Google Reader "subscriptions.json" file to opml: ruby json_to_opml.rb /to/your/subscriptions.json > /to/your/saved/path

json_to_opml.rb

require 'multi_json'
require 'builder'

data = File.new(ARGF[0])
json = MultiJson.load(data)

feeds = {}
json["subscriptions"].each do | item |
  item["categories"].each do |cat|
    cat_name = cat["label"]
    feeds[cat_name] = [] if !feeds.has_key?(cat_name)
    feeds[cat_name].push({
      :type => 'rss',
      :title => item["title"],
      :text => item["title"],
      :htmlUrl => item["htmlUrl"],
      :xmlUrl => item["id"].gsub("feed/", "")
      })
  end
end

xml = Builder::XmlMarkup.new(:target => STDOUT, :indent => 4)
xml.instruct!
xml.opml(:version => 1.0) do
  xml.head do
    xml.title "icyleaf's feeds on Google Reader"
  end
  xml.body do
    feeds.each do | cat, items |
      xml.outline(:text => cat, :title => cat) do
        items.each do |item|
          xml.outline(item)
        end
      end 
    end
  end
end