diff --git a/README.md b/README.md
index 1ead84bb8f..a3c0aa08d6 100755
--- a/README.md
+++ b/README.md
@@ -37,6 +37,7 @@ List of Definitions
 * [Angular UI Bootstrap](http://angular-ui.github.io/bootstrap) (by [Brian Surowiec](https://github.com/xt0rted))
 * [AppFramework](http://app-framework-software.intel.com/) (by [Kyo Ago](https://github.com/kyo-ago))
 * [Arbiter](http://arbiterjs.com/) (by [Arash Shakery](https://github.com/arash16))
+* [assert](https://github.com/Jxck/assert) (by [vvakame](https://github.com/vvakame))
 * [async](https://github.com/caolan/async) (by [Boris Yankov](https://github.com/borisyankov))
 * [Backbone.js](http://backbonejs.org/) (by [Boris Yankov](https://github.com/borisyankov))
 * [Backbone Relational](http://backbonerelational.org/) (by [Eirik Hoem](https://github.com/eirikhm))
diff --git a/assert/assert-tests.ts b/assert/assert-tests.ts
new file mode 100644
index 0000000000..b01703e4d3
--- /dev/null
+++ b/assert/assert-tests.ts
@@ -0,0 +1,19 @@
+/// <reference path="./assert.d.ts" />
+
+assert(1 + 1 - 2 === 0, "The universe isn't how it should.");
+
+assert.deepEqual({ x: { y: 3 } }, { x: { y: 3 } }, "DEEP WENT DERP");
+
+assert.equal(3, "3", "uses == comparator");
+
+assert.notStrictEqual(2, "2", "uses === comparator");
+
+assert.throws(() => {
+    throw "a hammer at your face";
+}, undefined, "DODGED IT");
+
+assert.doesNotThrow(() => {
+    if (false) {
+        throw "a hammer at your face";
+    }
+}, undefined, "What the...*crunch*");
diff --git a/assert/assert.d.ts b/assert/assert.d.ts
new file mode 100644
index 0000000000..b54eae7fae
--- /dev/null
+++ b/assert/assert.d.ts
@@ -0,0 +1,53 @@
+// Type definitions for assert and power-assert
+// Project: https://github.com/Jxck/assert
+// Project: https://github.com/twada/power-assert
+// Definitions by: vvakame <https://github.com/vvakame>
+// Definitions: https://github.com/borisyankov/DefinitelyTyped
+
+// copy from assert external module in node.d.ts
+
+function assert(value:any, message?:string):void;
+module assert {
+    export class AssertionError implements Error {
+        name:string;
+        message:string;
+        actual:any;
+        expected:any;
+        operator:string;
+        generatedMessage:boolean;
+
+        constructor(options?:{message?: string; actual?: any; expected?: any; operator?: string; stackStartFunction?: Function});
+    }
+
+    export function fail(actual?:any, expected?:any, message?:string, operator?:string):void;
+
+    export function ok(value:any, message?:string):void;
+
+    export function equal(actual:any, expected:any, message?:string):void;
+
+    export function notEqual(actual:any, expected:any, message?:string):void;
+
+    export function deepEqual(actual:any, expected:any, message?:string):void;
+
+    export function notDeepEqual(acutal:any, expected:any, message?:string):void;
+
+    export function strictEqual(actual:any, expected:any, message?:string):void;
+
+    export function notStrictEqual(actual:any, expected:any, message?:string):void;
+
+    export var throws:{
+        (block:Function, message?:string): void;
+        (block:Function, error:Function, message?:string): void;
+        (block:Function, error:RegExp, message?:string): void;
+        (block:Function, error:(err:any) => boolean, message?:string): void;
+    };
+
+    export var doesNotThrow:{
+        (block:Function, message?:string): void;
+        (block:Function, error:Function, message?:string): void;
+        (block:Function, error:RegExp, message?:string): void;
+        (block:Function, error:(err:any) => boolean, message?:string): void;
+    };
+
+    export function ifError(value:any):void;
+}