A currency conversion api for the minimalist developer
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Arbolito is a minimalist Ruby API for currency conversions, it has no dependencies except the Ruby Standard Library.

It's like your Florida street best companion!

Florida Street


  • Doesn't encapsulates the currencies in any object model, it just use BigDecimal class and Hash
  • You can add manually price rates
  • If the rate isn't found it fetches the rate using Yahoo Finance API as exchange or you can implement your own exchange.
  • You implement your own exchange and configure it
  • It stores in memory the rates fetched with a configurable expiration time
  • You can implement your own store and configure it
  • All the examples use the ISO 4217 code list for Currencies


There were two reason why I've developed this gem.

First the argetine economy makes difficult to keep the prices updated with official exchanges rates like Yahoo Finance, so we had to manage our own prices rates. But also I wanted to know the rates of other currencies through Yahoo Finance. This gem lets you do both.

The second reason is that other gems implements their own money or currency model, and I didn't want to update all my models to manage those objects. That's why I tried to be agnostic on how you implement your currencies.

The API just receives a Big Decimal and a hash describing the conversion


Add this line to your application's Gemfile:

gem 'arbolito'

And then execute:

$ bundle

Or install it yourself as:

$ gem install arbolito


require 'arbolito'

# We can add multiple rates

Arbolito.add_currency_rate(BigDecimal.new(9), 'USD' => 'ARS')
Arbolito.add_currency_rate(BigDecimal.new(15), 'USD Blue' => 'ARS')
Arbolito.add_currency_rate(BigDecimal.new(12), 'USD Tarjeta' => 'ARS')
Arbolito.add_currency_rate(BigDecimal.new(6.5), 'USD Moreno' => 'ARS')

# It gives the stored rate
Arbolito.current_rate('USD' => 'ARS')
# => #<BigDecimal:7f061f0787e0,'0.15E2',9(27)>

# It stored rate backwards
Arbolito.current_rate('ARS' => 'USD')
# => #<BigDecimal:7f061f076af8,'0.6666666666 6666667E-1',18(36)>

# It can make the conversion for you
Arbolito.convert(BigDecimal.new(100), 'USD' => 'ARS')
# => #<BigDecimal:7f061f1bd010,'0.15E4',9(27)>

Arbolito.convert(BigDecimal.new(100), 'USD Tarjeta' => 'ARS')
=> #<BigDecimal:7f061f39c818,'0.12E4',9(27)>

# Now we ask for the Uruguayan pesos to USD rate
Arbolito.current_rate('UYU' => 'USD')

# Now we ask to convert USD to Chilean Pesos
Arbolito.convert(BigDecimal.new(100), 'USD' => 'CLP')
=> #<BigDecimal:7f061f35e680,'0.689695E5',18(36)>

# We can configure Arbolito expiration in seconds
Arbolito.set(:expiration_time, 5 * 60)

# We can implement our own Exchange and configure it in Arbolito 
Arbolito.set(:exchange, Exchange::FloridaStreet)

# We can implement our own Store and configure it in Arbolito 
Arbolito.set(:store, Store::Mongo)

Update: 2017-11-03

Yahoo discountinued their Yahoo Finance API so I've implemented another Exchange Alpha Vantage.

To use you need to get an API Key from them and the configure it like this.

api_key = ENV['API_KEY']
Arbolito.set(:exchange, Arbolito::Exchange::AlphaVantage.new(api_key))

Implementing Store and Exchange

Please take a look at the code to see how you can implement your own stores and exchanges.


Bug reports and pull requests are welcome on GitHub at https://github.com/jvillarjeo/arbolito. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.


The gem is available as open source under the terms of the MIT License.