diff --git a/WakaTime/Helpers/Dependencies.swift b/WakaTime/Helpers/Dependencies.swift
index 6510a62..51e3f71 100644
--- a/WakaTime/Helpers/Dependencies.swift
+++ b/WakaTime/Helpers/Dependencies.swift
@@ -15,6 +15,62 @@ class Dependencies {
         Bundle.main.version == "local-build"
     }
 
+    public static func recentBrowserExtension() async -> String? {
+        guard
+            let apiKey = ConfigFile.getSetting(section: "settings", key: "api_key"),
+            !apiKey.isEmpty
+        else { return nil }
+        let url = "https://api.wakatime.com/api/v1/users/current/user_agents?api_key=\(apiKey)"
+        let request = URLRequest(url: URL(string: url)!, cachePolicy: .reloadIgnoringCacheData)
+        do {
+            let (data, response) = try await URLSession.shared.data(for: request)
+            guard
+                let httpResponse = response as? HTTPURLResponse,
+                httpResponse.statusCode == 200
+            else { return nil }
+
+            struct Resp: Decodable {
+                let data: [UserAgent]
+            }
+            struct UserAgent: Decodable {
+                let isBrowserExtension: Bool
+                let editor: String?
+                let lastSeenAt: String?
+                enum CodingKeys: String, CodingKey {
+                    case isBrowserExtension = "is_browser_extension"
+                    case editor
+                    case lastSeenAt = "last_seen_at"
+                }
+            }
+
+            let release = try JSONDecoder().decode(Resp.self, from: data)
+            let now = Date()
+            for agent in release.data {
+                guard
+                    agent.isBrowserExtension,
+                    let editor = agent.editor,
+                    !editor.isEmpty,
+                    let lastSeenAt = agent.lastSeenAt
+                else { continue }
+
+                let isoDateFormatter = ISO8601DateFormatter()
+                isoDateFormatter.timeZone = TimeZone(secondsFromGMT: 0)
+                isoDateFormatter.formatOptions = [.withInternetDateTime]
+                if let lastSeen = isoDateFormatter.date(from: lastSeenAt) {
+                    if now.timeIntervalSince(lastSeen) > 600 {
+                        break
+                    }
+                }
+
+                return agent.editor
+            }
+        } catch {
+            Logging.default.log("Request error checking for conflicting browser extension: \(error)")
+            return nil
+        }
+        return nil
+    }
+
     private static func getLatestVersion() async throws -> String? {
         struct Release: Decodable {
             let tagName: String
diff --git a/WakaTime/WakaTime.swift b/WakaTime/WakaTime.swift
index dced6c2..1dc0c78 100644
--- a/WakaTime/WakaTime.swift
+++ b/WakaTime/WakaTime.swift
@@ -50,6 +50,16 @@ class WakaTime: HeartbeatEventHandler {
             }
             PropertiesManager.hasLaunchedBefore = true
         }
+
+        if MonitoringManager.isMonitoringBrowsing {
+            Task {
+                if let browser = await Dependencies.recentBrowserExtension() {
+                    delegate.toastNotification("Warning: WakaTime \(browser) extension detected. " +
+                        "It’s recommended to only track browsing activity with the \(browser) " +
+                        "extension or Mac Desktop app, but not both.")
+                }
+            }
+        }
     }
 
     private func configureFirebase() {