diff --git a/Gemfile b/Gemfile
index 0b53433..50e1b75 100644
--- a/Gemfile
+++ b/Gemfile
@@ -1,6 +1,7 @@
 source 'https://rubygems.org/'
 
-gemspec
+gemspec name: 'multimeter'
+gemspec name: 'multimeter-http'
 
 group :examples do
   gem 'rack'
diff --git a/Rakefile b/Rakefile
index 4a76554..bf79ba7 100644
--- a/Rakefile
+++ b/Rakefile
@@ -14,7 +14,7 @@ Rake::JavaExtensionTask.new('multimeter_metrics') do |ext|
 end
 
 namespace :bundler do
-  Bundler::GemHelper.install_tasks
+  Bundler::GemHelper.install_tasks(name: 'multimeter')
 end
 
 task :release => [:spec, :compile, 'bundler:release']
diff --git a/ext/java/MultimeterMetricsService.java b/ext/java/MultimeterMetricsService.java
index 7c53adf..808dc72 100644
--- a/ext/java/MultimeterMetricsService.java
+++ b/ext/java/MultimeterMetricsService.java
@@ -10,6 +10,7 @@
 import multimeter.Histogram;
 import multimeter.Snapshot;
 import multimeter.Gauge;
+import multimeter.JSONSerializer;
 
 public class MultimeterMetricsService implements BasicLibraryService {
   public boolean basicLoad(final Ruby runtime) throws IOException {
@@ -20,6 +21,7 @@ public boolean basicLoad(final Ruby runtime) throws IOException {
     Histogram.setup(runtime);
     Snapshot.setup(runtime);
     Gauge.setup(runtime);
+    JSONSerializer.setup(runtime);
     return true;
   }
 }
diff --git a/ext/java/multimeter/Counter.java b/ext/java/multimeter/Counter.java
index 1339b7d..d819ab4 100644
--- a/ext/java/multimeter/Counter.java
+++ b/ext/java/multimeter/Counter.java
@@ -6,12 +6,14 @@
 import org.jruby.RubyObject;
 import org.jruby.RubyHash;
 import org.jruby.RubyArray;
+import org.jruby.RubyString;
 import org.jruby.anno.JRubyClass;
 import org.jruby.anno.JRubyMethod;
 import org.jruby.runtime.Block;
 import org.jruby.runtime.ObjectAllocator;
 import org.jruby.runtime.ThreadContext;
 import org.jruby.runtime.builtin.IRubyObject;
+import org.jruby.javasupport.JavaUtil;
 
 import static org.jruby.runtime.Visibility.PRIVATE;
 
@@ -30,6 +32,16 @@ public Counter(Ruby runtime, com.codahale.metrics.Counter counter) {
     this.counter = counter;
   }
 
+  @JRubyMethod(name="to_java")
+  public IRubyObject toJava(ThreadContext ctx) {
+    return JavaUtil.convertJavaToUsableRubyObject(ctx.runtime, counter);
+  }
+
+  @JRubyMethod(name="to_json")
+  public RubyString toJson(ThreadContext ctx) {
+    return JSONSerializer.getInstance().serialize(ctx, counter);
+  }
+
   @JRubyMethod
   public IRubyObject count(ThreadContext ctx) {
     return ctx.runtime.newFixnum(counter.getCount());
diff --git a/ext/java/multimeter/Gauge.java b/ext/java/multimeter/Gauge.java
index 85167e9..f2402e4 100644
--- a/ext/java/multimeter/Gauge.java
+++ b/ext/java/multimeter/Gauge.java
@@ -6,6 +6,7 @@
 import org.jruby.RubyObject;
 import org.jruby.RubyHash;
 import org.jruby.RubyArray;
+import org.jruby.RubyString;
 import org.jruby.anno.JRubyClass;
 import org.jruby.anno.JRubyMethod;
 import org.jruby.runtime.Block;
@@ -31,6 +32,16 @@ public Gauge(Ruby runtime, com.codahale.metrics.Gauge<? extends Object> gauge) {
     this.gauge = gauge;
   }
 
+  @JRubyMethod(name="to_java")
+  public IRubyObject toJava(ThreadContext ctx) {
+    return JavaUtil.convertJavaToUsableRubyObject(ctx.runtime, gauge);
+  }
+
+  @JRubyMethod(name="to_json")
+  public RubyString toJson(ThreadContext ctx) {
+    return JSONSerializer.getInstance().serialize(ctx, gauge);
+  }
+
   @JRubyMethod
   public IRubyObject value(ThreadContext ctx) {
     Object value = gauge.getValue();
diff --git a/ext/java/multimeter/Histogram.java b/ext/java/multimeter/Histogram.java
index fcc913d..0d554b3 100644
--- a/ext/java/multimeter/Histogram.java
+++ b/ext/java/multimeter/Histogram.java
@@ -6,12 +6,14 @@
 import org.jruby.RubyObject;
 import org.jruby.RubyHash;
 import org.jruby.RubyArray;
+import org.jruby.RubyString;
 import org.jruby.anno.JRubyClass;
 import org.jruby.anno.JRubyMethod;
 import org.jruby.runtime.Block;
 import org.jruby.runtime.ObjectAllocator;
 import org.jruby.runtime.ThreadContext;
 import org.jruby.runtime.builtin.IRubyObject;
+import org.jruby.javasupport.JavaUtil;
 
 import static org.jruby.runtime.Visibility.PRIVATE;
 
@@ -30,6 +32,16 @@ public Histogram(Ruby runtime, com.codahale.metrics.Histogram histogram) {
     this.histogram = histogram;
   }
 
+  @JRubyMethod(name="to_java")
+  public IRubyObject toJava(ThreadContext ctx) {
+    return JavaUtil.convertJavaToUsableRubyObject(ctx.runtime, histogram);
+  }
+
+  @JRubyMethod(name="to_json")
+  public RubyString toJson(ThreadContext ctx) {
+    return JSONSerializer.getInstance().serialize(ctx, histogram);
+  }
+
   @JRubyMethod
   public IRubyObject count(ThreadContext ctx) {
     return ctx.runtime.newFixnum(histogram.getCount());
diff --git a/ext/java/multimeter/JSONSerializer.java b/ext/java/multimeter/JSONSerializer.java
new file mode 100644
index 0000000..3e53849
--- /dev/null
+++ b/ext/java/multimeter/JSONSerializer.java
@@ -0,0 +1,55 @@
+package multimeter;
+
+import com.codahale.metrics.json.MetricsModule;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.util.concurrent.TimeUnit;
+import org.jruby.Ruby;
+import org.jruby.RubyClass;
+import org.jruby.RubyException;
+import org.jruby.exceptions.RaiseException;
+import org.jruby.RubyModule;
+import org.jruby.RubyString;
+import org.jruby.anno.JRubyClass;
+import org.jruby.runtime.ThreadContext;
+
+public class JSONSerializer {
+  private ObjectMapper mapper;
+  private MetricsModule module;
+
+  public static void setup(Ruby runtime) {
+    RubyModule multimeterModule = runtime.defineModule("Multimeter");
+    RubyClass standardError = runtime.getStandardError();
+    multimeterModule.defineClassUnder("JSONError", standardError, standardError.getAllocator());
+  }
+
+  @JRubyClass(name="Multimeter::JSONError", parent="StandardError")
+  public static class JSONError {}
+
+  private static JSONSerializer instance;
+
+  public static JSONSerializer getInstance() {
+    if ( instance == null ) {
+      instance = new JSONSerializer();
+    }
+    return instance;
+  }
+
+  private JSONSerializer() {
+    this.mapper = new ObjectMapper();
+    this.module = new MetricsModule(TimeUnit.SECONDS, TimeUnit.MILLISECONDS, false);
+    mapper.registerModule(module);
+  }
+
+  public RubyString serialize(ThreadContext ctx, Object object) {
+    ByteArrayOutputStream stream = new ByteArrayOutputStream();
+    try {
+      mapper.writeValue(stream, object);
+      return RubyString.newString(ctx.runtime, stream.toByteArray());
+    } catch (IOException e) {
+      RubyClass jsonError = ctx.runtime.getModule("Multimeter").getClass("JSONError");
+      throw new RaiseException(RubyException.newException(ctx.runtime, jsonError, e.toString()), false);
+    }
+  }
+}
\ No newline at end of file
diff --git a/ext/java/multimeter/Meter.java b/ext/java/multimeter/Meter.java
index 1fff410..2290527 100644
--- a/ext/java/multimeter/Meter.java
+++ b/ext/java/multimeter/Meter.java
@@ -6,12 +6,14 @@
 import org.jruby.RubyObject;
 import org.jruby.RubyHash;
 import org.jruby.RubyArray;
+import org.jruby.RubyString;
 import org.jruby.anno.JRubyClass;
 import org.jruby.anno.JRubyMethod;
 import org.jruby.runtime.Block;
 import org.jruby.runtime.ObjectAllocator;
 import org.jruby.runtime.ThreadContext;
 import org.jruby.runtime.builtin.IRubyObject;
+import org.jruby.javasupport.JavaUtil;
 
 import static org.jruby.runtime.Visibility.PRIVATE;
 
@@ -30,6 +32,16 @@ public Meter(Ruby runtime, com.codahale.metrics.Meter meter) {
     this.meter = meter;
   }
 
+  @JRubyMethod(name="to_java")
+  public IRubyObject toJava(ThreadContext ctx) {
+    return JavaUtil.convertJavaToUsableRubyObject(ctx.runtime, meter);
+  }
+
+  @JRubyMethod(name="to_json")
+  public RubyString toJson(ThreadContext ctx) {
+    return JSONSerializer.getInstance().serialize(ctx, meter);
+  }
+
   @JRubyMethod
   public IRubyObject count(ThreadContext ctx) {
     return ctx.runtime.newFixnum(meter.getCount());
diff --git a/ext/java/multimeter/MetricRegistry.java b/ext/java/multimeter/MetricRegistry.java
index bd8fbc8..b042f72 100644
--- a/ext/java/multimeter/MetricRegistry.java
+++ b/ext/java/multimeter/MetricRegistry.java
@@ -49,6 +49,11 @@ public IRubyObject toJava(ThreadContext ctx) {
     return JavaUtil.convertJavaToUsableRubyObject(ctx.runtime, registry);
   }
 
+  @JRubyMethod(name="to_json")
+  public RubyString toJson(ThreadContext ctx) {
+    return JSONSerializer.getInstance().serialize(ctx, registry);
+  }
+
   @JRubyMethod
   public IRubyObject metrics(ThreadContext ctx) {
     return metrics.dup(ctx);
diff --git a/ext/java/multimeter/Snapshot.java b/ext/java/multimeter/Snapshot.java
index f3ba09c..f68c30e 100644
--- a/ext/java/multimeter/Snapshot.java
+++ b/ext/java/multimeter/Snapshot.java
@@ -6,12 +6,14 @@
 import org.jruby.RubyObject;
 import org.jruby.RubyHash;
 import org.jruby.RubyArray;
+import org.jruby.RubyString;
 import org.jruby.anno.JRubyClass;
 import org.jruby.anno.JRubyMethod;
 import org.jruby.runtime.Block;
 import org.jruby.runtime.ObjectAllocator;
 import org.jruby.runtime.ThreadContext;
 import org.jruby.runtime.builtin.IRubyObject;
+import org.jruby.javasupport.JavaUtil;
 
 import static org.jruby.runtime.Visibility.PRIVATE;
 
@@ -30,6 +32,16 @@ public Snapshot(Ruby runtime, com.codahale.metrics.Snapshot snapshot) {
     this.snapshot = snapshot;
   }
 
+  @JRubyMethod(name="to_java")
+  public IRubyObject toJava(ThreadContext ctx) {
+    return JavaUtil.convertJavaToUsableRubyObject(ctx.runtime, snapshot);
+  }
+
+  @JRubyMethod(name="to_json")
+  public RubyString toJson(ThreadContext ctx) {
+    return JSONSerializer.getInstance().serialize(ctx, snapshot);
+  }
+
   @JRubyMethod
   public IRubyObject size(ThreadContext ctx) {
     return ctx.runtime.newFixnum(snapshot.size());
diff --git a/ext/java/multimeter/Timer.java b/ext/java/multimeter/Timer.java
index 7b0e177..5b06758 100644
--- a/ext/java/multimeter/Timer.java
+++ b/ext/java/multimeter/Timer.java
@@ -6,12 +6,14 @@
 import org.jruby.RubyObject;
 import org.jruby.RubyHash;
 import org.jruby.RubyArray;
+import org.jruby.RubyString;
 import org.jruby.anno.JRubyClass;
 import org.jruby.anno.JRubyMethod;
 import org.jruby.runtime.Block;
 import org.jruby.runtime.ObjectAllocator;
 import org.jruby.runtime.ThreadContext;
 import org.jruby.runtime.builtin.IRubyObject;
+import org.jruby.javasupport.JavaUtil;
 
 import static org.jruby.runtime.Visibility.PRIVATE;
 
@@ -35,6 +37,16 @@ public Timer(Ruby runtime, com.codahale.metrics.Timer timer) {
     this.timer = timer;
   }
 
+  @JRubyMethod(name="to_java")
+  public IRubyObject toJava(ThreadContext ctx) {
+    return JavaUtil.convertJavaToUsableRubyObject(ctx.runtime, timer);
+  }
+
+  @JRubyMethod(name="to_json")
+  public RubyString toJson(ThreadContext ctx) {
+    return JSONSerializer.getInstance().serialize(ctx, timer);
+  }
+
   @JRubyMethod
   public IRubyObject count(ThreadContext ctx) {
     return ctx.runtime.newFixnum(timer.getCount());
diff --git a/lib/multimeter.rb b/lib/multimeter.rb
index a40aeb3..28c2a18 100644
--- a/lib/multimeter.rb
+++ b/lib/multimeter.rb
@@ -1,95 +1,16 @@
 # encoding: utf-8
 
 require 'metrics-core-jars'
+require 'metrics-json-jars'
 require 'multimeter_metrics'
-require 'json'
+require 'multimeter/rack'
 
 module Metrics
   include_package 'com.codahale.metrics'
 end
 
 module Multimeter
-  class MetricRegistry
-    def to_h
-      h = {}
-      metrics.each do |metric_name, metric|
-        h[metric_name] = metric.to_h
-      end
-      h
-    end
-  end
-
-  class Meter
-    def to_h
-      {
-        :type => :meter,
-        :count => count,
-        :mean_rate => mean_rate,
-        :one_minute_rate => one_minute_rate,
-        :five_minute_rate => five_minute_rate,
-        :fifteen_minute_rate => fifteen_minute_rate
-      }
-    end
-  end
-
-  class Counter
-    def to_h
-      {
-        :type => :counter,
-        :count => count
-      }
-    end
-  end
-
-  class Histogram
-    def to_h
-      {
-        :type => :histogram,
-        :count => count,
-      }.merge(snapshot.to_h(NANO_TO_MILLI_SCALE))
-    end
-  end
-
-  class Timer
-    def to_h
-      {
-        :type => :timer,
-        :count => count,
-        :mean_rate => mean_rate,
-        :one_minute_rate => one_minute_rate,
-        :five_minute_rate => five_minute_rate,
-        :fifteen_minute_rate => fifteen_minute_rate,
-      }.merge(snapshot.to_h(NANO_TO_MILLI_SCALE))
-    end
-  end
-
-  class Snapshot
-    def to_h(scale=1)
-      {
-        :max => max * scale,
-        :min => min * scale,
-        :mean => mean * scale,
-        :std_dev => std_dev * scale,
-        :median => median * scale,
-        :percentiles => {
-          '75' => p75 * scale,
-          '95' => p95 * scale,
-          '98' => p98 * scale,
-          '99' => p99 * scale,
-          '99.9' => p999 * scale,
-        }
-      }
-    end
-  end
-
-  class Gauge
-    def to_h
-      {
-        :type => :gauge,
-        :value => value,
-      }
-    end
-  end
+  extend Rack
 
   def self.create_registry
     MetricRegistry.new
@@ -98,51 +19,4 @@ def self.create_registry
   def self.jmx(registry, options = {})
     Metrics::JmxReporter.forRegistry(registry.to_java).inDomain(options[:domain] || 'multimeter').build.tap(&:start)
   end
-
-  def self.http(registry, rack_handler, options={})
-    server_thread = Java::JavaLang::Thread.new do
-      rack_handler.run(Http.create_app(registry), options)
-    end
-    server_thread.daemon = true
-    server_thread.name = 'multimeter-http-server'
-    server_thread.start
-    server_thread
-  end
-
-  private
-
-  NANO_TO_MILLI_SCALE = 1.0/1_000_000
-
-  module Http
-    class BadRequest < StandardError; end
-
-    COMMON_HEADERS = {'Connection' => 'close'}.freeze
-    JSON_HEADERS = COMMON_HEADERS.merge('Content-Type' => 'application/json').freeze
-    JSONP_HEADERS = COMMON_HEADERS.merge('Content-Type' => 'application/javascript').freeze
-    ERROR_HEADERS = COMMON_HEADERS.merge('Content-Type' => 'text/plain').freeze
-
-    def self.create_app(registry)
-      proc do |env|
-        begin
-          body = registry.to_h.to_json
-          headers = JSON_HEADERS
-          if (callback_name = env['QUERY_STRING'][/callback=([^$&]+)/, 1])
-            if callback_name =~ /^[\w\d.]+$/
-              body = "#{callback_name}(#{body});"
-              headers = JSONP_HEADERS
-            else
-              raise BadRequest
-            end
-          else
-            headers = headers.merge('Access-Control-Allow-Origin' => '*')
-          end
-          [200, headers, [body]]
-        rescue BadRequest => e
-          [400, ERROR_HEADERS, ['Bad Request']]
-        rescue => e
-          [500, ERROR_HEADERS, ["Internal Server Error\n\n", e.message, "\n\t", *e.backtrace.join("\n\t")]]
-        end
-      end
-    end
-  end
 end
diff --git a/lib/multimeter/http.rb b/lib/multimeter/http.rb
new file mode 100644
index 0000000..601355c
--- /dev/null
+++ b/lib/multimeter/http.rb
@@ -0,0 +1,58 @@
+# encoding: utf-8
+
+require 'multimeter'
+require 'metrics-servlets-jars'
+require 'rjack-jetty'
+
+module Metrics
+  module Servlets
+    include_package 'com.codahale.metrics.servlets'
+  end
+end
+
+module Jetty
+  include_package 'org.eclipse.jetty.server'
+  include_package 'org.eclipse.jetty.servlet'
+end
+
+module Multimeter
+  module Http
+    def http(registry, options={})
+      server = Jetty::Server.new(options[:port] || 5747)
+      server.handler = create_servlet_context(registry)
+      Server.new(server)
+    end
+
+    private
+
+    def create_servlet_context(registry)
+      context = Jetty::ServletContextHandler.new(Jetty::ServletContextHandler::SESSIONS)
+      context.context_path = '/'
+      context.set_attribute(Metrics::Servlets::MetricsServlet::METRICS_REGISTRY, registry.to_java)
+      context.add_servlet(Metrics::Servlets::MetricsServlet.java_class, '/*')
+      context
+    end
+
+    class Server
+      def initialize(server)
+        @server = server
+      end
+
+      def start
+        @server.start
+        self
+      end
+
+      def stop
+        @server.stop
+        self
+      end
+
+      def join
+        @server.join
+      end
+    end
+  end
+
+  extend Http
+end
diff --git a/lib/multimeter/rack.rb b/lib/multimeter/rack.rb
new file mode 100644
index 0000000..746311b
--- /dev/null
+++ b/lib/multimeter/rack.rb
@@ -0,0 +1,41 @@
+# encoding: utf-8
+
+module Multimeter
+  module Rack
+    class BadRequest < StandardError; end
+
+    COMMON_HEADERS = {'Connection' => 'close'}.freeze
+    JSON_HEADERS = COMMON_HEADERS.merge('Content-Type' => 'application/json', 'Access-Control-Allow-Origin' => '*').freeze
+    JSONP_HEADERS = COMMON_HEADERS.merge('Content-Type' => 'application/javascript').freeze
+    ERROR_HEADERS = COMMON_HEADERS.merge('Content-Type' => 'text/plain').freeze
+
+    class App
+      def initialize(registry)
+        @registry = registry
+      end
+
+      def call(env)
+        if (callback_name = env['QUERY_STRING'][/callback=([^$&]+)/, 1])
+          if callback_name =~ /^[\w\d.]+$/
+            body = "#{callback_name}(#{@registry.to_json});"
+            headers = JSONP_HEADERS
+          else
+            raise BadRequest
+          end
+        else
+          headers = JSON_HEADERS
+          body = @registry.to_json
+        end
+        [200, headers, [body]]
+      rescue BadRequest => e
+        [400, ERROR_HEADERS, ['Bad Request']]
+      rescue => e
+        [500, ERROR_HEADERS, ["Internal Server Error\n\n", e.message, "\n\t", *e.backtrace.join("\n\t")]]
+      end
+    end
+
+    def create_app(registry)
+      App.new(registry)
+    end
+  end
+end
diff --git a/multimeter-http.gemspec b/multimeter-http.gemspec
new file mode 100644
index 0000000..811c102
--- /dev/null
+++ b/multimeter-http.gemspec
@@ -0,0 +1,23 @@
+$: << File.expand_path('../lib', __FILE__)
+
+require 'rake'
+require 'multimeter/version'
+
+Gem::Specification.new do |s|
+  s.name        = 'multimeter-http'
+  s.version     = Multimeter::VERSION
+  s.platform    = 'java'
+  s.authors     = ['Theo Hultberg', 'Joel Segerlind']
+  s.email       = ['theo@iconara.net', 'joel.segerlind@gmail.com']
+  s.homepage    = 'http://github.com/iconara/multimeter'
+  s.summary     = 'Multimeter addition for serving metrics over HTTP'
+  s.description = 'Multimeter addition for serving metrics over HTTP, using Dropwizard\'s (a.k.a. Coda Hale\'s) Metrics libraries under the hood.'
+  s.license     = 'Apache-2.0'
+
+  s.add_dependency 'multimeter', "= #{Multimeter::VERSION}"
+  s.add_dependency 'metrics-servlets-jars', '~> 3.1'
+  s.add_dependency 'rjack-jetty', '~> 9.2.12'
+
+  s.files         = Dir['lib/multimeter/http.rb']
+  s.require_paths = %w[lib]
+end
diff --git a/multimeter.gemspec b/multimeter.gemspec
index c2e2a73..6d5cf1a 100644
--- a/multimeter.gemspec
+++ b/multimeter.gemspec
@@ -18,7 +18,8 @@ Gem::Specification.new do |s|
   s.rubyforge_project = 'multimeter'
 
   s.add_dependency 'metrics-core-jars', '~> 3.1', '< 4.0.0'
+  s.add_dependency 'metrics-json-jars', '~> 3.1'
 
-  s.files         = Dir['lib/**/*.rb', 'lib/**/*.jar']
+  s.files         = %w[lib/multimeter.rb lib/multimeter_metrics.jar lib/multimeter/json.rb lib/multimeter/rack.rb]
   s.require_paths = %w[lib]
 end
diff --git a/spec/integration/http_spec.rb b/spec/integration/http_spec.rb
new file mode 100644
index 0000000..f2c566b
--- /dev/null
+++ b/spec/integration/http_spec.rb
@@ -0,0 +1,45 @@
+# encoding: utf-8
+
+require 'spec_helper'
+require 'open-uri'
+require 'support/json_metrics'
+
+module Multimeter
+  describe Http do
+    let :registry do
+      MetricRegistry.new
+    end
+
+    let :port do
+      loop do
+        port = rand(1024...2**15)
+        begin
+          TCPSocket.new('localhost', port).close
+        rescue Errno::ECONNREFUSED
+          return port
+        end
+      end
+    end
+
+    let :server do
+      Multimeter.http(registry, port: port)
+    end
+
+    before do
+      server.start
+    end
+
+    after do
+      server.stop
+      server.join
+    end
+
+    describe 'GET /' do
+      let :json do
+        open("http://localhost:#{port}").read
+      end
+
+      include_examples 'json-metrics'
+    end
+  end
+end
\ No newline at end of file
diff --git a/spec/multimeter/counter_spec.rb b/spec/multimeter/counter_spec.rb
index ba3ed2e..26e6d3c 100644
--- a/spec/multimeter/counter_spec.rb
+++ b/spec/multimeter/counter_spec.rb
@@ -34,13 +34,10 @@ module Multimeter
       end
     end
 
-    describe '#to_h' do
-      it 'returns a hash representation of the counter' do
+    describe '#to_json' do
+      it 'returns a json representation of the counter' do
         counter.inc
-        expect(counter.to_h).to eq(
-          :type => :counter,
-          :count => 1
-        )
+        expect(JSON.parse(counter.to_json)).to include('count' => 1)
       end
     end
   end
diff --git a/spec/multimeter/gauge_spec.rb b/spec/multimeter/gauge_spec.rb
index 3be0e13..b9424da 100644
--- a/spec/multimeter/gauge_spec.rb
+++ b/spec/multimeter/gauge_spec.rb
@@ -5,7 +5,7 @@
 module Multimeter
   describe Gauge do
     let :gauge do
-      MetricRegistry.new.gauge('a_gauge') { @value }
+      MetricRegistry.new.gauge('a_gauge', :int) { @value }
     end
 
     before do
@@ -20,12 +20,19 @@ module Multimeter
       end
     end
 
-    describe '#to_h' do
-      it 'returns a hash representation of the gauge' do
-        expect(gauge.to_h).to eq(
-          :type => :gauge,
-          :value => 3
-        )
+    describe '#to_json' do
+      it 'returns a json representation of the gauge' do
+        expect(JSON.parse(gauge.to_json)).to include('value' => 3)
+      end
+
+      context 'when the gauge is untyped' do
+        let :gauge do
+          MetricRegistry.new.gauge('b_gauge') { 1 }
+        end
+
+        it 'raises JsonError' do
+          expect { gauge.to_json }.to raise_error(JSONError)
+        end
       end
     end
   end
diff --git a/spec/multimeter/histogram_spec.rb b/spec/multimeter/histogram_spec.rb
index 51189ce..7712fc3 100644
--- a/spec/multimeter/histogram_spec.rb
+++ b/spec/multimeter/histogram_spec.rb
@@ -69,21 +69,22 @@ module Multimeter
       end
     end
 
-    it 'returns a hash representation of the histogram' do
-      histogram.update(4)
-      h = histogram.to_h
-      expect(h[:type]).to eq(:histogram)
-      expect(h[:count]).to eq(1)
-      expect(h[:max]).to be_a(Numeric)
-      expect(h[:min]).to be_a(Numeric)
-      expect(h[:mean]).to be_a(Numeric)
-      expect(h[:std_dev]).to be_a(Numeric)
-      expect(h[:median]).to be_a(Numeric)
-      expect(h[:percentiles]['75']).to be_a(Numeric)
-      expect(h[:percentiles]['95']).to be_a(Numeric)
-      expect(h[:percentiles]['98']).to be_a(Numeric)
-      expect(h[:percentiles]['99']).to be_a(Numeric)
-      expect(h[:percentiles]['99.9']).to be_a(Numeric)
+    describe '#to_json' do
+      it 'returns a json representation of the histogram' do
+        histogram.update(4)
+        expect(JSON.parse(histogram.to_json)).to include(
+          'count' => 1,
+          'max' => 4.0,
+          'min' => 4.0,
+          'mean' => 4.0,
+          'stddev' => 0.0,
+          'p50' => 4.0,
+          'p75' => 4.0,
+          'p95' => 4.0,
+          'p99' => 4.0,
+          'p999' => 4.0,
+        )
+      end
     end
   end
 end
diff --git a/spec/multimeter/meter_spec.rb b/spec/multimeter/meter_spec.rb
index ec031be..dd98524 100644
--- a/spec/multimeter/meter_spec.rb
+++ b/spec/multimeter/meter_spec.rb
@@ -42,16 +42,16 @@ module Multimeter
       end
     end
 
-    describe '#to_h' do
-      it 'returns a hash representation of the meter' do
+    describe '#to_json' do
+      it 'returns a json representation of the meter' do
         meter.mark
-        h = meter.to_h
-        expect(h[:type]).to eq(:meter)
-        expect(h[:count]).to eq(1)
-        expect(h[:mean_rate]).to be_a(Numeric)
-        expect(h[:one_minute_rate]).to be_a(Numeric)
-        expect(h[:five_minute_rate]).to be_a(Numeric)
-        expect(h[:fifteen_minute_rate]).to be_a(Numeric)
+        expect(JSON.parse(meter.to_json)).to include(
+          'count' => 1,
+          'mean_rate' => be_a(Numeric),
+          'm1_rate' => be_a(Numeric),
+          'm5_rate' => be_a(Numeric),
+          'm15_rate' => be_a(Numeric),
+        )
       end
     end
   end
diff --git a/spec/multimeter/metric_registry_spec.rb b/spec/multimeter/metric_registry_spec.rb
index cf711c9..d17dbb5 100644
--- a/spec/multimeter/metric_registry_spec.rb
+++ b/spec/multimeter/metric_registry_spec.rb
@@ -159,17 +159,21 @@ module Multimeter
       end
     end
 
-    describe '#to_h' do
-      it 'returns a hash representing all the metrics' do
+    describe '#to_json' do
+      it 'returns a json representing all the metrics' do
         metric_registry.counter('a_counter')
         metric_registry.meter('a_meter')
         metric_registry.timer('a_timer')
         metric_registry.histogram('an_histogram')
-        metric_registry.gauge('a_gauge') { 3 }
-        h = metric_registry.to_h
-        expect(h.keys).to contain_exactly(*%w[a_counter a_meter a_timer an_histogram a_gauge])
-        h.each do |key, value|
-          expect(value).to eq(metric_registry.metrics[key].to_h)
+        metric_registry.gauge('a_gauge', :int) { 3 }
+        h = JSON.parse(metric_registry.to_json)
+        metric_types = %w[counters meters timers histograms gauges]
+        expect(h.keys).to match_array(metric_types + ['version'])
+        metric_types.each do |type|
+          metrics = h[type]
+          metrics.each do |name, value|
+            expect(value).to eq(JSON.parse(metric_registry.metrics[name].to_json))
+          end
         end
       end
     end
diff --git a/spec/multimeter/http_spec.rb b/spec/multimeter/rack_spec.rb
similarity index 53%
rename from spec/multimeter/http_spec.rb
rename to spec/multimeter/rack_spec.rb
index dcf5b41..8e08fa0 100644
--- a/spec/multimeter/http_spec.rb
+++ b/spec/multimeter/rack_spec.rb
@@ -1,72 +1,67 @@
 # encoding: utf-8
 
 require 'spec_helper'
+require 'support/json_metrics'
 
 module Multimeter
-  describe 'Multimeter.http' do
+  describe 'Multimeter.create_app' do
     let :registry do
       Multimeter.create_registry
     end
 
-    context 'when handling requests' do
-      def extract_app
-        barrier = java.util.concurrent.Semaphore.new(0)
-        app, options = nil, nil
-        rack_handler = double(:rack_handler)
-        allow(rack_handler).to receive(:run) do |a, o|
-          app, options = a, o
-          barrier.release
-        end
-        Multimeter.http(registry, rack_handler)
-        expect(barrier.try_acquire(5, java.util.concurrent.TimeUnit::SECONDS)).not_to be_falsy
-        [app, options]
-      end
-
-      before do
-        registry.counter('test').inc
-      end
+    let :app do
+      Multimeter.create_app(registry)
+    end
 
+    context 'when handling' do
       context 'valid requests' do
-        it 'responds with a JSON document created from calling #to_h on the registry' do
-          app, options = extract_app
-          status, headers, body = app.call({'QUERY_STRING' => ''})
-          expect(body.join("\n")).to eq('{"test":{"type":"counter","count":1}}')
+        context 'responds with a JSON document that' do
+          let :json do
+            status, headers, body = app.call({'QUERY_STRING' => ''})
+            body.join
+          end
+
+          include_examples 'json-metrics'
         end
 
         it 'responds with application/json' do
-          app, options = extract_app
           status, headers, body = app.call({'QUERY_STRING' => ''})
           expect(headers).to include('Content-Type' => 'application/json')
         end
 
         it 'responds with Connection: close' do
-          app, options = extract_app
           status, headers, body = app.call({'QUERY_STRING' => ''})
           expect(headers).to include('Connection' => 'close')
         end
 
         it 'responds with CORS headers' do
-          app, _ = extract_app
           _, headers, _ = app.call({'QUERY_STRING' => ''})
           expect(headers).to include('Access-Control-Allow-Origin' => '*')
         end
 
-        context 'JSONP' do
-          it 'responds with a JSON document wrapped in a function call when the callback parameter is given' do
-            app, options = extract_app
-            status, headers, body = app.call({'QUERY_STRING' => 'callback=the_cbk'})
-            expect(body.join("\n")).to eq('the_cbk({"test":{"type":"counter","count":1}});')
+        context 'with a JSONP parameter' do
+          let :env do
+            { 'QUERY_STRING' => 'callback=the_cbk' }
+          end
+
+          it 'wraps the body in a function call' do
+            status, headers, body = app.call(env)
+            expect(body.join).to match(/\Athe_cbk\(.*\);\Z/)
+          end
+
+          it 'responds with a valid JSON document' do
+            status, headers, body = app.call(env)
+            json = body.join[/(?<=\Athe_cbk\().*(?=\);\Z)/]
+            expect { JSON.parse(json) }.not_to raise_error
           end
 
           it 'responds with application/javascript for JSONP request' do
-            app, options = extract_app
-            status, headers, body = app.call({'QUERY_STRING' => 'callback=the_cbk'})
+            status, headers, body = app.call(env)
             expect(headers).to include('Content-Type' => 'application/javascript')
           end
 
           it 'responds with Connection: close' do
-            app, options = extract_app
-            status, headers, body = app.call({'QUERY_STRING' => 'callback=the_cbk'})
+            status, headers, body = app.call(env)
             expect(headers).to include('Connection' => 'close')
           end
         end
@@ -75,29 +70,26 @@ def extract_app
       context 'invalid requests' do
         context '400' do
           it 'responds with error 400 if the callback contains invalid chars' do
-            app, options = extract_app
             status, headers, body = app.call({'QUERY_STRING' => 'callback=apa*&^%$'})
             expect(status).to eq(400)
           end
 
           it 'responds with Connection: close' do
-            app, options = extract_app
             status, headers, body = app.call({'QUERY_STRING' => 'callback=apa*&^%$'})
             expect(headers).to include('Connection' => 'close')
           end
         end
+
         context '500' do
           it 'responds with error 500 if an exception is thrown in the request handling' do
-            allow(registry).to receive(:to_h).and_raise('blurgh')
-            app, options = extract_app
-            status, headers, body = app.call({'QUERY_STRING' => 'callback=apa*&^%$'})
+            allow(registry).to receive(:to_json).and_raise('blurgh')
+            status, headers, body = app.call({'QUERY_STRING' => ''})
             expect(status).to eq(500)
           end
 
           it 'responds with Connection: close' do
-            allow(registry).to receive(:to_h).and_raise('blurgh')
-            app, options = extract_app
-            status, headers, body = app.call({'QUERY_STRING' => 'callback=apa*&^%$'})
+            allow(registry).to receive(:to_json).and_raise('blurgh')
+            status, headers, body = app.call({'QUERY_STRING' => ''})
             expect(headers).to include('Connection' => 'close')
           end
         end
diff --git a/spec/multimeter/timer_spec.rb b/spec/multimeter/timer_spec.rb
index 39ba2a7..b7c8d14 100644
--- a/spec/multimeter/timer_spec.rb
+++ b/spec/multimeter/timer_spec.rb
@@ -140,35 +140,25 @@ module Multimeter
       end
     end
 
-    describe '#to_h' do
+    describe '#to_json' do
       it 'returns a hash representation of the timer' do
         timer.update(100, :milliseconds)
-        h = timer.to_h
-        expect(h[:type]).to eq(:timer)
-        expect(h[:count]).to eq(1)
-        expect(h[:mean_rate]).to be_a(Numeric)
-        expect(h[:one_minute_rate]).to be_a(Numeric)
-        expect(h[:five_minute_rate]).to be_a(Numeric)
-        expect(h[:fifteen_minute_rate]).to be_a(Numeric)
-        expect(h[:max]).to be_a(Numeric)
-        expect(h[:min]).to be_a(Numeric)
-        expect(h[:mean]).to be_a(Numeric)
-        expect(h[:std_dev]).to be_a(Numeric)
-        expect(h[:median]).to be_a(Numeric)
-        expect(h[:percentiles]['75']).to be_a(Numeric)
-        expect(h[:percentiles]['95']).to be_a(Numeric)
-        expect(h[:percentiles]['98']).to be_a(Numeric)
-        expect(h[:percentiles]['99']).to be_a(Numeric)
-        expect(h[:percentiles]['99.9']).to be_a(Numeric)
-      end
-
-      it 'scales the durations to milliseconds' do
-        timer.update(1, :seconds)
-        h = timer.to_h
-        expect(h[:max]).to eq(1000.0)
-        expect(h[:min]).to eq(1000.0)
-        expect(h[:mean]).to eq(1000.0)
-        expect(h[:median]).to eq(1000.0)
+        expect(JSON.parse(timer.to_json)).to include(
+          'count' => 1,
+          'mean_rate' => be_a(Numeric),
+          'm1_rate' => be_a(Numeric),
+          'm5_rate' => be_a(Numeric),
+          'm15_rate' => be_a(Numeric),
+          'max' => 100.0,
+          'min' => 100.0,
+          'mean' => 100.0,
+          'stddev' => 0.0,
+          'p50' => 100.0,
+          'p75' => 100.0,
+          'p95' => 100.0,
+          'p99' => 100.0,
+          'p999' => 100.0,
+        )
       end
     end
   end
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index 94de6a6..f68008e 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -1,3 +1,5 @@
 require 'bundler/setup'
 require 'slf4j-jars'
+require 'json'
 require 'multimeter'
+require 'multimeter/http'
diff --git a/spec/support/json_metrics.rb b/spec/support/json_metrics.rb
new file mode 100644
index 0000000..9afbd33
--- /dev/null
+++ b/spec/support/json_metrics.rb
@@ -0,0 +1,120 @@
+require 'json'
+
+shared_examples 'json-metrics' do
+  let :metrics do
+    JSON.parse(json)
+  end
+
+  it 'returns JSON' do
+    expect { metrics }.not_to raise_error
+  end
+
+  shared_examples 'count' do
+    it 'includes count' do
+      expect(metric).to have_key('count')
+    end
+  end
+
+  shared_examples 'rates' do
+    {
+      'm1_rate' => 'one minute rate',
+      'm5_rate' => 'five minute rate',
+      'm15_rate' => 'fifteen minute rate',
+      'mean_rate' => 'mean rate',
+    }.each do |key, name|
+      it "includes the #{name}" do
+        expect(metric).to have_key(key)
+      end
+    end
+  end
+
+  shared_examples 'histogram' do
+    {
+      'p50' => '50th percentile',
+      'p75' => '75th percentile',
+      'p95' => '95th percentile',
+      'p98' => '98th percentile',
+      'p99' => '99th percentile',
+      'p999' => '99.9th percentile',
+      'min' => 'minimum value',
+      'max' => 'maximum value',
+      'mean' => 'mean value',
+      'stddev' => 'standard deviation',
+    }.each do |key, name|
+      it "includes the #{name}" do
+        expect(metric).to have_key(key)
+      end
+    end
+  end
+
+  context 'with counters' do
+    before do
+      registry.counter('spec-counter').inc
+    end
+
+    let :metric do
+      metrics['counters']['spec-counter']
+    end
+
+    include_examples 'count'
+  end
+
+  context 'with meters' do
+    before do
+      registry.meter('spec-meter').mark
+    end
+
+    let :metric do
+      metrics['meters']['spec-meter']
+    end
+
+    include_examples 'count'
+    include_examples 'rates'
+  end
+
+  context 'with histograms' do
+    before do
+      registry.histogram('spec-histogram').update(1)
+    end
+
+    let :metric do
+      metrics['histograms']['spec-histogram']
+    end
+
+    include_examples 'histogram'
+  end
+
+  context 'with timers' do
+    before do
+      registry.timer('spec-timer').time {}
+    end
+
+    let :metric do
+      metrics['timers']['spec-timer']
+    end
+
+    include_examples 'count'
+    include_examples 'rates'
+    include_examples 'histogram'
+  end
+
+  context 'with gauges' do
+    before do
+      registry.gauge('spec-gauge', :string) { 'a string' }
+    end
+
+    it 'inclues the value' do
+      expect(metrics['gauges']['spec-gauge']).to include('value' => 'a string')
+    end
+
+    context "when type isn't specified" do
+      before do
+        registry.gauge('untyped-gauge') { -1 }
+      end
+
+      it 'failes to serialize' do
+        expect { metrics }.to raise_error(JSON::ParserError)
+      end
+    end
+  end
+end
\ No newline at end of file