security, let them know about us.
  4. We're looking for more good examples of Tor users and Tor use cases. If you use Tor for a scenario or purpose not yet described on that page, and you're comfortable sharing it with us, we'd love to hear from you.


  1. Help translate the documentation into other languages. See the translation guidelines if you want to help out. We especially need Arabic or Farsi translations, for the many Tor users in censored areas.
  2. Evaluate and document our list of programs that can be configured to use Tor.
  3. We have a huge list of potentially useful programs that interface with Tor. Which ones are useful in which situations? Please help us test them out and document your results.


  1. Monitor some of our public mailing lists, like tor-talk, tor-relays, tor-dev, or tbb-dev, and summarize noteworthy changes into articles for our blog and newsletter.
  2. Create a presentation that can be used for various user group meetings around the world.
  3. Create a video about the positive uses of Tor, what Tor is, or how to use it. Some have already started on Tor's Media server, Howcast, and YouTube.
  4. Create a poster around a theme, such as "Tor for Freedom!"
  5. Create a t-shirt design that incorporates "Congratulations! You are using Tor!" in any language.
  6. Spread the word about Tor at a symposium or conference and use these Tor brochures in PDF and ODG format and translated to at least ten different languages as conversation starter.


Below are a list of Tor related projects we're developing and/or maintaining. Most discussions happen on IRC so if you're interested in any of these (or you have a project idea of your own), then please join us in #tor-dev. Don't be shy to ask questions, and don't hesitate to ask even if the main contributors aren't active at that moment.

For a presentation summarizing many of these projects see...

Name Category Language Activity Contributors
Tor Core C, Rust Heavy nickm, arma, dgoulet, asn, teor
Tor Browser Bundle Javascript, XUL, Scripting Heavy mikeperry, Pearl Crescent, GeKo
HTTPS Everywhere Browser Add-on Javascript Moderate pde, mikeperry
Nyx User Interface Python, Curses Moderate atagar
Orbot User Interface Java Moderate n8fr8
Tails OS image Sys Admin Heavy #tails
tor-ramdisk OS image Sys Admin Light blueness
Torsocks Usability C Light David Goulet
Tor Messenger Bundle JavaScript, XUL, Scripting None arlolra, boklm, sukhe
TorBirdy Browser Add-on JavaScript Light sukhe
Shadow Simulator C, Python Moderate robgjansen
Chutney Simulator Python Light teor
Stem Library Python Heavy atagar
Txtorcon Library Python, Twisted Moderate meejah
metrics-lib Library Java Moderate karsten, iwakeh
Metrics Client Service Java Heavy karsten, iwakeh
Relay Search Client Service JavaScript Light irl
Onionoo Backend Service Java Heavy karsten, iwakeh
ExitMap Backend Service Python None phw
DocTor Backend Service Python Light atagar
GetTor Client Service Python None ilv
TorCheck Client Service Go None Arlo
BridgeDB Backend Service Python Light isis
Ooni Probe Scanner Python Heavy hellais, aagbsn
TorPS Backend Service Python None Aaron Johnson
TorFlow Backend Service Python None aagbsn
CollecTor Backend Service Java Moderate karsten, iwakeh
ExoneraTor Client Service Java Light karsten, iwakeh
Anonbib Website Python None arma, nickm
* Project is still in an alpha state.

Tor (code, bug tracker)

Central project, providing the core software for using and participating in the Tor network. Numerous people contribute to the project to varying extents, but the chief architects are Nick Mathewson and Roger Dingledine.

Project Ideas:
Python Tor Client
Fuzzing coverage of Tor
Relay crypto parallelism
Anonymous local count statistics
Improved SOCKS5 variant
Onion service crypto parallelism
Support all kinds of DNS in Tor
Improve IPv6 support

Tor Browser (code, bug tracker, design doc)

Tor Browser is an easy-to-use, portable package of Tor, HTTPS-Everywhere, NoScript, TorLauncher, Torbutton, and a Firefox fork, all preconfigured to work together out of the box. The modified copy of Firefox aims to resolve the privacy and security issues in mainline version.

Project Ideas:
Remove metadata from Tor Browser uploads

HTTPS Everywhere (code, bug tracker)

HTTPS Everywhere is a Firefox and Chrome extension that encrypts your communications with many major websites, making your browsing more secure.

Nyx (code, bug tracker)

Nyx (previously arm) is a terminal status monitor for Tor intended for command-line aficionados, ssh connections, and anyone with a tty terminal. This works much like top does for system usage, providing real time statistics for bandwidth, resource usage, connections, and quite a bit more.

Orbot (code, bug tracker)

Provides Tor on the Android platform. The project is under active development, updates to latest Tor releases, and working to stay up to date with all changes in Android and mobile threats.

The Amnesic Incognito Live System (code, bug tracker, documentation, design, contribute)

The Amnesic Incognito Live System is a live CD/USB distribution preconfigured so that everything is safely routed through Tor and leaves no trace on the local system. This is a merger of the Amnesia and Incognito projects, and still under very active development.

Tor-ramdisk (code, documentation)

Tor-ramdisk is a uClibc-based micro Linux distribution whose sole purpose is to securely host a Tor server purely in RAM.

Torsocks (code, bug tracker)

Utility for adapting other applications to work with Tor. Development has slowed and compatibility issues remain with some platforms, but it's otherwise feature complete.

Tor Messenger (code, bug tracker)

Tor Messenger is a cross-platform chat program that aims to be secure by default and sends all of its traffic over Tor.

TorBirdy (code, bug tracker)

TorBirdy is Torbutton for Thunderbird and related Mozilla mail clients.

Shadow (code, bug tracker)

Shadow is a discrete-event network simulator that runs the real Tor software as a plug-in. Shadow is open-source software that enables accurate, efficient, controlled, and repeatable Tor experimentation. For another simulator, see ExperimenTor.

Chutney (code, bug tracker)

Integration test suite that spawns a local tor network, checking the interactions of its components.

Stem (code, bug tracker)

Python controller library for scripts and controller applications using Tor.

Project Ideas:
Python Tor Client

Txtorcon (code, bug tracker)

Twisted-based asynchronous Tor control protocol implementation. Includes unit-tests, examples, state-tracking code and configuration abstraction. Used by OONI and APAF.

metrics-lib (code, bug tracker)

metrics-lib is a Java library that processes Tor network data provided by CollecTor or from other sources.

Metrics (web)

Processing and analytics of consensus data, provided to users via the metrics portal. This has been under active development for several years by Karsten Loesing.

Relay Search (code)

Relay Search is a web application to discover Tor relays and bridges. It provides useful information on how relays are configured along with graphics about their past usage.

This is the spiritual successor to TorStatus, the original codebase for which was written in PHP, and rewritten by students from Wesleyan as Django. If you dig into this space then also check out Globe, another similar site that's since been discontinued.

Onionoo (code, bug tracker)

Onionoo is a JSON based protocol to learn information about currently running Tor relays and bridges.

ExitMap (code, bug tracker)

Scanner for the Tor network by Philipp Winter to detect malicious and misconfigured exits. For more information about how it works see his Spoiled Onions research paper.

DocTor (code, bug tracker)

DocTor is a notification service that monitors newly published descriptor information for issues. This is primarily a service to help the tor directory authority operators, but it also checks for a handful of other issues like sybil attacks.

Weather (code, bug tracker)

Provides automatic notification to subscribed relay operators when their relay's unreachable. This underwent a rewrite by the Wesleyan HFOSS team, which went live in early 2011.

GetTor (code, bug tracker)

E-mail autoresponder providing Tor's packages over SMTP. This has been relatively unchanged for quite a while.

TorCheck (code, bug tracker)

Site for determining if the visitor is using Tor or not.

BridgeDB (code, bug tracker)

Backend bridge distributor, handling the various pools they're distributed in. This was actively developed until Fall of 2010.

Ooni Probe (code, bug tracker)

Censorship scanner, checking your local connection for blocked or modified content.

TorPS (code)

The Tor Path Simulator (TorPS) is a tool for efficiently simulating path selection in Tor. It chooses circuits and assigns user streams to those circuits in the same way that Tor does. TorPS is fast enough to perform thousands of simulations over periods of months.

TorFlow (code, bug tracker)

Library and collection of services for actively monitoring the Tor network. These include the Bandwidth Scanners (measuring throughput of relays) and SoaT (scans for malicious or misconfigured exit nodes). SoaT was last actively developed in the Summer of 2010, and the Bandwidth Scanners a few months later. Both have been under active use since then, but development has stopped.

CollecTor (code, bug tracker)

CollecTor is the Tor network data archive that powers other services like Metrics and Onionoo.

ExoneraTor (code, bug tracker)

ExoneraTor is a service that answers the question whether there was a Tor relay running on a given IP address on a given date.

Anonymity Bibliography (code)

Anonbib is a list of important papers in the field of anonymity. It's also a set of scripts to generate the website from Latex (bibtex). If we're missing any important papers, please let us know!

Project Ideas

You may find some of these projects to be good ideas for Google Summer of Code or the Tor Summer of Privacy. We have labelled each idea with which of our core developers would be good mentors. If one or more of these ideas looks promising to you, please contact us to discuss your plans rather than sending blind applications. You may also want to propose your own project idea — which often results in the best applications.

  1. Remove metadata from Tor Browser uploads
    Likely Mentors: Arthur D. Edelstein (arthuredelstein)

    Tor Browser is a privacy-preserving web browser used by millions of users around the world. We are looking for a programmer fluent in JS and C++ to implement new features to work closely with the Tor Browser team.

    Image files, especially photos taken by smartphones, often carry hidden privacy-violating metadata, typically specified by the EXIF format. Such metadata can include the user's geolocation and various unique identifiers. In order to protect the user's identity, we would like the intern to modify the file-upload feature in Tor Browser such that metadata in image files is automatically removed before the image is uploaded to a server. Ideally, the summer intern would implement this feature for both desktop and mobile Tor Browser. If there is time, we can envision sanitizing other kinds of uploaded files, including movies, audio, PDFs and Office documents.

    For more information see its ticket. Please also see the Metadata Anonymisation Toolkit (MAT) for a similar project that could serve as inspiration.

  2. Python Tor Client
    Language: Python
    Likely Mentors: Damian (atagar), teor

    Stem is our Python implementation of Tor's varous protocols. Traditionally this included stem.control for Tor's ControlPort and stem.descriptor to download from Tor's DirPort. But recently we added a third to this family, stem.client, that speaks Tor's ORPort protocol: the relay protocol for usage of the Tor network itself.

    This opens interesting opportunities we've never had before such as...

    • Construct a full three-hop circuit that can make GET requests and DNS lookups. If done right this might allow simple usage of the Tor network without even having Tor installed!
    • Expand descriptor downloading to use Tor's ORPort as an optional alternative for the DirPort. Following this we could adjust Tor so Fallback Directories no longer require a DirPort.
    • Download hidden service descriptors. Unlike relays, the descriptors for hidden services are only available over the ORPort. Once ticket 17945 is merged v3 HS descriptor downloads will require a multi-hop circuit. This requires an understanding of Tor's hidden service specifications, particularly the HSDir hash ring.
    • Authenticate our ORPort connection, checking that ORPorts we connect to have the right key fingerprint.
    • Add protocol level integration test of Tor's ORPort, for instance exercising edge cases in circuit construction and extension.
    • Connect to a hidden service to check if it's up or not.

    And more! Applicants are encouraged to get a decent understanding of Tor's ORPort protocol and come up with ideas of their own for neat directions that we can take this. To be clear this is not a particularly easy beginner project as it involves expanding stem.client to support more of Tor's ORPort protocol and crypto.

    As part of applying for this project please get your hands wet with the codebase by contributing some patches for Stem!

  3. Fuzzing coverage of Tor
    Likely Mentors: Nick (nickm), ahf, teor

    Starting in 0.3.0.x, Tor supports a few fuzzing systems to check our code for bugs. But as of now, we only support a few possible entry points to Tor. It would be great to add fuzzing support for more of our codebase -- ideally to include our whole network-facing interface. That way, we could find more bugs in our code faster, and fix them before they can get out of hand.

    This won't be so easy, however: to fuzz effectively, we need to refactor or mock the target function so that it doesn't change any global state, or verify any signatures, or take too long to run. With lots of our network code, that's not so easy. Make sure you understand how our mocking system works, and what the challenges are, before you apply for this one.

  4. Relay crypto parallelism
    Likely Mentors: Isis, Nick (nickm)

    Tor relays spend a lot of time encrypting and decrypting relay traffic, doing SHA1 and AES-CTR operations. But right now, all of this is done in the main thread! It would be cool to split this across multiple cores instead.

    This won't be so easy though. The code today is written to expect immediate results from its encryption operations, so you would need to do some pretty tricky refactoring in order get performance and correctness here. Make sure you understand how circuit crypto is invoked today, and what the challenges are, before you apply for this one.

    For more information see its ticket.

  5. Anonymous local count statistics
    Likely Mentors: Nick (nickm), teor

    There are some places in Tor where we count things (like distinct IPs) to later report anonymized statistics. But if the local Tor instance were compromised, this data would be exposed. There are statistical methods which insteasd allow us to record this data in a way that's already anonymous, before we ever summarize it. Interested?

    For more information see its ticket.

  6. Improved SOCKS5 variant
    Likely Mentors: Nick (nickm), David Goulet (dgoulet), meejah

    In proposal 229, we describe a bunch of additional SOCKS extensions that Tor-aware applications could use to get more fine-grained control over how Tor handles their streams. It would be cool to implement this! If there's time remaining, you might want to add support to one or more applications. Or maybe to torsocks?

    For more information see its ticket.

  7. Onion service crypto parallelism
    Likely Mentors: Nick (nickm), David Goulet (dgoulet)

    Onion services, onion service clients, onion service directories, and introduction points all need to do a few public-key operations as they operate. But right now, these operations are all done on the main thread. It would be good to have these run across multiple cores.

    This could probably be done in a way similar to how we currently handle circuit extension handshakes in onion.c and cpuworker.c, but we'd need to extend the state machine for onion services to add an additional state. It could help onion services operate much more efficiently.

    For more information see its ticket.

  8. Support all kinds of DNS in Tor
    Likely Mentors: Nick (nickm), George (asn)

    Right now Tor can query for the kind of DNS information you'd find in A records, AAAA records, and PTR records. It would be neat to be able to support more general DNS queries to allow things like MX loopups, DNSSEC lookups, and so on. We have a design proposal (number 219) for this, but it might need some clean-up.

    For more information see its ticket.

  9. Improve IPv6 support
    Likely Mentors: ahf, teor

    Tor works over IPv6, but require some manual configuration. Clients and relays could automatically detect IPv6 availability, and configure themselves appropriately. Implementing a "happy eyeballs"-like algorithm is a challenge in an anonymity network: are you up for it?

    For more information see its ticket.

  10. Ahmia - Onion Service Search
    Language: Python, Django
    Likely Mentors: Juha Nurmi (numes), George (asn)

    Ahmia is open-source search engine software for Tor onion service deep dark web sites. You can test the running search engine at ahmia.fi. For more information see our blog post about Ahmia's GSoC2014 development.

    Ahmia is a working search engine that indexes, searches, and catalogs content published on Tor Onion Services. Furthermore, it is an environment to share meaningful insights, statistics, insights, and news about the Tor network itself. In this context, there is a lot of work to do.

    The Ahmia web service is written using the Django web framework. As a result, the server-side language is Python. On the client-side, most of the pages are plain HTML. There are some pages that require JavaScript, but the search itself works without client-side JavaScript.

  11. Bring up new ideas!
    Don't like any of these? Look at the Tor development roadmap for more ideas, or just try out Tor and Tor Browser, and find out what you think needs fixing. Some of the current proposals might also be short on developers.

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