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A Bitcoin-friendly, Anonymous Marketplace for Computing Power

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BitWrk - A Bitcoin-friendly, anonymous marketplace for computing power

In 2011, an open marketplace for computing power was a visionary concept. In 2014, it has become reality.

BitWrk is based on the idea that many of today's applications consume enormous amounts of computing power. Their thirst for CPU and GPU power is never satisfied. However expensive, your hardware is never enough.

Enter BitWrk, the first true Cloud 2.0 application:

  • The computing power you don't have can be provided by the internet, in a peer-to-peer fashion.
  • Small units of computation are dispatched to potentially thousands of participating peers, giving a huge performance boost.
  • Internet currencies such as Bitcoin are ideally suited to support the kind of micro-transactions necessary to make this work.

BitWrk = Crowd + Cloud

As a proof-of-concept use case, BitWrk comes with support for Blender, the Free 3D rendering software suite. Blender rendering is being accelerated by BitWrk today!

I want BitWrk to become a true community project. The best support you can give is to try it out and test it for errors! If you prefer to support BitWrk financially, consider sending some Bitcoins to tip4commit. They will be distributed to everybody who contributes code to BitWrk.

tip for next commit

Quick Start Instructions

For the impatient, this will get you running within 5 minutes.

These steps apply to users of Windows, Mac OS X and Linux, although there might be shortcuts for some users (like installing Go using the system's package manager).

For selling to work, you will need to open a TCP port of your choice. This usually means configuring your local DSL router. If you don't know what this means, please Google for "open incoming tcp port" :-)

Without an open port, you can still buy on the BitWrk network!

  • Step 1: Download and install Google's Go SDK to be able to compile BitWrk:

    From a command prompt, you should be able to run the "go" tools.

  • Step 2: Download and unpack the BitWrk client package from
  • Step 3: Compile and start the BitWrk client software: cd bitwrk-master

    # Now set GOPATH environment variable to directory root
    # Linux/Mac OS X users:
    export GOPATH=$(pwd)
    # Windows users:
    set GOPATH=%cd%
    # Now compile the BitWrk client software needed for buying and selling
    cd src/cmd/bitwrk-client
    go install
    # If everything went fine, the BitWrk client can be started now.
    # Port 8082 needs to be reachable for selling to work
    ../../../bin/bitwrk-client -extport 8082

    Now navigate your web browser to http://localhost:8081/ and keep it open during the following steps. You should see your account number (which has been randomly chosen) and your current balance of BTC 1.

    Your next step is to try buying and selling on the BitWrk network using Blender, BitWrk's first supported application.

Blender Integration

Starting with the 20140124 release, BitWrk supports the popular 3D rendering software, Blender (, as a proof-of-concept project.

Buying rendering power on BitWrk

If you are a Blender artist and you would like to try out the new Blender integration:

  • Perform steps 1 and 2 from the previous section.
  • Start Blender 2.69. Select a scene you like. Verify that it looks good when rendered with the "Cycles" rendering engine. Also make sure that "Path Tracing" is selected on the "Sampling" rendering properties panel ("Branched Path Tracing" is not supported yet).
  • Go to User Preferences -> Addons -> Install From File
  • Select You find it in BitWrk's bitwrk-blender folder.
  • An add-on called "Render: BitWrk Distributed Rendering" should show up. If not, search for the new plugin by entering "bitwrk" in the add-on search field.
  • Activate the add-on by pressing the checkbox next to the running man icon.
  • Back in the main window, you can now select "BitWrk distributed rendering" as the active rendering engine.
  • You should see a new panel, "BitWrk Settings Panel". Everything can be left as is for now.
  • Next time you hit render, the task is dispatched to the BitWrk service as several small tiles. You should browse to the BitWrk client's web UI (on http://localhost:8081/) to give the client permission to build interaction with the BitWrk service.

Selling rendering power on BitWrk

If you would like to sell Blender rendering on BitWrk, run the provided script "" the following way (you need to have Python > 3.2 installed, see

python3 --blender /Path/To/Blender/blender


BitWrk aims to be a marketplace for computing power. Rather than providing computing resources itself (like "cloud" service providers do), it is a marketplace where buyers and sellers meet.

In its core, BitWrk works like a stock exchange. The difference is that it's not stocks that are traded, but computing tasks. There are different kinds of computing tasks on BitWrk, just like there are different stocks traded on a stock exchange.

Buyers are people who wish to get some computing tasks done (as quickly as possible, and as cheap as possible). They profit from BitWrk because they get on-demand access to enormous computing resources, from their desktop computers.

Sellers are people who provide the service of handling those tasks to the public. They profit directly from the money earned in exchange.

Prices are determined by the rules of supply and demand. Participants may range from hobbyists to companies (both buyers, and sellers).

The use of Bitcoin as BitWrk's preferred currency guarantees a low entry barrier, especially for potential buyers, provided that the success of Bitcoin continues. It also enables registration-less, anonymous participation.

If, on the other hand, Bitcoin turns out not to be a good choice, that's not going to be a problem. BitWrk itself does not depend on it. Other currencies and payment methods can be integrated later on.


This project has been under heavy development for the last couple of months and currently consists of:

  • A rudimentary server written in Go (, running on Google App Engine. It exports an API for entering bids and updating transactions. The lifecycle of every transaction can be traced, and all communication is secured with Elliptic-Curve cryptographic signatures of the same kind than those that can be generated using the original Bitcoin client.
  • A client, also written in Go, that contains all necessary logic to perform both sides of a transaction. A browser-based user interface enables control of ongoing trades, registered workers and automatic trading mandates. The client is meant to act as a proxy, taking tasks from local programs and dispatching them to the BitWrk service. For sellers, it provides the service to offer local worker programs to the BitWrk exchange and to keep them busy.
  • "bitwrk-blender", an experimental integration into the Blender graphics software, consisting of, a Python addon which registers a new rendering engine, and, a script for sellers.
  • "gorays", a sample application. It's a simple raytracer demonstrating how to use BitWrk, and also, for developers, how to extend an existing application to leverage the BitWrk service.

In the current phase of development, there is no way to transfer money into or out of the BitWrk service. Thus, no actual money can be made or lost. Every new client account starts with 1 BTC virtual starting capital.


  • 2014-03-26: BitWrk is making big progress towards a new release. Many user interface enhancements, both in BitWrk's browser-based client, as well as in the Blender add-on, make working with BitWrk smoother every day. A huge boost in performace comes from a unique compression mechanism that reduces network transmissions to a minimum.
  • 2014-01-25: Experimental Blender integration is now available.
  • 2013-12-04: A lot of progress has been made on the client side. Basic management functionality is now available for trades, workers and mandates. The client identity is no longer randomly generated every time the client is started, but saved on disk. This is a necessary precondition for later being able to link Bitcoin transactions to the account
  • 2013-11-27: Some progress has been made, mainly on the client side. A sample application has been adapted to use BitWrk: See for the Rays raytracer project.
  • 2013-11-15: After a break of two months, development has continued. The client now has the ability to not only list activities, but also to ask the user for a permission (valid up to a specified number of trades or minutes) or to cancel not yet granted activities.
  • 2013-09-01: There is now a simple user interface that shows the account's current balance, annd lists currently scheduled activities. It is possible to cancel (forbid) activities interactively. There is now a REST API to register and unregister workers.
  • 2013-08-16: The client is now able to perform a full transaction. Both buyer and seller side are implemented. There is no mechanism to register workers yet, so a dummy worker is registered: The work package is sent to and the result is whatever that page returns.
  • 2013-08-08: The client no longer places a random bid on the server. Performing a POST to
    simulates how a buy appears to clients, where the result is just a copy of the work data. A rudimentary in-memory content-addressable file storage (CAFS) keeps files and serves them under
    http://localhost:8081/file/<sha256, hex-encoded>
    To see what's going on, execute:
    curl -v -F data=@<some filename> -L http://localhost:8081/buy/foobar


The client software provides a graphical web frontend that presents the user with a view of everything going on between the local machine and the BitWrk service.

Running the client is very straightforward: Just run

and navigate your Web browser to http://localhost:8081/.

There are also some command-line options:

$ ./bitwrk-client --help
Usage of bitwrk-client:
  -bitwrkurl="": URL to contact the bitwrk service at
  -extaddr="auto": IP address or name this host can be reached under from the internet
  -extport=-1: Port that can be reached from the Internet (-1 disables incoming connections)
  -intport=8081: Maintenance port for admin interface
  -log-cafs=false: Enable logging for content-addressable file storage
  -num-unmatched-bids=1: Mamimum number of unmatched bids for an article on server
  -resourcedir="auto": Directory where the bitwrk client loads resources from
The URL the client used to connect to the server. This is useful for testing locally or for using alternative BitWrk service providers.
-extaddr, -extport
If you would like to sell on Bitwrk, the buyers must be able to connect to your computer. You need to provide them with your host's DNS name or IP address, and a port number. If you are behind a firewall, you must setup your router to forward the port given here to your computer. See your router's documentation on "port forwarding" on how to accomplish this.
If your IP address is dynamic, it is best to leave -extaddr set to "auto". The client will find out which IP address to use. If -extport is set to "-1", selling on BitWrk is disabled.
The port number on which the client listens on for local connections. When left to the default value, the client's user interface will be reachable by opening http://localhost:8081/ in your web browser. Local programs will be able to dispatch work to the BitWrk network by doing a POST to http://localhost:8081/<article-id>, where <article-id identifies the article to trade. It must be an article that is traded on the BitWrk server.
Limits the number of not-yet-matched bids that are sent to the BitWrk service.

Identity Management

Every participant on the BitWrk service is identified by a unique and seemingly random combination of numbers and letters, called account id, something like 1JtLbmh74Tcb5CZk7eZZBH8z4zg4sjey1i

This ID serves two distinct purposes:

  • It is a unique user ID for participants of the BitWrk service.
  • It is also a valid address for receiving money in the Bitcoin (BTC) currency.

When communicating with the BitWrk service, such as when placing a bid, the client must authenticate, i.e. prove that it really is the the owner address it claims to have.

Then, after some time of selling work on BitWrk, the Money earned will be transferred (via Bitcoin) back to this address.

In order to be able to prove the ownership of its account ID, the BitWrk client must keep a secret file, called the private key.

On first start, a random private key (and a corresponding BitWrk account ID/Bitcoin address) is generated and stored on disk permanently (in a file only readable to the user running the BitWrk client: ~/.bitwrk-client/privatekey.wif). As the key is stored in a format called Wallet Interchange Format (WIF), it can be imported into a Bitcoin wallet using the importprivkey command. This gives the Bitcoin client access to the money sent to that Bitcoin address.

It is very important to have the private key file backed up in some safe place. It is also very important that neither the private key file, nor the backup be visible to others.


The server is a web application written for Google Appengine. Its purpose is to

  • accept bids from buyers and sellers
  • find matching bids and create transactions
  • listen for messages from clients updating the transactions
  • enforcing rules by which these transactions must be handled
  • do bookkeeping of the participants' accounts

As a user of BitWrk, you shouldn't need to worry about the server. You need to trust it, though, especially if you decide to send money to it (which as of now is not possible, but will be). As a trust-building measure, the server's source code is open-sourced, too.

Have fun! 2014-03-26, Jonas Eschenburg

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