This is a tiny project that provides a super simple lookup table for bank routing numbers to bank names.

Note: Currently, we simply load the routing numbers and bank names into memory. There are approximately 20,656 banks in the database, so this will likely take up a few megabytes of memory in each process that loads the BankLookup::DB into memory.

In your Gemfile:

gem 'bank_lookup'

You need to instruct the gem to parse the database file. This gem ships with a file that will be periodically updated (you can also suppply your own). In an initializer, make sure you load the DB by parsing the data file:

# config/initializers/bank_lookup.rb
BankLookup::Parser.parse

Mount the API in your router:

MyApp::Application.routes.draw do
  mount BankLookup::API => 'lookup'
end

Now get some bank names:

curl https://example.com/lookup/bank_name?number=121202211
# => {"name":"CHARLES SCHWAB BANK","pretty_name":"Charles Schwab Bank"}