diff --git a/Sources/RDEpubReaderView/EPUBUI/RDEPUBReaderTopToolView.swift b/Sources/RDEpubReaderView/EPUBUI/RDEPUBReaderTopToolView.swift
index 28ddb84..0ca47f6 100644
--- a/Sources/RDEpubReaderView/EPUBUI/RDEPUBReaderTopToolView.swift
+++ b/Sources/RDEpubReaderView/EPUBUI/RDEPUBReaderTopToolView.swift
@@ -1,6 +1,6 @@
 import UIKit
 
-public final class RDEPUBReaderTopToolView: RDEPUBReaderToolView, RDEPUBReaderTopToolViewProtocol {
+open class RDEPUBReaderTopToolView: RDEPUBReaderToolView, RDEPUBReaderTopToolViewProtocol {
 
     public var onBack: (() -> Void)?
 
@@ -8,9 +8,14 @@ public final class RDEPUBReaderTopToolView: RDEPUBReaderToolView, RDEPUBReaderTo
 
     public var onSearch: (() -> Void)?
 
+    /// 宿主可配置的登录 / 购买等业务入口。未设置标题时不占用工具栏空间。
+    public var onAuthorization: (() -> Void)?
+
     private let backButton = RDEPUBReaderTintButton(type: .system)
     private let searchButton = RDEPUBReaderTintButton(type: .system)
     private let bookmarkButton = RDEPUBReaderTintButton(type: .system)
+    private let authorizationButton = RDEPUBReaderTintButton(type: .system)
+    private var authorizationButtonWidthConstraint: NSLayoutConstraint!
     private let titleLabel: UILabel = {
         let label = UILabel()
         label.textAlignment = .center
@@ -20,23 +25,28 @@ public final class RDEPUBReaderTopToolView: RDEPUBReaderToolView, RDEPUBReaderTo
     }()
     private var isBookmarked = false
 
-    override init(frame: CGRect) {
+    public override init(frame: CGRect) {
         super.init(frame: frame)
         accessibilityIdentifier = "epub.reader.topToolbar"
         self.backgroundColor = .white
         addSubview(backButton)
         addSubview(searchButton)
         addSubview(bookmarkButton)
+        addSubview(authorizationButton)
         addSubview(titleLabel)
 
         backButton.translatesAutoresizingMaskIntoConstraints = false
         searchButton.translatesAutoresizingMaskIntoConstraints = false
         bookmarkButton.translatesAutoresizingMaskIntoConstraints = false
+        authorizationButton.translatesAutoresizingMaskIntoConstraints = false
         titleLabel.translatesAutoresizingMaskIntoConstraints = false
 
         backButton.addTarget(self, action: #selector(backAction), for: .touchUpInside)
         searchButton.addTarget(self, action: #selector(searchAction), for: .touchUpInside)
         bookmarkButton.addTarget(self, action: #selector(bookmarkAction), for: .touchUpInside)
+        authorizationButton.addTarget(self, action: #selector(authorizationAction), for: .touchUpInside)
+
+        authorizationButtonWidthConstraint = authorizationButton.widthAnchor.constraint(equalToConstant: 0)
 
         NSLayoutConstraint.activate([
             backButton.leadingAnchor.constraint(equalTo: leadingAnchor, constant: 8),
@@ -45,7 +55,13 @@ public final class RDEPUBReaderTopToolView: RDEPUBReaderToolView, RDEPUBReaderTo
             backButton.widthAnchor.constraint(equalToConstant: 44),
             backButton.heightAnchor.constraint(equalToConstant: 44),
 
-            bookmarkButton.trailingAnchor.constraint(equalTo: trailingAnchor, constant: -8),
+            authorizationButton.trailingAnchor.constraint(equalTo: trailingAnchor, constant: -8),
+            authorizationButton.topAnchor.constraint(equalTo: safeAreaLayoutGuide.topAnchor, constant: 4),
+            authorizationButton.bottomAnchor.constraint(equalTo: bottomAnchor, constant: -4),
+            authorizationButton.heightAnchor.constraint(equalToConstant: 44),
+            authorizationButtonWidthConstraint,
+
+            bookmarkButton.trailingAnchor.constraint(equalTo: authorizationButton.leadingAnchor, constant: -4),
             bookmarkButton.topAnchor.constraint(equalTo: safeAreaLayoutGuide.topAnchor, constant: 4),
             bookmarkButton.bottomAnchor.constraint(equalTo: bottomAnchor, constant: -4),
             bookmarkButton.widthAnchor.constraint(equalToConstant: 44),
@@ -72,11 +88,12 @@ public final class RDEPUBReaderTopToolView: RDEPUBReaderToolView, RDEPUBReaderTo
         backButton.accessibilityIdentifier = "epub.reader.back"
         searchButton.accessibilityIdentifier = "epub.reader.search"
         bookmarkButton.accessibilityIdentifier = "epub.reader.bookmark"
+        authorizationButton.accessibilityIdentifier = "epub.reader.authorization"
         titleLabel.accessibilityIdentifier = "epub.reader.title"
         updateBookmarkButtonAppearance()
     }
 
-    required init?(coder: NSCoder) {
+    public required init?(coder: NSCoder) {
         fatalError("init(coder:) has not been implemented")
     }
 
@@ -90,10 +107,12 @@ public final class RDEPUBReaderTopToolView: RDEPUBReaderToolView, RDEPUBReaderTo
         backButton.tintColor = theme.toolControlTextColor
         searchButton.tintColor = theme.toolControlTextColor
         bookmarkButton.tintColor = theme.toolControlTextColor
+        authorizationButton.tintColor = theme.toolControlTextColor
         if #unavailable(iOS 13.0) {
             backButton.setTitleColor(theme.toolControlTextColor, for: .normal)
             searchButton.setTitleColor(theme.toolControlTextColor, for: .normal)
             bookmarkButton.setTitleColor(theme.toolControlTextColor, for: .normal)
+            authorizationButton.setTitleColor(theme.toolControlTextColor, for: .normal)
         }
         updateBookmarkButtonAppearance()
     }
@@ -112,6 +131,17 @@ public final class RDEPUBReaderTopToolView: RDEPUBReaderToolView, RDEPUBReaderTo
         bookmarkButton.alpha = isEnabled ? 1 : 0.45
     }
 
+    /// 设置右上角业务按钮。传 `nil` 或空字符串时隐藏按钮并恢复原工具栏布局。
+    public func setAuthorizationButton(title: String?) {
+        let resolvedTitle = title?.trimmingCharacters(in: .whitespacesAndNewlines)
+        let isVisible = resolvedTitle?.isEmpty == false
+        authorizationButton.setTitle(resolvedTitle, for: .normal)
+        authorizationButton.isHidden = !isVisible
+        authorizationButton.isEnabled = isVisible
+        authorizationButtonWidthConstraint.constant = isVisible ? 56 : 0
+        authorizationButton.accessibilityLabel = resolvedTitle
+    }
+
     @objc private func backAction() {
         onBack?()
     }
@@ -124,6 +154,10 @@ public final class RDEPUBReaderTopToolView: RDEPUBReaderToolView, RDEPUBReaderTo
         onToggleBookmark?()
     }
 
+    @objc private func authorizationAction() {
+        onAuthorization?()
+    }
+
     private func updateBookmarkButtonAppearance() {
         if #available(iOS 13.0, *) {
             let imageName = isBookmarked ? "bookmark.fill" : "bookmark"