diff --git a/.dockerignore b/.dockerignore
index f626ebaa..797912e7 100644
--- a/.dockerignore
+++ b/.dockerignore
@@ -38,4 +38,5 @@ log.csv
 vendor
 
 workdir
-Dockerfile
\ No newline at end of file
+Dockerfile
+macos/
diff --git a/macos/.gitignore b/macos/.gitignore
new file mode 100644
index 00000000..30bcfa4e
--- /dev/null
+++ b/macos/.gitignore
@@ -0,0 +1 @@
+.build/
diff --git a/macos/Package.resolved b/macos/Package.resolved
new file mode 100644
index 00000000..556ef1ac
--- /dev/null
+++ b/macos/Package.resolved
@@ -0,0 +1,14 @@
+{
+  "pins" : [
+    {
+      "identity" : "yams",
+      "kind" : "remoteSourceControl",
+      "location" : "https://github.com/jpsim/Yams.git",
+      "state" : {
+        "revision" : "a27b21e0c81c5bf42049b897a62aaf387e80f279",
+        "version" : "6.2.2"
+      }
+    }
+  ],
+  "version" : 2
+}
diff --git a/macos/Package.swift b/macos/Package.swift
new file mode 100644
index 00000000..24028aa0
--- /dev/null
+++ b/macos/Package.swift
@@ -0,0 +1,12 @@
+// swift-tools-version:5.9
+import PackageDescription
+
+let package = Package(
+    name: "Nylon",
+    platforms: [.macOS(.v14)],
+    dependencies: [.package(url: "https://github.com/jpsim/Yams.git", from: "6.2.2")],
+    targets: [
+        .executableTarget(name: "NylonApp", dependencies: ["Yams"]),
+        .testTarget(name: "NylonAppTests", dependencies: ["NylonApp"]),
+    ]
+)
diff --git a/macos/README.md b/macos/README.md
new file mode 100644
index 00000000..da49a34c
--- /dev/null
+++ b/macos/README.md
@@ -0,0 +1,24 @@
+# Nylon for macOS
+
+A menu bar app that lists the nodes in your nylon network with their IPs. Click a node to copy its IP.
+
+## Run it
+
+1. Install the Command Line Tools if you don't have them: `xcode-select --install`
+2. From the repo root, build and start it:
+
+   ```bash
+   swift build -c release --package-path macos && macos/.build/release/NylonApp
+   ```
+
+3. Click the network icon in the menu bar, then "Choose central.yaml…" and pick your file. The app remembers it for next time.
+
+To skip the picker, pass the file: `macos/.build/release/NylonApp -central /path/to/central.yaml`. With no file chosen, it reads `central.yaml` in the current directory, like `nylon run`.
+
+## Test
+
+```bash
+swift test --package-path macos -Xswiftc -plugin-path -Xswiftc "$(xcode-select -p)/usr/lib/swift/host/plugins/testing"
+```
+
+The `-plugin-path` flag is only needed without full Xcode.
diff --git a/macos/Sources/NylonApp/Central.swift b/macos/Sources/NylonApp/Central.swift
new file mode 100644
index 00000000..74b5d45b
--- /dev/null
+++ b/macos/Sources/NylonApp/Central.swift
@@ -0,0 +1,22 @@
+import Foundation
+import Yams
+
+struct Node: Equatable {
+    let name: String
+    let address: String? // first mesh IP; nil for a node that only advertises prefixes
+}
+
+// central.yaml, just the parts shown here. Every router and client is a node.
+private struct Central: Decodable {
+    struct Entry: Decodable {
+        let id: String
+        let addresses: [String]?
+    }
+    let routers: [Entry]?
+    let clients: [Entry]?
+}
+
+func readNodes(_ yaml: String) throws -> [Node] {
+    let c = try YAMLDecoder().decode(Central.self, from: yaml)
+    return ((c.routers ?? []) + (c.clients ?? [])).map { Node(name: $0.id, address: $0.addresses?.first) }
+}
diff --git a/macos/Sources/NylonApp/MenuContent.swift b/macos/Sources/NylonApp/MenuContent.swift
new file mode 100644
index 00000000..9525bfa7
--- /dev/null
+++ b/macos/Sources/NylonApp/MenuContent.swift
@@ -0,0 +1,38 @@
+import AppKit
+import SwiftUI
+
+struct MenuContent: View {
+    @ObservedObject var store: NodeStore
+
+    var body: some View {
+        if let nodes = store.nodes {
+            ForEach(nodes, id: \.name) { NodeRow(node: $0) }
+        } else {
+            Text("Can't read \(store.path)")
+        }
+        Divider()
+        Button("Choose central.yaml…") { chooseCentral() }
+        Button("Quit") { NSApplication.shared.terminate(nil) }
+    }
+
+    private func chooseCentral() {
+        NSApp.activate() // a menu bar app runs in the background, so bring the picker to the front
+        let panel = NSOpenPanel()
+        if panel.runModal() == .OK, let url = panel.url {
+            store.choose(url.path)
+        }
+    }
+}
+
+// A node's name and IP. Clicking it copies the IP.
+struct NodeRow: View {
+    let node: Node
+
+    var body: some View {
+        Button("\(node.name)  \(node.address ?? "no address")") {
+            NSPasteboard.general.clearContents()
+            NSPasteboard.general.setString(node.address ?? "", forType: .string)
+        }
+        .disabled(node.address == nil)
+    }
+}
diff --git a/macos/Sources/NylonApp/NodeStore.swift b/macos/Sources/NylonApp/NodeStore.swift
new file mode 100644
index 00000000..d87c52d3
--- /dev/null
+++ b/macos/Sources/NylonApp/NodeStore.swift
@@ -0,0 +1,25 @@
+import Foundation
+
+// What the menu shows. Views read it; where the data comes from stays in here.
+// ObservableObject, since @State is a macro the Command Line Tools can't expand (no SwiftUI macro plugin).
+final class NodeStore: ObservableObject {
+    @Published private(set) var path = ""
+    @Published private(set) var nodes: [Node]? // nil when central.yaml can't be read
+
+    // A path picked earlier or passed as `-central <path>` (both land in UserDefaults), else ./central.yaml like `nylon run`
+    init() {
+        load(UserDefaults.standard.string(forKey: "central") ?? "central.yaml")
+    }
+
+    // Picked from the menu, so remember it for the next launch.
+    func choose(_ path: String) {
+        UserDefaults.standard.set(path, forKey: "central")
+        load(path)
+    }
+
+    private func load(_ path: String) {
+        // absolute and with ~ expanded, so "Can't read" says where it looked
+        self.path = URL(fileURLWithPath: NSString(string: path).expandingTildeInPath).path
+        nodes = try? readNodes(String(contentsOfFile: self.path, encoding: .utf8))
+    }
+}
diff --git a/macos/Sources/NylonApp/NylonApp.swift b/macos/Sources/NylonApp/NylonApp.swift
new file mode 100644
index 00000000..be9ac77a
--- /dev/null
+++ b/macos/Sources/NylonApp/NylonApp.swift
@@ -0,0 +1,18 @@
+import AppKit
+import SwiftUI
+
+@main
+struct MenuApp: App {
+    @StateObject private var store = NodeStore()
+
+    init() {
+        // menu bar only; without an app bundle it would otherwise start background-only
+        NSApplication.shared.setActivationPolicy(.accessory)
+    }
+
+    var body: some Scene {
+        MenuBarExtra("Nylon", systemImage: "network") {
+            MenuContent(store: store)
+        }
+    }
+}
diff --git a/macos/Tests/NylonAppTests/CentralTests.swift b/macos/Tests/NylonAppTests/CentralTests.swift
new file mode 100644
index 00000000..36d33930
--- /dev/null
+++ b/macos/Tests/NylonAppTests/CentralTests.swift
@@ -0,0 +1,35 @@
+import Testing
+@testable import NylonApp
+
+// Block and flow lists, prefix objects the app ignores, and a router with no addresses.
+@Test func readsNodes() throws {
+    let yaml = """
+    routers:
+      - id: alice
+        pubkey: k
+        endpoints: ["alice.example.com:57175"]
+        addresses:
+          - 10.0.0.1
+          - fd00::1
+        prefixes:
+          - type: static
+            prefix: 192.168.0.0/24
+      - id: relay
+        pubkey: k
+    clients:
+      - id: phone
+        pubkey: k
+        addresses: [10.0.0.20]
+    graph:
+      - alice, relay, phone
+    """
+    #expect(try readNodes(yaml) == [
+        Node(name: "alice", address: "10.0.0.1"),
+        Node(name: "relay", address: nil),
+        Node(name: "phone", address: "10.0.0.20"),
+    ])
+}
+
+@Test func rejectsMalformedYAML() {
+    #expect(throws: (any Error).self) { try readNodes("routers: [") }
+}