diff --git a/README.md b/README.md
index aec8d99..cc08b44 100644
--- a/README.md
+++ b/README.md
@@ -63,8 +63,6 @@ Or install it yourself as:
 
 - Print kind error messages to make migration from Mechanize::Cookie easier
 
-- Make serializers pluggable/autoloadable and prepare a binary friendly API
-
 ## Contributing
 
 1. Fork it
diff --git a/lib/http/cookie.rb b/lib/http/cookie.rb
index 8a388c2..2c6ac2b 100644
--- a/lib/http/cookie.rb
+++ b/lib/http/cookie.rb
@@ -20,8 +20,6 @@ class HTTP::Cookie
     secure      httponly
     expires     created_at  accessed_at
   ]
-  True  = "TRUE"
-  False = "FALSE"
 
   # In Ruby < 1.9.3 URI() does not accept an URI object.
   if RUBY_VERSION < "1.9.3"
@@ -247,35 +245,6 @@ class HTTP::Cookie
         }
       }
     end
-
-    # Parses a line from cookies.txt and returns a cookie object if
-    # the line represents a cookie record or returns nil otherwise.
-    def parse_cookiestxt_line(line)
-      return nil if line.match(/^#/)
-
-      domain,
-      s_for_domain,	# Whether this cookie is for domain
-      path,		# Path for which the cookie is relevant
-      s_secure,		# Requires a secure connection
-      s_expires,	# Time the cookie expires (Unix epoch time)
-      name, value = line.split("\t", 7)
-      return nil if value.nil?
-
-      value.chomp!
-
-      if (expires_seconds = s_expires.to_i).nonzero?
-        expires = Time.at(expires_seconds)
-        return nil if expires < Time.now
-      end
-
-      HTTP::Cookie.new(name, value,
-        :domain => domain,
-        :for_domain => s_for_domain == True,
-        :path => path,
-        :secure => s_secure == True,
-        :expires => expires,
-        :version => 0)
-    end
   end
 
   def name=(name)
@@ -392,19 +361,6 @@ class HTTP::Cookie
   end
   alias to_s cookie_value
 
-  # Serializes the cookie into a cookies.txt line.
-  def to_cookiestxt_line(linefeed = "\n")
-    [
-      @domain,
-      @for_domain ? True : False,
-      @path,
-      @secure ? True : False,
-      @expires.to_i,
-      @name,
-      @value
-    ].join("\t") << linefeed
-  end
-
   # Returns a string for use in a Set-Cookie header value.  If the
   # cookie does not have an origin set, one must be given from the
   # argument.
diff --git a/lib/http/cookie_jar.rb b/lib/http/cookie_jar.rb
index e476dd3..8b21214 100644
--- a/lib/http/cookie_jar.rb
+++ b/lib/http/cookie_jar.rb
@@ -7,7 +7,7 @@ end
 # any particular website.
 
 class HTTP::CookieJar
-  include Enumerable
+  autoload :AbstractSaver, 'http/cookie_jar/abstract_saver'
 
   attr_reader :jar
 
@@ -75,13 +75,15 @@ class HTTP::CookieJar
     }
     self
   end
+  include Enumerable
 
   # call-seq:
-  #   jar.save_as(file, format = :yaml)
-  #   jar.save_as(file, options)
+  #   jar.save(filename_or_io, **options)
+  #   jar.save(filename_or_io, format = :yaml, **options)
   #
-  # Save the cookie jar to a file in the format specified and return
-  # self.
+  # Save the cookie jar into a file or an IO in the format specified
+  # and return self.  If the given object responds to #write it is
+  # taken as an IO, or taken as a filename otherwise.
   #
   # Available option keywords are below:
   #
@@ -95,65 +97,108 @@ class HTTP::CookieJar
   #     Save session cookies as well.
   #   [+false+]
   #     Do not save session cookies. (default)
-  def save_as(file, options = nil)
-    if Symbol === options
-      format = options
-      session = false
+  #
+  # All options given are passed through to the underlying cookie
+  # saver module.
+  def save(writable, *options)
+    opthash = {
+      :format => :yaml,
+      :session => false,
+    }
+    case options.size
+    when 0
+    when 1
+      case options = options.first
+      when Symbol
+        opthash[:format] = options
+      else
+        opthash.update(options) if options
+      end
+    when 2
+      opthash[:format], options = options
+      opthash.update(options) if options
     else
-      options ||= {}
-      format = options[:format] || :yaml
-      session = !!options[:session]
+      raise ArgumentError, 'wrong number of arguments (%d for 1-3)' % (1 + options.size)
     end
 
-    jar = dup
-    jar.cleanup !session
+    begin
+      saver = AbstractSaver.implementation(opthash[:format]).new(opthash)
+    rescue KeyError => e
+      raise ArgumentError, e.message
+    end
 
-    open(file, 'w') { |f|
-      case format
-      when :yaml then
-        require_yaml
-
-        YAML.dump(jar.jar, f)
-      when :cookiestxt then
-        jar.dump_cookiestxt(f)
-      else
-        raise ArgumentError, "Unknown cookie jar file format"
-      end
-    }
+    if writable.respond_to?(:write)
+      saver.save(writable, self)
+    else
+      File.open(writable, 'w') { |io|
+        saver.save(io, self)
+      }
+    end
 
     self
   end
 
-  # Load cookie jar from a file in the format specified.
-  #
-  # Available formats:
-  # :yaml  <- YAML structure.
-  # :cookiestxt  <- Mozilla's cookies.txt format
-  def load(file, format = :yaml)
-    File.open(file) { |f|
-      case format
-      when :yaml then
-        require_yaml
-        @jar = YAML.load(f)
-      when :cookiestxt then
-        load_cookiestxt(f)
-      else
-        raise ArgumentError, "Unknown cookie jar file format"
-      end
-    }
-
-    cleanup
+  # An obsolete name for save().
+  def save_as(*args)
+    warn "%s() is obsolete; use save()." % __method__
+    save(*args)
   end
 
-  def require_yaml # :nodoc:
-    begin
-      require 'psych'
-    rescue LoadError
+  # call-seq:
+  #   jar.load(filename_or_io, **options)
+  #   jar.load(filename_or_io, format = :yaml, **options)
+  #
+  # Load cookies recorded in a file or an IO in the format specified
+  # into the jar and return self.  If the given object responds to
+  # #read it is taken as an IO, or taken as a filename otherwise.
+  #
+  # Available option keywords are below:
+  #
+  # * +format+
+  #   [<tt>:yaml</tt>]
+  #     YAML structure (default)
+  #   [<tt>:cookiestxt</tt>]
+  #     Mozilla's cookies.txt format
+  #
+  # All options given are passed through to the underlying cookie
+  # saver module.
+  def load(readable, *options)
+    opthash = {
+      :format => :yaml,
+      :session => false,
+    }
+    case options.size
+    when 0
+    when 1
+      case options = options.first
+      when Symbol
+        opthash[:format] = options
+      else
+        opthash.update(options) if options
+      end
+    when 2
+      opthash[:format], options = options
+      opthash.update(options) if options
+    else
+      raise ArgumentError, 'wrong number of arguments (%d for 1-3)' % (1 + options.size)
     end
 
-    require 'yaml'
+    begin
+      saver = AbstractSaver.implementation(opthash[:format]).new(opthash)
+    rescue KeyError => e
+      raise ArgumentError, e.message
+    end
+
+    if readable.respond_to?(:write)
+      saver.load(readable, self)
+    else
+      File.open(readable, 'r') { |io|
+        saver.load(io, self)
+      }
+    end
+
+    self
   end
-  private :require_yaml
 
   # Clear the cookie jar and return self.
   def clear
@@ -161,26 +206,6 @@ class HTTP::CookieJar
     self
   end
 
-  # Read cookies from Mozilla cookies.txt-style IO stream and return
-  # self.
-  def load_cookiestxt(io)
-    io.each_line do |line|
-      c = HTTP::Cookie.parse_cookiestxt_line(line) and add(c)
-    end
-
-    self
-  end
-
-  # Write cookies to Mozilla cookies.txt-style IO stream and return
-  # self.
-  def dump_cookiestxt(io)
-    io.puts "# HTTP Cookie File"
-    to_a.each do |cookie|
-      io.print cookie.to_cookiestxt_line
-    end
-    self
-  end
-
   protected
 
   # Remove expired cookies and return self.
diff --git a/lib/http/cookie_jar/abstract_saver.rb b/lib/http/cookie_jar/abstract_saver.rb
new file mode 100644
index 0000000..af5a706
--- /dev/null
+++ b/lib/http/cookie_jar/abstract_saver.rb
@@ -0,0 +1,53 @@
+require 'http/cookie_jar'
+
+class HTTP::CookieJar::AbstractSaver
+  class << self
+    @@class_map = {}
+
+    # Gets an implementation class by the name, optionally trying to
+    # load "http/cookie_jar/*_saver" if not found.  If loading fails,
+    # KeyError is raised.
+    def implementation(symbol)
+      @@class_map.fetch(symbol)
+    rescue KeyError
+      begin
+        require 'http/cookie_jar/%s_saver' % symbol
+        @@class_map.fetch(symbol)
+      rescue LoadError, KeyError => e
+        raise KeyError, 'cookie saver unavailable: %s' % symbol.inspect
+      end
+    end
+
+    def inherited(subclass)
+      @@class_map[class_to_symbol(subclass)] = subclass
+    end
+
+    def class_to_symbol(klass)
+      klass.name[/[^:]+?(?=Saver$|$)/].downcase.to_sym
+    end
+  end
+
+  def default_options
+    {}
+  end
+  private :default_options
+
+  def initialize(options = nil)
+    options ||= {}
+    @logger  = options[:logger]
+    @session = options[:session]
+    # Initializes each instance variable of the same name as option
+    # keyword.
+    default_options.each_pair { |key, default|
+      instance_variable_set("@#{key}", options.key?(key) ? options[key] : default)
+    }
+  end
+
+  def save(io, jar)
+    raise
+  end
+
+  def load(io, jar)
+    raise
+  end
+end
diff --git a/lib/http/cookie_jar/cookiestxt_saver.rb b/lib/http/cookie_jar/cookiestxt_saver.rb
new file mode 100644
index 0000000..442af14
--- /dev/null
+++ b/lib/http/cookie_jar/cookiestxt_saver.rb
@@ -0,0 +1,74 @@
+require 'http/cookie_jar'
+
+# CookiestxtSaver saves and loads cookies in the cookies.txt format.
+class HTTP::CookieJar::CookiestxtSaver < HTTP::CookieJar::AbstractSaver
+  True  = "TRUE"
+  False = "FALSE"
+
+  def save(io, jar)
+    io.puts @header if @header
+    jar.each { |cookie|
+      next if !@session && cookie.session?
+      io.print cookie_to_record(cookie)
+    }
+  end
+
+  def load(io, jar)
+    io.each_line { |line|
+      cookie = parse_record(line) and jar.add(cookie)
+    }
+  end
+
+  private
+
+  def default_options
+    {
+      header: "# HTTP Cookie File",
+      linefeed: "\n",
+    }
+  end
+
+  # Serializes the cookie into a cookies.txt line.
+  def cookie_to_record(cookie)
+    cookie.instance_eval {
+      [
+        @domain,
+        @for_domain ? True : False,
+        @path,
+        @secure ? True : False,
+        @expires.to_i,
+        @name,
+        @value
+      ]
+    }.join("\t") << @linefeed
+  end
+
+  # Parses a line from cookies.txt and returns a cookie object if the
+  # line represents a cookie record or returns nil otherwise.
+  def parse_record(line)
+    return nil if line.match(/^#/)
+
+    domain,
+    s_for_domain,	# Whether this cookie is for domain
+    path,		# Path for which the cookie is relevant
+    s_secure,		# Requires a secure connection
+    s_expires,		# Time the cookie expires (Unix epoch time)
+    name, value = line.split("\t", 7)
+    return nil if value.nil?
+
+    value.chomp!
+
+    if (expires_seconds = s_expires.to_i).nonzero?
+      expires = Time.at(expires_seconds)
+      return nil if expires < Time.now
+    end
+
+    HTTP::Cookie.new(name, value,
+      :domain => domain,
+      :for_domain => s_for_domain == True,
+      :path => path,
+      :secure => s_secure == True,
+      :expires => expires,
+      :version => 0)
+  end
+end
diff --git a/lib/http/cookie_jar/yaml_saver.rb b/lib/http/cookie_jar/yaml_saver.rb
new file mode 100644
index 0000000..a9f66b5
--- /dev/null
+++ b/lib/http/cookie_jar/yaml_saver.rb
@@ -0,0 +1,30 @@
+require 'http/cookie_jar'
+begin
+  require 'psych'
+rescue LoadError
+end
+require 'yaml'
+
+# YAMLSaver saves and loads cookies in the YAML format.
+class HTTP::CookieJar::YAMLSaver < HTTP::CookieJar::AbstractSaver
+  def save(io, jar)
+    YAML.dump(@session ? jar.to_a : jar.reject(&:session?), io)
+  end
+
+  def load(io, jar)
+    begin
+      YAML.load(io)
+    rescue ArgumentError
+      @logger.warn "incompatible YAML cookie data discarded" if @logger
+      return
+    end.each { |cookie|
+      jar.add(cookie)
+    }
+  end
+
+  private
+
+  def default_options
+    {}
+  end
+end
diff --git a/test/test_http_cookie_jar.rb b/test/test_http_cookie_jar.rb
index 75cd2a8..467276d 100644
--- a/test/test_http_cookie_jar.rb
+++ b/test/test_http_cookie_jar.rb
@@ -301,7 +301,7 @@ class TestHTTPCookieJar < Test::Unit::TestCase
     assert_equal(3, @jar.cookies(url).length)
 
     in_tmpdir do
-      value = @jar.save_as("cookies.yml")
+      value = @jar.save("cookies.yml")
       assert_same @jar, value
 
       jar = HTTP::CookieJar.new
@@ -333,7 +333,7 @@ class TestHTTPCookieJar < Test::Unit::TestCase
     assert_equal(3, @jar.cookies(url).length)
 
     in_tmpdir do
-      @jar.save_as("cookies.yml", :format => :yaml, :session => true)
+      @jar.save("cookies.yml", :format => :yaml, :session => true)
 
       jar = HTTP::CookieJar.new
       jar.load("cookies.yml")
@@ -365,7 +365,7 @@ class TestHTTPCookieJar < Test::Unit::TestCase
     assert_equal(3, @jar.cookies(url).length)
 
     in_tmpdir do
-      @jar.save_as("cookies.txt", :cookiestxt)
+      @jar.save("cookies.txt", :cookiestxt)
 
       jar = HTTP::CookieJar.new
       jar.load("cookies.txt", :cookiestxt) # HACK test the format