diff --git a/packages/shorebird_cli/lib/src/auth/auth.dart b/packages/shorebird_cli/lib/src/auth/auth.dart
index 4f9c0837..c253a5f2 100644
--- a/packages/shorebird_cli/lib/src/auth/auth.dart
+++ b/packages/shorebird_cli/lib/src/auth/auth.dart
@@ -52,14 +52,9 @@ class Auth {
     final shorebirdConfigDir = _shorebirdConfigDir;
     if (shorebirdConfigDir == null) return;
 
-    final sessionFile = File(p.join(shorebirdConfigDir, _sessionFileName))
-      ..createSync(recursive: true);
-
-    if (!sessionFile.existsSync()) {
-      sessionFile.createSync(recursive: true);
-    }
-
-    sessionFile.writeAsStringSync(json.encode(session.toJson()));
+    File(p.join(shorebirdConfigDir, _sessionFileName))
+      ..createSync(recursive: true)
+      ..writeAsStringSync(json.encode(session.toJson()));
   }
 
   void _clearSession() {
diff --git a/packages/shorebird_code_push_api_client/example/main.dart b/packages/shorebird_code_push_api_client/example/main.dart
new file mode 100644
index 00000000..384624bb
--- /dev/null
+++ b/packages/shorebird_code_push_api_client/example/main.dart
@@ -0,0 +1,13 @@
+// ignore_for_file: unused_local_variable
+
+import 'package:shorebird_code_push_api_client/src/shorebird_code_push_api_client.dart';
+
+Future<void> main() async {
+  final client = ShorebirdCodePushApiClient(apiKey: '<API KEY>');
+
+  // Download the latest engine revision.
+  final engine = await client.downloadEngine('latest');
+
+  // Create a new release.
+  await client.createRelease('path/to/release/libapp.so');
+}
diff --git a/packages/shorebird_code_push_api_client/lib/src/shorebird_code_push_api_client.dart b/packages/shorebird_code_push_api_client/lib/src/shorebird_code_push_api_client.dart
index 522947bb..4aef682a 100644
--- a/packages/shorebird_code_push_api_client/lib/src/shorebird_code_push_api_client.dart
+++ b/packages/shorebird_code_push_api_client/lib/src/shorebird_code_push_api_client.dart
@@ -1,4 +1,5 @@
 import 'dart:io';
+import 'dart:typed_data';
 
 import 'package:http/http.dart' as http;
 
@@ -7,14 +8,21 @@ import 'package:http/http.dart' as http;
 /// {@endtemplate}
 class ShorebirdCodePushApiClient {
   /// {@macro shorebird_code_push_api_client}
-  ShorebirdCodePushApiClient({http.Client? httpClient, Uri? hostedUri})
-      : _httpClient = httpClient ?? http.Client(),
+  ShorebirdCodePushApiClient({
+    required String apiKey,
+    http.Client? httpClient,
+    Uri? hostedUri,
+  })  : _apiKey = apiKey,
+        _httpClient = httpClient ?? http.Client(),
         _hostedUri = hostedUri ??
             Uri.https('shorebird-code-push-api-cypqazu4da-uc.a.run.app');
 
+  final String _apiKey;
   final http.Client _httpClient;
   final Uri _hostedUri;
 
+  Map<String, String> get _apiKeyHeader => {'x-api-key': _apiKey};
+
   /// Upload the artifact at [path] to the
   /// Shorebird CodePush API as a new release.
   Future<void> createRelease(String path) async {
@@ -24,10 +32,28 @@ class ShorebirdCodePushApiClient {
     );
     final file = await http.MultipartFile.fromPath('file', path);
     request.files.add(file);
+    request.headers.addAll(_apiKeyHeader);
     final response = await _httpClient.send(request);
 
     if (response.statusCode != HttpStatus.created) {
       throw Exception('${response.statusCode} ${response.reasonPhrase}');
     }
   }
+
+  /// Download the specified revision of the shorebird engine.
+  Future<Uint8List> downloadEngine(String revision) async {
+    final request = http.Request(
+      'GET',
+      Uri.parse('$_hostedUri/api/v1/engines/$revision'),
+    );
+    request.headers.addAll(_apiKeyHeader);
+
+    final response = await _httpClient.send(request);
+
+    if (response.statusCode != HttpStatus.ok) {
+      throw Exception('${response.statusCode} ${response.reasonPhrase}');
+    }
+
+    return response.stream.toBytes();
+  }
 }
diff --git a/packages/shorebird_code_push_api_client/test/src/shorebird_code_push_api_client_test.dart b/packages/shorebird_code_push_api_client/test/src/shorebird_code_push_api_client_test.dart
index 1fcde73b..c589dd19 100644
--- a/packages/shorebird_code_push_api_client/test/src/shorebird_code_push_api_client_test.dart
+++ b/packages/shorebird_code_push_api_client/test/src/shorebird_code_push_api_client_test.dart
@@ -13,6 +13,8 @@ class _FakeBaseRequest extends Fake implements http.BaseRequest {}
 
 void main() {
   group('ShorebirdCodePushApiClient', () {
+    const apiKey = 'api-key';
+
     late http.Client httpClient;
     late ShorebirdCodePushApiClient shorebirdCodePushApiClient;
 
@@ -23,12 +25,13 @@ void main() {
     setUp(() {
       httpClient = _MockHttpClient();
       shorebirdCodePushApiClient = ShorebirdCodePushApiClient(
+        apiKey: apiKey,
         httpClient: httpClient,
       );
     });
 
     test('can be instantiated', () {
-      expect(ShorebirdCodePushApiClient(), isNotNull);
+      expect(ShorebirdCodePushApiClient(apiKey: apiKey), isNotNull);
     });
 
     group('createRelease', () {
@@ -71,5 +74,44 @@ void main() {
         );
       });
     });
+
+    group('downloadEngine', () {
+      const engineRevision = 'engine-revision';
+      test('throws an exception if the http request fails', () async {
+        when(() => httpClient.send(any())).thenAnswer((_) async {
+          return http.StreamedResponse(
+            Stream.empty(),
+            400,
+          );
+        });
+
+        expect(
+          shorebirdCodePushApiClient.downloadEngine(engineRevision),
+          throwsA(isA<Exception>()),
+        );
+      });
+
+      test('sends a request to the correct url', () async {
+        when(() => httpClient.send(any())).thenAnswer((_) async {
+          return http.StreamedResponse(
+            Stream.empty(),
+            HttpStatus.ok,
+          );
+        });
+
+        await shorebirdCodePushApiClient.downloadEngine(engineRevision);
+
+        final request = verify(() => httpClient.send(captureAny()))
+            .captured
+            .single as http.Request;
+
+        expect(
+          request.url,
+          Uri.parse(
+            'https://shorebird-code-push-api-cypqazu4da-uc.a.run.app/api/v1/engines/$engineRevision',
+          ),
+        );
+      });
+    });
   });
 }