diff --git a/Gemfile b/Gemfile
index f33c823..61e3858 100644
--- a/Gemfile
+++ b/Gemfile
@@ -1,7 +1,8 @@
 source 'http://rubygems.org'
 
 gem 'rack', '~> 1.6.0'
-gem 'grape', '~> 0.10.1'
+# gem 'grape', '~> 0.10.1'
+gem 'grape', path: '/Users/cdan/work/dan-corneanu/grape'
 gem 'grape-entity', '~> 0.4.4'
 gem 'json', '~> 1.7.7'
 gem 'newrelic_rpm', '~> 3.5.4.34'
@@ -10,6 +11,8 @@ gem 'rack-cors', '~> 0.2.8'
 gem 'grape-swagger', '~> 0.9.0'
 gem 'mime-types'
 gem 'nokogiri', '1.6.3.1'
+gem 'pry'
+gem 'pry-byebug'
 
 group :development do
   gem 'rake', '~> 10.0.3'
diff --git a/Gemfile.lock b/Gemfile.lock
index 91e5af4..d566caa 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -15,6 +15,8 @@ GEM
       ice_nine (~> 0.11.0)
       thread_safe (~> 0.3, >= 0.3.1)
     builder (3.2.2)
+    byebug (4.0.5)
+      columnize (= 0.9.0)
     capybara (2.4.4)
       mime-types (>= 1.16)
       nokogiri (>= 1.3.3)
@@ -28,10 +30,11 @@ GEM
     coderay (1.1.0)
     coercible (1.0.0)
       descendants_tracker (~> 0.0.1)
+    columnize (0.9.0)
     descendants_tracker (0.0.4)
       thread_safe (~> 0.3, >= 0.3.1)
     diff-lcs (1.2.5)
-    equalizer (0.0.9)
+    equalizer (0.0.11)
     ffi (1.9.6)
     formatador (0.2.5)
     grape (0.10.1)
@@ -68,7 +71,7 @@ GEM
       libnotify
       rb-inotify
       spoon
-    hashie (3.3.2)
+    hashie (3.4.1)
     hitimes (1.2.2)
     i18n (0.7.0)
     ice_nine (0.11.1)
@@ -102,6 +105,10 @@ GEM
       coderay (~> 1.1.0)
       method_source (~> 0.8.1)
       slop (~> 3.4)
+    pry-byebug (3.1.0)
+      byebug (~> 4.0)
+      pry (~> 0.10)
+    racc (1.4.12)
     rack (1.6.0)
     rack-accept (0.4.5)
       rack (>= 0.4)
@@ -149,7 +156,7 @@ GEM
       hitimes
     tzinfo (1.2.2)
       thread_safe (~> 0.1)
-    virtus (1.0.3)
+    virtus (1.0.5)
       axiom-types (~> 0.1)
       coercible (~> 1.0)
       descendants_tracker (~> 0.0, >= 0.0.3)
@@ -175,6 +182,8 @@ DEPENDENCIES
   newrelic-grape (~> 1.1.0)
   newrelic_rpm (~> 3.5.4.34)
   nokogiri (= 1.6.3.1)
+  pry
+  pry-byebug
   racc
   rack (~> 1.6.0)
   rack-cors (~> 0.2.8)
diff --git a/api/upload_big_file.rb b/api/upload_big_file.rb
new file mode 100644
index 0000000..f1da4eb
--- /dev/null
+++ b/api/upload_big_file.rb
@@ -0,0 +1,30 @@
+module Acme
+  class UploadBigFile < Grape::API
+    content_type :png, 'image/png'
+
+    desc 'Upload and download a big file of any format using IO.'
+    post 'big_download' do
+      filename = params[:file][:filename]
+      # content_type MIME::Types.type_for(filename)[0].to_s
+      content_type 'image/png'
+      env['api.format'] = :png
+      header 'Content-Disposition', "attachment; filename*=UTF-8''#{URI.escape(filename)}"
+
+      temp_file = params[:file][:tempfile]
+      body FileStreamer.new temp_file.path
+      nil
+    end
+  end
+
+  class FileStreamer
+    def initialize(file_path)
+      @file_path = file_path
+    end
+
+    def each(&blk)
+      File.open(@file_path, 'r') do |file|
+        file.each(10, &blk)
+      end
+    end
+  end
+end
diff --git a/app/api.rb b/app/api.rb
index 5a1a7bd..51f40cf 100644
--- a/app/api.rb
+++ b/app/api.rb
@@ -11,6 +11,7 @@ class API < Grape::API
     mount ::Acme::PostJson
     mount ::Acme::ContentType
     mount ::Acme::UploadFile
+    mount ::Acme::UploadBigFile
     mount ::Acme::Entities::API
     add_swagger_documentation api_version: 'v1'
   end
diff --git a/spec/api/upload_big_file_spec.rb b/spec/api/upload_big_file_spec.rb
new file mode 100644
index 0000000..0351807
--- /dev/null
+++ b/spec/api/upload_big_file_spec.rb
@@ -0,0 +1,20 @@
+require 'spec_helper'
+
+describe Acme::API do
+  include Rack::Test::Methods
+
+  def app
+    Acme::API
+  end
+
+  it 'uploads and downloads a PNG file' do
+    image_filename = 'spec/fixtures/grape_logo.png'
+    post '/api/big_download.png', file: Rack::Test::UploadedFile.new(image_filename, 'image/png', true)
+    expect(last_response.status).to eq(201)
+    expect(last_response.headers['Content-Type']).to eq('image/png')
+    expect(last_response.headers['Content-Disposition']).to eq("attachment; filename*=UTF-8''grape_logo.png")
+    File.open(image_filename, 'rb') do |io|
+      expect(last_response.body).to eq io.read
+    end
+  end
+end