diff --git a/DevToys.xcworkspace/xcshareddata/swiftpm/Package.resolved b/DevToys.xcworkspace/xcshareddata/swiftpm/Package.resolved
index b40a58d..2b97697 100644
--- a/DevToys.xcworkspace/xcshareddata/swiftpm/Package.resolved
+++ b/DevToys.xcworkspace/xcshareddata/swiftpm/Package.resolved
@@ -15,8 +15,8 @@
         "repositoryURL": "https://github.com/ObuchiYuki/DiffMatchPatch",
         "state": {
           "branch": null,
-          "revision": "7f79f4a473e0e81d6864b425f101c78bccfd169b",
-          "version": "1.0.0"
+          "revision": "5db22e8f9ac588a130f62733105bbe5c5bdd7bc3",
+          "version": "1.0.3"
         }
       },
       {
diff --git a/DevToys/DevToys/Body/Text/TextDiffView+.swift b/DevToys/DevToys/Body/Text/TextDiffView+.swift
index 1e93043..4b8eed0 100644
--- a/DevToys/DevToys/Body/Text/TextDiffView+.swift
+++ b/DevToys/DevToys/Body/Text/TextDiffView+.swift
@@ -5,4 +5,112 @@
 //  Created by yuki on 2022/02/23.
 //
 
-import Foundation
+import DiffMatchPatch
+import CoreUtil
+
+final class TextDiffViewController: NSViewController {
+    
+    @RestorableState("textdiff.operation") var operation: TextCheckOperation = .characters
+    @RestorableState("textdiff.input1") var input1 = ""
+    @RestorableState("textdiff.input2") var input2 = ""
+    
+    @Observable var diffAttributedString = NSAttributedString()
+    
+    private let cell = TextDiffView()
+
+    override func loadView() { self.view = cell }
+    
+    override func viewDidLoad() {
+        self.$operation
+            .sink{[unowned self] in self.cell.checkOperationPicker.selectedItem = $0 }.store(in: &objectBag)
+        self.$input1
+            .sink{[unowned self] in self.cell.input1Section.string = $0 }.store(in: &objectBag)
+        self.$input2
+            .sink{[unowned self] in self.cell.input2Section.string = $0 }.store(in: &objectBag)
+        self.$diffAttributedString
+            .sink{[unowned self] in self.cell.outputSection.textView.textView.textStorage?.setAttributedString($0) }.store(in: &objectBag)
+        
+        self.cell.input1Section.stringPublisher
+            .sink{[unowned self] in self.input1 = $0; updateDiff() }.store(in: &objectBag)
+        self.cell.input2Section.stringPublisher
+            .sink{[unowned self] in self.input2 = $0; updateDiff() }.store(in: &objectBag)
+        self.cell.checkOperationPicker.itemPublisher
+            .sink{[unowned self] in self.operation = $0; updateDiff() }.store(in: &objectBag)
+        
+        self.updateDiff()
+    }
+    
+    private func updateDiff() {
+        let diffs = TextDifferenceChecker.compare(input1, input2, operation: self.operation)
+        self.diffAttributedString = buildAttributedString(from: diffs)
+    }
+    
+    private func buildAttributedString(from diffs: [Difference]) -> NSAttributedString {
+        let attributedString = NSMutableAttributedString()
+        let defaultAttributes = [
+            NSAttributedString.Key.foregroundColor: NSColor.textColor,
+            NSAttributedString.Key.font : NSFont.monospacedSystemFont(ofSize: 12, weight: .regular)
+        ]
+        
+        for diff in diffs {
+            switch diff.operation {
+            case .equal:
+                attributedString.append(NSAttributedString(string: diff.text, attributes: defaultAttributes))
+            case .insert:
+                attributedString.append(NSAttributedString(string: diff.text, attributes: defaultAttributes.merging([
+                    NSAttributedString.Key.backgroundColor : NSColor.systemGreen.withAlphaComponent(0.7)
+                ], uniquingKeysWith: { a, _ in a }) ))
+            case .delete:
+                attributedString.append(NSAttributedString(string: diff.text, attributes: defaultAttributes.merging([
+                    NSAttributedString.Key.backgroundColor : NSColor.systemRed.withAlphaComponent(0.7)
+                ], uniquingKeysWith: { a, _ in a }) ))
+            }
+        }
+        
+        return attributedString
+    }
+}
+
+extension TextCheckOperation: TextItem {
+    public static let allCases: [TextCheckOperation] = [.characters, .words, .lines]
+    
+    var title: String {
+        switch self {
+        case .characters: return "Characters"
+        case .words: return "Words"
+        case .lines: return "Lines"
+        }
+    }
+}
+
+final private class TextDiffView: Page {
+    let checkOperationPicker = EnumPopupButton<TextCheckOperation>()
+    
+    let input1Section = CodeViewSection(title: "Input 1".localized(), options: .defaultInput, language: .plaintext)
+    let input2Section = CodeViewSection(title: "Input 2".localized(), options: .defaultInput, language: .plaintext)
+    let outputSection = TextViewSection(title: "Output".localized(), options: .defaultOutput)
+
+    override func layout() {
+        super.layout()
+        
+    }
+    
+    override func onAwake() {
+        self.addSection(Section(title: "Configuration".localized(), items: [
+            Area(icon: R.Image.format, title: "Diff Style", control: checkOperationPicker)
+        ]))
+        
+        self.addSection2(input1Section, input2Section)
+        self.input1Section.snp.makeConstraints{ make in
+            make.height.equalTo(320)
+        }
+        
+        self.addSection(outputSection)
+        self.outputSection.textView.textView.font = .monospacedSystemFont(ofSize: 12, weight: .regular)
+        self.outputSection.snp.makeConstraints{ make in
+            make.height.equalTo(320)
+        }
+        
+    }
+}
+
diff --git a/DevToys/DevToys/Component/TextView.swift b/DevToys/DevToys/Component/TextView.swift
index 34bdc38..f353745 100644
--- a/DevToys/DevToys/Component/TextView.swift
+++ b/DevToys/DevToys/Component/TextView.swift
@@ -8,7 +8,7 @@
 import CoreUtil
 
 final class TextView: NSLoadView {
-    private class _TextView: NSTextView {
+    class _TextView: NSTextView {
         let stringPublisher = PassthroughSubject<String, Never>()
         var sendingValue = false
         override var string: String {
@@ -38,7 +38,7 @@ final class TextView: NSLoadView {
     
     private let scrollView = _TextView.scrollableTextView()
     private let backgroudLayer = ControlBackgroundLayer.animationDisabled()
-    private lazy var textView = scrollView.documentView as! _TextView
+    lazy var textView = scrollView.documentView as! _TextView
 
     override func onAwake() {
         self.wantsLayer = true
diff --git a/DevToys/DevToys/Model/Tool+Default.swift b/DevToys/DevToys/Model/Tool+Default.swift
index 193cf9e..d5e7bfe 100644
--- a/DevToys/DevToys/Model/Tool+Default.swift
+++ b/DevToys/DevToys/Model/Tool+Default.swift
@@ -108,12 +108,18 @@ extension Tool {
         sidebarTitle: "tool.regex.mintitle".localized(), toolDescription: "tool.regex.description".localized(),
         viewController: RegexTesterViewController()
     )
+    static let textDiff = Tool(
+        title: "Text Diff".localized(), identifier: "textdiff", category: .text, icon: R.Image.Tool.textInspector,
+        sidebarTitle: "Text Diff".localized(), toolDescription: "Compare two Text and display Diff".localized(),
+        viewController: TextDiffViewController()
+    )
     static let hyphenationRemover = Tool(
         title: "tool.hyphenremove.title".localized(), identifier: "hyphenremove", category: .text, icon: R.Image.Tool.textInspector,
         sidebarTitle: "tool.hyphenremove.mintitle".localized(), toolDescription: "tool.hyphenremove.description".localized(),
         viewController: HyphenationRemoverViewController()
     )
     
+    
     // MARK: - Graphic -
     static let imageOptimizer = Tool(
         title: "tool.imageoptim.title".localized(), identifier: "imageoptim", category: .graphic, icon: R.Image.Tool.imageCompressor,
@@ -172,6 +178,7 @@ extension ToolManager {
 
         toolManager.registerTool(.textInspector)
         toolManager.registerTool(.regexTester)
+        toolManager.registerTool(.textDiff)
         toolManager.registerTool(.hyphenationRemover)
 
         toolManager.registerTool(.imageOptimizer)