diff --git a/crates/browser/src/main.rs b/crates/browser/src/main.rs
index 7ad856c..1bdd079 100644
--- a/crates/browser/src/main.rs
+++ b/crates/browser/src/main.rs
@@ -1,3 +1,16 @@
+use we_platform::appkit;
+
 fn main() {
-    println!("we: a web browser");
+    let _pool = appkit::AutoreleasePool::new();
+
+    let app = appkit::App::shared();
+    app.set_activation_policy(appkit::NS_APPLICATION_ACTIVATION_POLICY_REGULAR);
+
+    appkit::install_app_delegate(&app);
+
+    let window = appkit::create_standard_window("we");
+    window.make_key_and_order_front();
+
+    app.activate();
+    app.run();
 }
diff --git a/crates/platform/src/appkit.rs b/crates/platform/src/appkit.rs
new file mode 100644
index 0000000..667b759
--- /dev/null
+++ b/crates/platform/src/appkit.rs
@@ -0,0 +1,350 @@
+//! AppKit FFI bindings for macOS window creation.
+//!
+//! Provides wrappers around NSApplication, NSWindow, NSAutoreleasePool, and
+//! NSView for opening native macOS windows.
+//!
+//! # Safety
+//!
+//! This module contains `unsafe` code for FFI with AppKit.
+//! The `platform` crate is one of the few crates where `unsafe` is permitted.
+
+use crate::cf::CfString;
+use crate::objc::{Class, Id, Imp, Sel};
+use crate::{class, msg_send};
+use std::os::raw::c_void;
+
+// ---------------------------------------------------------------------------
+// AppKit framework link
+// ---------------------------------------------------------------------------
+
+#[link(name = "AppKit", kind = "framework")]
+extern "C" {}
+
+// ---------------------------------------------------------------------------
+// Geometry types matching AppKit's expectations
+// ---------------------------------------------------------------------------
+
+/// `NSRect` / `CGRect` — a rectangle defined by origin and size.
+#[repr(C)]
+#[derive(Debug, Clone, Copy)]
+pub struct NSRect {
+    pub origin: NSPoint,
+    pub size: NSSize,
+}
+
+/// `NSPoint` / `CGPoint` — a point in 2D space.
+#[repr(C)]
+#[derive(Debug, Clone, Copy)]
+pub struct NSPoint {
+    pub x: f64,
+    pub y: f64,
+}
+
+/// `NSSize` / `CGSize` — a 2D size.
+#[repr(C)]
+#[derive(Debug, Clone, Copy)]
+pub struct NSSize {
+    pub width: f64,
+    pub height: f64,
+}
+
+impl NSRect {
+    /// Create a new rectangle.
+    pub fn new(x: f64, y: f64, width: f64, height: f64) -> NSRect {
+        NSRect {
+            origin: NSPoint { x, y },
+            size: NSSize { width, height },
+        }
+    }
+}
+
+// ---------------------------------------------------------------------------
+// NSWindow style mask constants
+// ---------------------------------------------------------------------------
+
+/// Window has a title bar.
+pub const NS_WINDOW_STYLE_MASK_TITLED: u64 = 1 << 0;
+/// Window has a close button.
+pub const NS_WINDOW_STYLE_MASK_CLOSABLE: u64 = 1 << 1;
+/// Window can be minimized.
+pub const NS_WINDOW_STYLE_MASK_MINIATURIZABLE: u64 = 1 << 2;
+/// Window can be resized.
+pub const NS_WINDOW_STYLE_MASK_RESIZABLE: u64 = 1 << 3;
+
+// ---------------------------------------------------------------------------
+// NSBackingStoreType constants
+// ---------------------------------------------------------------------------
+
+/// Buffered backing store (the standard for modern macOS).
+pub const NS_BACKING_STORE_BUFFERED: u64 = 2;
+
+// ---------------------------------------------------------------------------
+// NSApplicationActivationPolicy constants
+// ---------------------------------------------------------------------------
+
+/// Regular application that appears in the Dock and may have a menu bar.
+pub const NS_APPLICATION_ACTIVATION_POLICY_REGULAR: i64 = 0;
+
+// ---------------------------------------------------------------------------
+// NSAutoreleasePool
+// ---------------------------------------------------------------------------
+
+/// RAII wrapper for `NSAutoreleasePool`.
+///
+/// Creates a pool on construction and drains it on drop. Required for any
+/// Objective-C code that creates autoreleased objects.
+pub struct AutoreleasePool {
+    pool: Id,
+}
+
+impl Default for AutoreleasePool {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+impl AutoreleasePool {
+    /// Create a new autorelease pool.
+    pub fn new() -> AutoreleasePool {
+        let cls = class!("NSAutoreleasePool").expect("NSAutoreleasePool class not found");
+        let pool: *mut c_void = msg_send![cls.as_ptr(), alloc];
+        let pool: *mut c_void = msg_send![pool, init];
+        let pool = unsafe { Id::from_raw(pool as *mut _) }.expect("NSAutoreleasePool init failed");
+        AutoreleasePool { pool }
+    }
+}
+
+impl Drop for AutoreleasePool {
+    fn drop(&mut self) {
+        let _: *mut c_void = msg_send![self.pool.as_ptr(), drain];
+    }
+}
+
+// ---------------------------------------------------------------------------
+// NSApplication wrapper
+// ---------------------------------------------------------------------------
+
+/// Wrapper around `NSApplication`.
+pub struct App {
+    app: Id,
+}
+
+impl App {
+    /// Get the shared `NSApplication` instance.
+    ///
+    /// Must be called from the main thread. Creates the application object
+    /// if it doesn't already exist.
+    pub fn shared() -> App {
+        let cls = class!("NSApplication").expect("NSApplication class not found");
+        let app: *mut c_void = msg_send![cls.as_ptr(), sharedApplication];
+        let app = unsafe { Id::from_raw(app as *mut _) }.expect("sharedApplication returned nil");
+        App { app }
+    }
+
+    /// Set the application's activation policy.
+    ///
+    /// Use [`NS_APPLICATION_ACTIVATION_POLICY_REGULAR`] for a normal app that
+    /// appears in the Dock.
+    pub fn set_activation_policy(&self, policy: i64) {
+        let _: bool = msg_send![self.app.as_ptr(), setActivationPolicy: policy];
+    }
+
+    /// Activate the application, bringing it to the foreground.
+    pub fn activate(&self) {
+        let _: *mut c_void = msg_send![self.app.as_ptr(), activateIgnoringOtherApps: true];
+    }
+
+    /// Start the application's main event loop.
+    ///
+    /// This method does **not** return under normal circumstances.
+    pub fn run(&self) {
+        let _: *mut c_void = msg_send![self.app.as_ptr(), run];
+    }
+
+    /// Return the underlying Objective-C object.
+    pub fn id(&self) -> Id {
+        self.app
+    }
+}
+
+// ---------------------------------------------------------------------------
+// NSWindow wrapper
+// ---------------------------------------------------------------------------
+
+/// Wrapper around `NSWindow`.
+pub struct Window {
+    window: Id,
+}
+
+impl Window {
+    /// Create a new window with the given content rect, style mask, and backing.
+    ///
+    /// # Arguments
+    ///
+    /// * `rect` — The content rectangle (position and size).
+    /// * `style` — Bitwise OR of `NS_WINDOW_STYLE_MASK_*` constants.
+    /// * `backing` — Backing store type (use [`NS_BACKING_STORE_BUFFERED`]).
+    /// * `defer` — Whether to defer window device creation.
+    pub fn new(rect: NSRect, style: u64, backing: u64, defer: bool) -> Window {
+        let cls = class!("NSWindow").expect("NSWindow class not found");
+        let window: *mut c_void = msg_send![cls.as_ptr(), alloc];
+        let window: *mut c_void = msg_send![
+            window,
+            initWithContentRect: rect,
+            styleMask: style,
+            backing: backing,
+            defer: defer
+        ];
+        let window =
+            unsafe { Id::from_raw(window as *mut _) }.expect("NSWindow initWithContentRect failed");
+        Window { window }
+    }
+
+    /// Set the window's title.
+    pub fn set_title(&self, title: &str) {
+        let cf_title = CfString::new(title).expect("failed to create CFString for title");
+        // CFStringRef is toll-free bridged to NSString*.
+        let _: *mut c_void = msg_send![self.window.as_ptr(), setTitle: cf_title.as_void_ptr()];
+    }
+
+    /// Make the window the key window and bring it to the front.
+    pub fn make_key_and_order_front(&self) {
+        let _: *mut c_void =
+            msg_send![self.window.as_ptr(), makeKeyAndOrderFront: std::ptr::null::<c_void>()];
+    }
+
+    /// Get the window's content view.
+    pub fn content_view(&self) -> Id {
+        let view: *mut c_void = msg_send![self.window.as_ptr(), contentView];
+        unsafe { Id::from_raw(view as *mut _) }.expect("contentView returned nil")
+    }
+
+    /// Return the underlying Objective-C object.
+    pub fn id(&self) -> Id {
+        self.window
+    }
+}
+
+// ---------------------------------------------------------------------------
+// App delegate for handling window close -> app termination
+// ---------------------------------------------------------------------------
+
+/// Install an application delegate that terminates the app when the last
+/// window is closed.
+///
+/// This creates a custom Objective-C class `WeAppDelegate` that implements
+/// `applicationShouldTerminateAfterLastWindowClosed:` returning `YES`.
+pub fn install_app_delegate(app: &App) {
+    // Only register the delegate class once.
+    if class!("WeAppDelegate").is_some() {
+        // Already registered, just create an instance and set it.
+        set_delegate(app);
+        return;
+    }
+
+    let superclass = class!("NSObject").expect("NSObject not found");
+    let delegate_class = Class::allocate(superclass, c"WeAppDelegate", 0)
+        .expect("failed to allocate WeAppDelegate class");
+
+    // applicationShouldTerminateAfterLastWindowClosed:
+    extern "C" fn should_terminate_after_last_window_closed(
+        _this: *mut c_void,
+        _sel: *mut c_void,
+        _app: *mut c_void,
+    ) -> bool {
+        true
+    }
+
+    let sel = Sel::register(c"applicationShouldTerminateAfterLastWindowClosed:");
+    delegate_class.add_method(
+        sel,
+        unsafe {
+            std::mem::transmute::<*const (), Imp>(
+                should_terminate_after_last_window_closed as *const (),
+            )
+        },
+        c"B@:@",
+    );
+
+    delegate_class.register();
+    set_delegate(app);
+}
+
+fn set_delegate(app: &App) {
+    let cls = class!("WeAppDelegate").expect("WeAppDelegate not found");
+    let delegate: *mut c_void = msg_send![cls.as_ptr(), alloc];
+    let delegate: *mut c_void = msg_send![delegate, init];
+    let _: *mut c_void = msg_send![app.id().as_ptr(), setDelegate: delegate];
+}
+
+// ---------------------------------------------------------------------------
+// Convenience: create a standard browser window
+// ---------------------------------------------------------------------------
+
+/// Create a standard window suitable for a browser.
+///
+/// Returns a window with title bar, close, minimize, and resize controls,
+/// centered at (200, 200), sized 800x600.
+pub fn create_standard_window(title: &str) -> Window {
+    let style = NS_WINDOW_STYLE_MASK_TITLED
+        | NS_WINDOW_STYLE_MASK_CLOSABLE
+        | NS_WINDOW_STYLE_MASK_MINIATURIZABLE
+        | NS_WINDOW_STYLE_MASK_RESIZABLE;
+
+    let rect = NSRect::new(200.0, 200.0, 800.0, 600.0);
+    let window = Window::new(rect, style, NS_BACKING_STORE_BUFFERED, false);
+    window.set_title(title);
+    window
+}
+
+// ---------------------------------------------------------------------------
+// Tests
+// ---------------------------------------------------------------------------
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn nsrect_new() {
+        let rect = NSRect::new(10.0, 20.0, 300.0, 400.0);
+        assert_eq!(rect.origin.x, 10.0);
+        assert_eq!(rect.origin.y, 20.0);
+        assert_eq!(rect.size.width, 300.0);
+        assert_eq!(rect.size.height, 400.0);
+    }
+
+    #[test]
+    fn style_mask_constants() {
+        // Verify the constants match AppKit's expected values.
+        assert_eq!(NS_WINDOW_STYLE_MASK_TITLED, 1);
+        assert_eq!(NS_WINDOW_STYLE_MASK_CLOSABLE, 2);
+        assert_eq!(NS_WINDOW_STYLE_MASK_MINIATURIZABLE, 4);
+        assert_eq!(NS_WINDOW_STYLE_MASK_RESIZABLE, 8);
+    }
+
+    #[test]
+    fn backing_store_constant() {
+        assert_eq!(NS_BACKING_STORE_BUFFERED, 2);
+    }
+
+    #[test]
+    fn activation_policy_constant() {
+        assert_eq!(NS_APPLICATION_ACTIVATION_POLICY_REGULAR, 0);
+    }
+
+    #[test]
+    fn autorelease_pool_create_and_drop() {
+        // Creating and dropping an autorelease pool should not crash.
+        let _pool = AutoreleasePool::new();
+    }
+
+    #[test]
+    fn combined_style_mask() {
+        let style = NS_WINDOW_STYLE_MASK_TITLED
+            | NS_WINDOW_STYLE_MASK_CLOSABLE
+            | NS_WINDOW_STYLE_MASK_MINIATURIZABLE
+            | NS_WINDOW_STYLE_MASK_RESIZABLE;
+        assert_eq!(style, 0b1111);
+    }
+}
diff --git a/crates/platform/src/lib.rs b/crates/platform/src/lib.rs
index 1139cc8..ddd494c 100644
--- a/crates/platform/src/lib.rs
+++ b/crates/platform/src/lib.rs
@@ -1,4 +1,5 @@
 //! Minimal macOS platform layer — Obj-C FFI, AppKit, CoreGraphics, Metal.
 
+pub mod appkit;
 pub mod cf;
 pub mod objc;
diff --git a/crates/platform/src/objc.rs b/crates/platform/src/objc.rs
index 916d739..9732241 100644
--- a/crates/platform/src/objc.rs
+++ b/crates/platform/src/objc.rs
@@ -306,7 +306,8 @@ macro_rules! msg_send {
         });
         let func: unsafe extern "C" fn(*mut std::os::raw::c_void, *mut std::os::raw::c_void) -> _
             = unsafe { std::mem::transmute($crate::objc::msg_send_fn()) };
-        unsafe { func($receiver as *mut std::os::raw::c_void, sel.as_ptr() as *mut std::os::raw::c_void) }
+        let receiver = $receiver as *mut std::os::raw::c_void;
+        unsafe { func(receiver, sel.as_ptr() as *mut std::os::raw::c_void) }
     }};
 
     // One argument: msg_send![receiver, selector: arg]
@@ -320,11 +321,13 @@ macro_rules! msg_send {
             *mut std::os::raw::c_void,
             _,
         ) -> _ = unsafe { std::mem::transmute($crate::objc::msg_send_fn()) };
+        let receiver = $receiver as *mut std::os::raw::c_void;
+        let arg = $arg;
         unsafe {
             func(
-                $receiver as *mut std::os::raw::c_void,
+                receiver,
                 sel.as_ptr() as *mut std::os::raw::c_void,
-                $arg,
+                arg,
             )
         }
     }};
@@ -341,12 +344,15 @@ macro_rules! msg_send {
             _,
             _,
         ) -> _ = unsafe { std::mem::transmute($crate::objc::msg_send_fn()) };
+        let receiver = $receiver as *mut std::os::raw::c_void;
+        let arg1 = $arg1;
+        let arg2 = $arg2;
         unsafe {
             func(
-                $receiver as *mut std::os::raw::c_void,
+                receiver,
                 sel.as_ptr() as *mut std::os::raw::c_void,
-                $arg1,
-                $arg2,
+                arg1,
+                arg2,
             )
         }
     }};
@@ -368,13 +374,17 @@ macro_rules! msg_send {
             _,
             _,
         ) -> _ = unsafe { std::mem::transmute($crate::objc::msg_send_fn()) };
+        let receiver = $receiver as *mut std::os::raw::c_void;
+        let arg1 = $arg1;
+        let arg2 = $arg2;
+        let arg3 = $arg3;
         unsafe {
             func(
-                $receiver as *mut std::os::raw::c_void,
+                receiver,
                 sel.as_ptr() as *mut std::os::raw::c_void,
-                $arg1,
-                $arg2,
-                $arg3,
+                arg1,
+                arg2,
+                arg3,
             )
         }
     }};
@@ -398,14 +408,19 @@ macro_rules! msg_send {
             _,
             _,
         ) -> _ = unsafe { std::mem::transmute($crate::objc::msg_send_fn()) };
+        let receiver = $receiver as *mut std::os::raw::c_void;
+        let arg1 = $arg1;
+        let arg2 = $arg2;
+        let arg3 = $arg3;
+        let arg4 = $arg4;
         unsafe {
             func(
-                $receiver as *mut std::os::raw::c_void,
+                receiver,
                 sel.as_ptr() as *mut std::os::raw::c_void,
-                $arg1,
-                $arg2,
-                $arg3,
-                $arg4,
+                arg1,
+                arg2,
+                arg3,
+                arg4,
             )
         }
     }};