diff --git a/Gemfile b/Gemfile
index 3506a0e..8357cf1 100644
--- a/Gemfile
+++ b/Gemfile
@@ -4,3 +4,4 @@ gemspec
 group :test do
   gem 'rake'
 end
+gem 'rspec'
diff --git a/lib/json-diff.rb b/lib/json-diff.rb
index f1c10fd..83efeb5 100644
--- a/lib/json-diff.rb
+++ b/lib/json-diff.rb
@@ -1,4 +1,5 @@
 require 'json-diff/diff'
+require 'json-diff/v2/diff'
 require 'json-diff/index-map'
 require 'json-diff/operation'
 require 'json-diff/version'
diff --git a/lib/json-diff/v2/diff.rb b/lib/json-diff/v2/diff.rb
new file mode 100644
index 0000000..927e924
--- /dev/null
+++ b/lib/json-diff/v2/diff.rb
@@ -0,0 +1,150 @@
+module JsonDiff
+  class V2
+    attr_reader :opts, :changes
+
+    def self.diff(before, after, opts = {})
+      runner = new(opts)
+      runner.diff(before, after)
+      runner.changes
+    end
+
+    def initialize(opts = {})
+      @opts = opts
+      @changes  = []
+    end
+
+    def diff_hash(before, after, path)
+      lost = before.keys - after.keys
+      lost.each do |key|
+        inner_path = JsonDiff.extend_json_pointer(path, key)
+        changes << JsonDiff.remove(inner_path, include_was(path) ? before[key] : nil)
+      end
+
+      if include_addition(:hash, path)
+        gained = after.keys - before.keys
+        gained.each do |key|
+          inner_path = JsonDiff.extend_json_pointer(path, key)
+          changes << JsonDiff.add(inner_path, after[key])
+        end
+      end
+
+      kept = before.keys & after.keys
+      kept.each do |key|
+        inner_path = JsonDiff.extend_json_pointer(path, key)
+        diff(before[key], after[key], inner_path)
+      end
+    end
+
+    def diff_array(before, after, path)
+      if before.size == 0
+        if include_addition(:array, path)
+          after.each_with_index do |item, index|
+            inner_path = JsonDiff.extend_json_pointer(path, index)
+            changes << JsonDiff.add(inner_path, item)
+          end
+        end
+      elsif after.size == 0
+        before.each do |item|
+          # Delete elements from the start.
+          inner_path = JsonDiff.extend_json_pointer(path, 0)
+          changes << JsonDiff.remove(inner_path, include_was(path) ? item : nil)
+        end
+      else
+        pairing = JsonDiff.array_pairing(before, after, opts)
+        # FIXME: detect replacements.
+
+        # All detected moves that do not reach the similarity limit are deleted
+        # and re-added.
+        pairing[:pairs].select! do |pair|
+          sim = pair[2]
+          kept = (sim >= 0.5)
+          if !kept
+            pairing[:removed] << pair[0]
+            pairing[:added] << pair[1]
+          end
+          kept
+        end
+
+        pairing[:pairs].each do |pair|
+          before_index, after_index = pair
+          inner_path = JsonDiff.extend_json_pointer(path, before_index)
+          diff(before[before_index], after[after_index], inner_path)
+        end
+
+        if !original_indices(path)
+          # Recompute indices to account for offsets from insertions and
+          # deletions.
+          pairing = JsonDiff.array_changes(pairing)
+        end
+
+        pairing[:removed].each do |before_index|
+          inner_path = JsonDiff.extend_json_pointer(path, before_index)
+          changes << JsonDiff.remove(inner_path, include_was(path) ? before[before_index] : nil)
+        end
+
+        pairing[:pairs].each do |pair|
+          before_index, after_index = pair
+          inner_before_path = JsonDiff.extend_json_pointer(path, before_index)
+          inner_after_path = JsonDiff.extend_json_pointer(path, after_index)
+
+          if before_index != after_index && include_moves(path)
+            changes << JsonDiff.move(inner_before_path, inner_after_path)
+          end
+        end
+
+        if include_addition(:array, path)
+          pairing[:added].each do |after_index|
+            inner_path = JsonDiff.extend_json_pointer(path, after_index)
+            changes << JsonDiff.add(inner_path, after[after_index])
+          end
+        end
+      end
+    end
+
+    def diff(before, after, path = '')
+      if before.is_a?(Hash)
+        if !after.is_a?(Hash)
+          changes << JsonDiff.replace(path, include_was(path) ? before : nil, after) if include_replace(path)
+        else
+          diff_hash(before, after, path)
+        end
+      elsif before.is_a?(Array)
+        if !after.is_a?(Array)
+          changes << JsonDiff.replace(path, include_was(path) ? before : nil, after) if include_replace(path)
+        else
+          diff_array(before, after, path)
+        end
+      else
+        if before != after
+          changes << JsonDiff.replace(path, include_was(path) ? before : nil, after) if include_replace(path)
+        end
+      end
+    end
+
+    def include_addition(type, path)
+      return true if opts[:additions] == nil
+      opts[:additions].respond_to?(:call) ? opts[:additions].call(type, path) : opts[:additions]
+    end
+
+    def include_moves(path)
+      return true if opts[:moves] == nil
+      opts[:moves].respond_to?(:call) ? opts[:moves].call(path) : opts[:moves]
+    end
+
+    def include_replace(path)
+      return true if opts[:replace] == nil
+      opts[:replace].respond_to?(:call) ? opts[:replace].call(path) : opts[:replace]
+    end
+
+    def include_was(path)
+      return false if opts[:include_was] == nil
+      opts[:include_was].respond_to?(:call) ? opts[:include_was].call(path) : opts[:include_was]
+    end
+
+    def original_indices(path)
+      return false if opts[:original_indices] == nil
+      opts[:original_indices].respond_to?(:call) ? opts[:original_indices].call(path) : opts[:original_indices]
+    end
+  end
+end
+
diff --git a/lib/json-diff/version.rb b/lib/json-diff/version.rb
index 10e755e..541b44a 100644
--- a/lib/json-diff/version.rb
+++ b/lib/json-diff/version.rb
@@ -1,3 +1,3 @@
 module JsonDiff
-  VERSION = '0.4.1'
+  VERSION = '0.5.0-dwhenry'
 end
diff --git a/spec/json-diff/diff_spec.rb b/spec/json-diff/diff_spec.rb
index 28ea6f6..f322f77 100644
--- a/spec/json-diff/diff_spec.rb
+++ b/spec/json-diff/diff_spec.rb
@@ -4,12 +4,12 @@
   # Arrays
 
   it "should be able to diff two empty arrays" do
-    diff = JsonDiff.diff([], [])
+    diff = described_class.diff([], [])
     expect(diff).to eql([])
   end
 
   it "should be able to diff an empty array with a filled one" do
-    diff = JsonDiff.diff([], [1, 2, 3], include_was: true)
+    diff = described_class.diff([], [1, 2, 3], include_was: true)
     expect(diff).to eql([
       {'op' => 'add', 'path' => "/0", 'value' => 1},
       {'op' => 'add', 'path' => "/1", 'value' => 2},
@@ -18,7 +18,7 @@
   end
 
   it "should be able to diff a filled array with an empty one" do
-    diff = JsonDiff.diff([1, 2, 3], [], include_was: true)
+    diff = described_class.diff([1, 2, 3], [], include_was: true)
     expect(diff).to eql([
       {'op' => 'remove', 'path' => "/0", 'was' => 1},
       {'op' => 'remove', 'path' => "/0", 'was' => 2},
@@ -27,7 +27,7 @@
   end
 
   it "should be able to diff a 1-array with a filled one" do
-    diff = JsonDiff.diff([0], [1, 2, 3], include_was: true)
+    diff = described_class.diff([0], [1, 2, 3], include_was: true)
     expect(diff).to eql([
       {'op' => 'remove', 'path' => "/0", 'was' => 0},
       {'op' => 'add', 'path' => "/0", 'value' => 1},
@@ -37,7 +37,7 @@
   end
 
   it "should be able to diff a filled array with a 1-array" do
-    diff = JsonDiff.diff([1, 2, 3], [0], include_was: true)
+    diff = described_class.diff([1, 2, 3], [0], include_was: true)
     expect(diff).to eql([
       {'op' => 'remove', 'path' => "/2", 'was' => 3},
       {'op' => 'remove', 'path' => "/1", 'was' => 2},
@@ -47,7 +47,7 @@
   end
 
   it "should be able to diff two integer arrays" do
-    diff = JsonDiff.diff([1, 2, 3, 4, 5], [6, 4, 3, 2], include_was: true)
+    diff = described_class.diff([1, 2, 3, 4, 5], [6, 4, 3, 2], include_was: true)
     expect(diff).to eql([
       {'op' => 'remove', 'path' => "/4", 'was' => 5},
       {'op' => 'remove', 'path' => "/0", 'was' => 1},
@@ -58,12 +58,12 @@
   end
 
   it "should be able to diff a ring switch" do
-    diff = JsonDiff.diff([1, 2, 3], [2, 3, 1], include_was: true)
+    diff = described_class.diff([1, 2, 3], [2, 3, 1], include_was: true)
     expect(diff).to eql([{"op" => "move", "from" => "/0", "path" => "/2"}])
   end
 
   it "should be able to diff a ring switch with removals and additions" do
-    diff = JsonDiff.diff([1, 2, 3, 4], [5, 3, 4, 2], include_was: true)
+    diff = described_class.diff([1, 2, 3, 4], [5, 3, 4, 2], include_was: true)
     expect(diff).to eql([
       {"op" => "remove", "path" => "/0", "was" => 1},
       {"op" => "move", "from" => "/0", "path" => "/2"},
@@ -72,7 +72,7 @@
   end
 
   it "should be able to diff an array with many additions at its start" do
-    diff = JsonDiff.diff([0], [1, 2, 3, 0])
+    diff = described_class.diff([0], [1, 2, 3, 0])
     expect(diff).to eql([
       {'op' => 'add', 'path' => "/0", 'value' => 1},
       {'op' => 'add', 'path' => "/1", 'value' => 2},
@@ -81,7 +81,7 @@
   end
 
   it "should be able to diff two arrays with mixed content" do
-    diff = JsonDiff.diff(["laundry", 12, {'pillar' => 0}, true], [true, {'pillar' => 1}, 3, 12], include_was: true)
+    diff = described_class.diff(["laundry", 12, {'pillar' => 0}, true], [true, {'pillar' => 1}, 3, 12], include_was: true)
     expect(diff).to eql([
       {'op' => 'replace', 'path' => "/2/pillar", 'was' => 0, 'value' => 1},
       {'op' => 'remove', 'path' => "/0", 'was' => "laundry"},
@@ -94,7 +94,7 @@
   # Objects
 
   it "should be able to diff two objects with mixed content" do
-    diff = JsonDiff.diff(
+    diff = described_class.diff(
       {'string' => "laundry", 'number' => 12, 'object' => {'pillar' => 0}, 'list' => [2, 4, 1], 'bool' => false, 'null' => nil},
       {'string' => "laundry", 'number' => 12, 'object' => {'pillar' => 1}, 'list' => [1, 2, 3], 'bool' => true, 'null' => nil},
       include_was: true)
@@ -110,7 +110,7 @@
   # Trans-type
 
   it "should be able to diff two objects of mixed type" do
-    diff = JsonDiff.diff(0, "0", include_was: true)
+    diff = described_class.diff(0, "0", include_was: true)
     expect(diff).to eql([
       {'op' => 'replace', 'path' => '', 'was' => 0, 'value' => "0"}
     ])
@@ -119,7 +119,7 @@
   # Options
 
   it "should be able to diff two integer arrays with original indices" do
-    diff = JsonDiff.diff([1, 2, 3, 4, 5], [6, 4, 3, 2], original_indices: true)
+    diff = described_class.diff([1, 2, 3, 4, 5], [6, 4, 3, 2], original_indices: true)
     expect(diff).to eql([
       {'op' => 'remove', 'path' => "/4"},
       {'op' => 'remove', 'path' => "/0"},
@@ -130,7 +130,7 @@
   end
 
   it "should be able to diff two integer arrays without move operations" do
-    diff = JsonDiff.diff([1, 2, 3, 4, 5], [6, 4, 3, 2], moves: false)
+    diff = described_class.diff([1, 2, 3, 4, 5], [6, 4, 3, 2], moves: false)
     expect(diff).to eql([
       {'op' => 'remove', 'path' => "/4"},
       {'op' => 'remove', 'path' => "/0"},
@@ -139,7 +139,7 @@
   end
 
   it "should be able to diff two integer arrays without add operations" do
-    diff = JsonDiff.diff([1, 2, 3, 4, 5], [6, 4, 3, 2], additions: false)
+    diff = described_class.diff([1, 2, 3, 4, 5], [6, 4, 3, 2], additions: false)
     expect(diff).to eql([
       {'op' => 'remove', 'path' => "/4"},
       {'op' => 'remove', 'path' => "/0"},
@@ -159,7 +159,7 @@
       end
     end
 
-    diff = JsonDiff.diff([
+    diff = described_class.diff([
       {id: 1, we: "must", start: "somewhere"},
       {id: 2, and: "this", will: "do"},
     ], [
diff --git a/spec/json-diff/v2/diff_spec.rb b/spec/json-diff/v2/diff_spec.rb
new file mode 100644
index 0000000..6c0440f
--- /dev/null
+++ b/spec/json-diff/v2/diff_spec.rb
@@ -0,0 +1,182 @@
+require 'spec_helper'
+
+describe JsonDiff::V2 do
+  # Arrays
+
+  it "should be able to diff two empty arrays" do
+    diff = described_class.diff([], [])
+    expect(diff).to eql([])
+  end
+
+  it "should be able to diff an empty array with a filled one" do
+    diff = described_class.diff([], [1, 2, 3], include_was: true)
+    expect(diff).to eql([
+      {'op' => 'add', 'path' => "/0", 'value' => 1},
+      {'op' => 'add', 'path' => "/1", 'value' => 2},
+      {'op' => 'add', 'path' => "/2", 'value' => 3},
+    ])
+  end
+
+  it "should be able to diff a filled array with an empty one" do
+    diff = described_class.diff([1, 2, 3], [], include_was: true)
+    expect(diff).to eql([
+      {'op' => 'remove', 'path' => "/0", 'was' => 1},
+      {'op' => 'remove', 'path' => "/0", 'was' => 2},
+      {'op' => 'remove', 'path' => "/0", 'was' => 3},
+    ])
+  end
+
+  it "should be able to diff a 1-array with a filled one" do
+    diff = described_class.diff([0], [1, 2, 3], include_was: true)
+    expect(diff).to eql([
+      {'op' => 'remove', 'path' => "/0", 'was' => 0},
+      {'op' => 'add', 'path' => "/0", 'value' => 1},
+      {'op' => 'add', 'path' => "/1", 'value' => 2},
+      {'op' => 'add', 'path' => "/2", 'value' => 3},
+    ])
+  end
+
+  it "should be able to diff a filled array with a 1-array" do
+    diff = described_class.diff([1, 2, 3], [0], include_was: true)
+    expect(diff).to eql([
+      {'op' => 'remove', 'path' => "/2", 'was' => 3},
+      {'op' => 'remove', 'path' => "/1", 'was' => 2},
+      {'op' => 'remove', 'path' => "/0", 'was' => 1},
+      {'op' => 'add', 'path' => "/0", 'value' => 0},
+    ])
+  end
+
+  it "should be able to diff two integer arrays" do
+    diff = described_class.diff([1, 2, 3, 4, 5], [6, 4, 3, 2], include_was: true)
+    expect(diff).to eql([
+      {'op' => 'remove', 'path' => "/4", 'was' => 5},
+      {'op' => 'remove', 'path' => "/0", 'was' => 1},
+      {'op' => 'move', 'from' => "/0", 'path' => "/2"},
+      {'op' => 'move', 'from' => "/1", 'path' => "/0"},
+      {'op' => 'add', 'path' => "/0", 'value' => 6},
+    ])
+  end
+
+  it "should be able to diff a ring switch" do
+    diff = described_class.diff([1, 2, 3], [2, 3, 1], include_was: true)
+    expect(diff).to eql([{"op" => "move", "from" => "/0", "path" => "/2"}])
+  end
+
+  it "should be able to diff a ring switch with removals and additions" do
+    diff = described_class.diff([1, 2, 3, 4], [5, 3, 4, 2], include_was: true)
+    expect(diff).to eql([
+      {"op" => "remove", "path" => "/0", "was" => 1},
+      {"op" => "move", "from" => "/0", "path" => "/2"},
+      {"op" => "add", "path" => "/0", "value" => 5},
+    ])
+  end
+
+  it "should be able to diff an array with many additions at its start" do
+    diff = described_class.diff([0], [1, 2, 3, 0])
+    expect(diff).to eql([
+      {'op' => 'add', 'path' => "/0", 'value' => 1},
+      {'op' => 'add', 'path' => "/1", 'value' => 2},
+      {'op' => 'add', 'path' => "/2", 'value' => 3},
+    ])
+  end
+
+  it "should be able to diff two arrays with mixed content" do
+    diff = described_class.diff(["laundry", 12, {'pillar' => 0}, true], [true, {'pillar' => 1}, 3, 12], include_was: true)
+    expect(diff).to eql([
+      {'op' => 'replace', 'path' => "/2/pillar", 'was' => 0, 'value' => 1},
+      {'op' => 'remove', 'path' => "/0", 'was' => "laundry"},
+      {'op' => 'move', 'from' => "/0", 'path' => "/2"},
+      {'op' => 'move', 'from' => "/1", 'path' => "/0"},
+      {'op' => 'add', 'path' => "/2", 'value' => 3},
+    ])
+  end
+
+  # Objects
+
+  it "should be able to diff two objects with mixed content" do
+    diff = described_class.diff(
+      {'string' => "laundry", 'number' => 12, 'object' => {'pillar' => 0}, 'list' => [2, 4, 1], 'bool' => false, 'null' => nil},
+      {'string' => "laundry", 'number' => 12, 'object' => {'pillar' => 1}, 'list' => [1, 2, 3], 'bool' => true, 'null' => nil},
+      include_was: true)
+    expect(diff).to eql([
+      {'op' => 'replace', 'path' => "/object/pillar", 'was' => 0, 'value' => 1},
+      {'op' => 'remove', 'path' => "/list/1", 'was' => 4},
+      {'op' => 'move', 'from' => "/list/0", 'path' => "/list/1"},
+      {'op' => 'add', 'path' => "/list/2", 'value' => 3},
+      {'op' => 'replace', 'path' => "/bool", 'was' => false, 'value' => true},
+    ])
+  end
+
+  # Trans-type
+
+  it "should be able to diff two objects of mixed type" do
+    diff = described_class.diff(0, "0", include_was: true)
+    expect(diff).to eql([
+      {'op' => 'replace', 'path' => '', 'was' => 0, 'value' => "0"}
+    ])
+  end
+
+  # Options
+
+  it "should be able to diff two integer arrays with original indices" do
+    diff = described_class.diff([1, 2, 3, 4, 5], [6, 4, 3, 2], original_indices: true)
+    expect(diff).to eql([
+      {'op' => 'remove', 'path' => "/4"},
+      {'op' => 'remove', 'path' => "/0"},
+      {'op' => 'move', 'from' => "/1", 'path' => "/3"},
+      {'op' => 'move', 'from' => "/3", 'path' => "/1"},
+      {'op' => 'add', 'path' => "/0", 'value' => 6},
+    ])
+  end
+
+  it "should be able to diff two integer arrays without move operations" do
+    diff = described_class.diff([1, 2, 3, 4, 5], [6, 4, 3, 2], moves: false)
+    expect(diff).to eql([
+      {'op' => 'remove', 'path' => "/4"},
+      {'op' => 'remove', 'path' => "/0"},
+      {'op' => 'add', 'path' => "/0", 'value' => 6},
+    ])
+  end
+
+  it "should be able to diff two integer arrays without add operations" do
+    diff = described_class.diff([1, 2, 3, 4, 5], [6, 4, 3, 2], additions: false)
+    expect(diff).to eql([
+      {'op' => 'remove', 'path' => "/4"},
+      {'op' => 'remove', 'path' => "/0"},
+      {'op' => 'move', 'from' => "/0", 'path' => "/2"},
+      {'op' => 'move', 'from' => "/1", 'path' => "/0"},
+    ])
+  end
+
+  it "should be able to diff two objects with a custom similarity" do
+    similarity = -> (before, after) do
+      if before.is_a?(Hash) && after.is_a?(Hash)
+        if before[:id] == after[:id]
+          1.0
+        else
+          0.0
+        end
+      end
+    end
+
+    diff = described_class.diff([
+      {id: 1, we: "must", start: "somewhere"},
+      {id: 2, and: "this", will: "do"},
+    ], [
+      {id: 2, insert: "something", completely: "different"},
+      {id: 1, this: "too", is: "different"},
+    ], similarity: similarity)
+    expect(diff).to eql([
+      {'op' => 'remove', 'path' => '/0/we'},
+      {'op' => 'remove', 'path' => '/0/start'},
+      {'op' => 'add', 'path' => '/0/this', 'value' => 'too'},
+      {'op' => 'add', 'path' => '/0/is', 'value' => 'different'},
+      {'op' => 'remove', 'path' => '/1/and'},
+      {'op' => 'remove', 'path' => '/1/will'},
+      {'op' => 'add', 'path' => '/1/insert', 'value' => 'something'},
+      {'op' => 'add', 'path' => '/1/completely', 'value' => 'different'},
+      {'op' => 'move', 'from' => '/0', 'path' => '/1'},
+    ])
+  end
+
+end