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A friendly Bitcoin vending machine, living inside a condom machine. See it live on
Ruby CSS Other


The Kondocoin is a friendly bitcoin vending machine for bitcoin newcomers. It allows you to sell vouchers for BTC: You generate a voucher for a given fiat currency value and sell it using any kind of vending machine. The customer then can enter the voucher's code on your website and get his BTC. The amount of BTC to be paid is calculated using the Bitstamp exchange rate (and the daily ECB Euro/Dollar conversion rate). This has the advantage that the payout value is fair for everyone: a pre-calculated bitcoin voucher might be worth a lot more (or less) when it is purchased. A disadvantage is that the customer has to trust the seller. For the very low amounts of BTC we're currently handling this should be acceptable. We're also accepting only fixed amounts of fiat currency, currently 2 Euro.

/Please: Consider running one in your hackerspace, promote the idea of a decentralized currency!/

This repository contains a Rails 4 application for handling the website part. The corresponding hardware is described in the wiki. Yes, this is an old condom vending machine. I've got it for approx. 60 Euro on ebay. As it turns out, you can also buy the little cardboard boxes that go into it on ebay. The setup has the advantage that it doesn't need any power, is robust and can also be mounted outdoors.

The system doesn't require any customer data except for his wallet id. This allows people to purchase a small amount of BTC anonymously. The basic operation of the software works like this:

  • Make sure to have a look at the config/application.yml for setting the Euro value of the voucher, the bitcoind access parameter etc.
  • You generate vouchers using rake voucher:generate.
  • You print them: rake voucher:print. The vouchers are now marked active within the database. Print the vouchers and put them into the vending machine.
  • A customer buys a voucher.
  • He enters the voucher code along with his wallet address. The server marks the voucher for payout in the database. The value of the voucher in BTC is calculated on the basis of the last Bitstamp quote.
  • Every five minutes a cronjob processes the payouts and triggers the transfer. This part is handled by an instance of bitcoind. Make sure the instance's balance is sufficient to pay for all active vouchers!

You can see a live (and operational) version of this software here:

Missing features

  • A warning email should be sent to the site operator when the funds are not sufficient for all vouchers.
  • Optional: a similar email for all payouts.


This software was carefully developed and tested. However, I cannot guarantee that there are no security vulnerabilities included - and maybe you introduce vulnerabilities by the way you're operating it. In the worst case, someone might steal your bitcoins. Or the world might come to an end. Or a lolcat dies. You have been warned.


 $ rvm use 2.0.0@kondocoin --create
 $ gem install rails
 $ bundle install # --without production (if you're just developing)
 $ bundle update
 $ bundle install

If the app complains about a missing database.yml, please generate a dummy rails environment and copy the default database.yml from it. The cronjobs can be installed using whenever -i

Most of the functionality is only available through rake. Please run

 $ rake -T

to see a list of available tasks.


Install bitcoind

See also: Install prerequisites.

# sudo apt-get install build-essential libboost-all-dev \
  libssl-dev libdb-dev libglib2.0-dev libdb5.1++-dev \

Create a user 'bitcoind'.

# adduser --system --disabled-login bitcoind

Clone and compile:

# cd /home/bitcoind
# git clone
# cd bitcoin/src
# make -f makefile.unix bitcoind
# mkdir ~/bin
# cp bitcoind ~/bin

Configure bitcoind:

$ vim /home/bitcoind/.bitcoin/bitcoin.conf
alertnotify=echo %s | mail -s "Bitcoin Alert" root@localhost

Create startup and log facitilies (using the daemontools)

$ apt-get install daemontools daemontools-run

$ mkdir /etc/service/bitcoind
$ cat <<__EOF__ > /etc/service/bitcoind/run
exec setuidgid bitcoind /home/bitcoind/bin/bitcoind 2>&1 
$ chmod 1755 /etc/service/bitcoind
$ chmod +x /etc/service/bitcoind/run

$ mkdir /etc/service/bitcoind/log
$ cat <<__EOF__ > /etc/service/bitcoind/log/run
exec multilog t /var/log/bitcoind
$ chmod +x /etc/service/bitcoind/log/run
$ mkdir -p /var/log/bitcoind

TODO: This needs more debugging. for now, the bitcoind runs in a tmux.

Installing the rails environment


An nginx config file is available in the config subdirectory. I use unicorn in my production environment - again, a suitable config file is available in the config subdirectory.

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