This API provides access to the Amazon Flexible Payment Service (FPS). After trying to get the SOAP version of the API written, I began working on this REST version to provide a cohesive means of access to all of the functionality of the FPS without having to get dirty dealing with SOAP requests.

I hope you enjoy using it as much as I've enjoyed writing it. I'm interested to hear what sort of uses you find for it. If you find any bugs, let me know (or better yet, submit a patch).


Amazon provides a testing environment for the FPS called a sandbox. You may (and should) use the sandbox while testing your application. It can be enabled by passing a value of true to the last argument of the API constructor.

Getting Started

The following example shows how to load up the API, initialize the service, and make a simple call to get the tokens stored on the account:

gem 'remit'
require 'remit'

ACCESS_KEY = '<your AWS access key>'
SECRET_KEY = '<your AWS secret key>'

# connect using the API's sandbox mode
remit =, SECRET_KEY, true)

response = remit.get_tokens
puts response.tokens.first.token_id

VerifySignature API

See spec/integrations/verify_signature_spec.rb for examples on correct and incorrect usage!

Using with Rails

To use Remit in a Rails application, you must first specify a dependency on the Remit gem in your Gemfile:

gem 'remit'

Then you should create an initializer to configure your Amazon keys. Create the file config/initializers/remit.rb with the following contents:

config_file = File.join(Rails.root, 'config', 'amazon_fps.yml')
config = YAML.load_file(config_file)[RAILS_ENV].symbolize_keys

FPS_ACCESS_KEY = config[:access_key]
FPS_SECRET_KEY = config[:secret_key]

Then create the YAML file config/amazon_fps.yml:

development: &sandbox
  access_key: <your sandbox access key>
  secret_key: <your sandbox secret key>

  <<: *sandbox

  access_key: <your access key>
  secret_key: <your secret key>

To instantiate and use the Remit API in your application, you could define a method in your ApplicationController like this:

def remit
  @remit ||= begin
    sandbox = !Rails.env.production?, FPS_SECRET_KEY, sandbox)

Sites Using Remit

The following production sites are currently using Remit:

Amazon API Compliance

These are the changes summarized by Amazon from the previous API, and the level of compliance in this branch:

  1. You don't have to use InstallPaymentInstruction API to create Caller and Recipient tokens for your account. A Recipient token is now required only in Marketplace applications. We have completely removed the Caller token. Compliance: Caller token references removed.
  2. We removed parameters that are not being used by you today. For example, we removed metadata and recipient description, but we retained sender description and caller description. Compliance: DONE! recipient_description and metadata have been removed from the code.
  3. We simplified the transaction response object. Compliance: The former Remit::TransactionResponse object has been accordingly simplified.
  4. We simplified the GetTransaction response by removing unnecessary parameters. Compliance: ?
  5. By default, implicit retry and cancel will be the method used to handle temporary declines rather than the current explicit retry process. Compliance: Removed deprecated statuses
  6. GetResults, DiscardResults are replaced with GetTransactionStatus API. Compliance: GetResults and Discard Results are gone. GetTransactionStatus takes their place.
  7. Temporary decline status is not exposed to customers as we provide a simpler way to handle this status. Compliance: Temporary decline status can no longer be tested for, as it will never be a status.
  8. Web Service notification is removed and replaced with simplified IPN (Instant Payment Notification) mechanism.

Running Specification Suite

  1. Copy to
  2. Edit to have valid Amazon developer account access and secret keys
  3. Run ./ from the command line.

Copyright (c) 2007-2009 Tyler Hunt, released under the MIT license