diff --git a/bytes/bytes-tests.ts b/bytes/bytes-tests.ts
new file mode 100644
index 0000000000..4a981aee47
--- /dev/null
+++ b/bytes/bytes-tests.ts
@@ -0,0 +1,16 @@
+/// <reference path="./bytes.d.ts"/>
+
+import bytes = require('bytes');
+
+// 1024*1024 = 1048576
+console.log(bytes(104857));
+console.log(bytes(104857, { thousandsSeparator: ' ' }));
+
+console.log(bytes.format(104857));
+console.log(bytes.format(104857, { thousandsSeparator: ' ' }));
+
+console.log(bytes('1024kb'));
+console.log(bytes(1024));
+
+console.log(bytes.parse('1024kb'));
+console.log(bytes.parse(1024));
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diff --git a/bytes/bytes.d.ts b/bytes/bytes.d.ts
new file mode 100644
index 0000000000..d9946edf2f
--- /dev/null
+++ b/bytes/bytes.d.ts
@@ -0,0 +1,66 @@
+// Type definitions for bytes v2.1.0
+// Project: https://github.com/visionmedia/bytes.js
+// Definitions by: Zhiyuan Wang <https://github.com/danny8002/>
+// Definitions: https://github.com/borisyankov/DefinitelyTyped
+
+declare module 'bytes' {
+
+    interface IBytesFormatOptions {
+        thousandsSeparator: string
+    }
+
+    /**
+     *Convert the given value in bytes into a string.
+     *
+     * @param {number} value
+     * @param {{
+     *  thousandsSeparator: [string]
+     *  }} [options] bytes options.
+     *
+     * @returns {string}
+     */
+    function bytes(value: number, options?: IBytesFormatOptions): string;
+
+    /**
+     *Parse string to an integer in bytes.
+     *
+     * @param {string} value
+     * @returns {number}
+     */
+    function bytes(value: string): number;
+
+    module bytes {
+
+        /**
+         * Format the given value in bytes into a string.
+         * 
+         * If the value is negative, take Math.abs(). If it is a float,
+         * it is rounded.
+         * 
+         * @param {number} value
+         * @param {IBytesFormatOptions} [options]
+         */
+
+        function format(value: number, options?: IBytesFormatOptions): string;
+
+        /**
+         * Just return the input number value.
+         * 
+         * @param {number} value
+         * @return {number}
+         */
+        function parse(value: number): number;
+
+        /**
+         * Parse the string value into an integer in bytes.
+         * 
+         * If no unit is given, it is assumed the value is in bytes.
+         * 
+         * @param {string} value
+         * @return {number}
+         */
+        function parse(value: string): number;
+    }
+
+    export = bytes;
+}
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