diff --git a/composer.json b/composer.json
new file mode 100644
index 0000000..c528ada
--- /dev/null
+++ b/composer.json
@@ -0,0 +1,28 @@
+{
+  "name": "google/auth",
+  "type": "library",
+  "description": "Google Auth Library for PHP",
+  "keywords": ["google", "oauth2", "authentication"],
+  "homepage": "http://github.com/google/google-auth-library-php",
+  "license": "Apache-2.0",
+  "require": {
+    "php": ">=5.4",
+    "firebase/php-jwt": "~2.0|~3.0|~4.0",
+    "guzzlehttp/guzzle": "~5.3|~6.0",
+    "guzzlehttp/psr7": "~1.2",
+    "psr/http-message": "^1.0",
+    "psr/cache": "^1.0"
+  },
+  "require-dev": {
+    "phpunit/phpunit": "3.7.*",
+    "friendsofphp/php-cs-fixer": "^1.11"
+  },
+  "autoload": {
+    "classmap": [
+      "src/"
+    ],
+    "psr-4": {
+      "Google\\Auth\\": "src"
+    }
+  }
+}