diff --git a/koa2/koa2-tests.ts b/koa2/koa2-tests.ts
new file mode 100644
index 0000000000..7c460d475f
--- /dev/null
+++ b/koa2/koa2-tests.ts
@@ -0,0 +1,20 @@
+/// <reference path="koa2.d.ts" />
+import * as Koa from "koa";
+
+const app = new Koa();
+
+app.use((ctx, next) => {
+  const start: any = new Date();
+  return next().then(() => {
+    const end: any = new Date();
+    const ms = end - start;
+    console.log(`${ctx.method} ${ctx.url} - ${ms}ms`);
+  });
+});
+
+// response
+app.use(ctx => {
+  ctx.body = "Hello World";
+});
+
+app.listen(3000);
diff --git a/koa2/koa2.d.ts b/koa2/koa2.d.ts
new file mode 100644
index 0000000000..0433e2b09b
--- /dev/null
+++ b/koa2/koa2.d.ts
@@ -0,0 +1,135 @@
+// Type definitions for Koa 2.x
+// Project: http://koajs.com
+// Definitions by: DavidCai1993 <https://github.com/DavidCai1993>
+// Definitions: https://github.com/borisyankov/DefinitelyTyped
+
+/* =================== USAGE ===================
+
+    import * as Koa from "koa"
+    const app = new Koa()
+
+ =============================================== */
+/// <reference path="../node/node.d.ts" />
+
+declare module "koa" {
+  import { EventEmitter } from "events";
+  import * as http from "http";
+  import * as net from "net";
+
+  interface IContext extends IRequest, IResponse {
+      body?: any;
+      request?: IRequest;
+      response?: IResponse;
+      originalUrl?: string;
+      state?: any;
+      name?: string;
+      cookies?: any;
+      writable?: Boolean;
+      respond?: Boolean;
+      app?: Koa;
+      req?: http.IncomingMessage;
+      res?: http.ServerResponse;
+      onerror(err: any): void;
+      toJSON(): any;
+      inspect(): any;
+      throw(): void;
+      assert(): void;
+  }
+
+  interface IRequest {
+      _querycache?: string;
+      app?: Koa;
+      req?: http.IncomingMessage;
+      res?: http.ServerResponse;
+      response?: IResponse;
+      ctx?: IContext;
+      headers?: any;
+      header?: any;
+      method?: string;
+      length?: any;
+      url?: string;
+      origin?: string;
+      originalUrl?: string;
+      href?: string;
+      path?: string;
+      querystring?: string;
+      query?: any;
+      search?: string;
+      idempotent?: Boolean;
+      socket?: net.Socket;
+      protocol?: string;
+      host?: string;
+      hostname?: string;
+      fresh?: Boolean;
+      stale?: Boolean;
+      charset?: string;
+      secure?: Boolean;
+      ips?: Array<string>;
+      ip?: string;
+      subdomains?: Array<string>;
+      accept?: any;
+      type?: string;
+      accepts?: () => any;
+      acceptsEncodings?: () => any;
+      acceptsCharsets?: () => any;
+      acceptsLanguages?: () => any;
+      is?: (types: any) => any;
+      toJSON?: () => any;
+      inspect?: () => any;
+      get?: (field: string) => string;
+  }
+
+  interface IResponse {
+      _body?: any;
+      _explicitStatus?: Boolean;
+      app?: Koa;
+      res?: http.ServerResponse;
+      req?: http.IncomingMessage;
+      ctx?: IContext;
+      request?: IRequest;
+      socket?: net.Socket;
+      header?: any;
+      headers?: any;
+      status?: number;
+      message?: string;
+      type?: string;
+      body?: any;
+      length?: any;
+      headerSent?: Boolean;
+      lastModified?: Date;
+      etag?: string;
+      writable?: Boolean;
+      is?: (types: any) => any;
+      redirect?: (url: string, alt: string) => void;
+      attachment?: (filename?: string) => void;
+      vary?: (field: string) => void;
+      get?: (field: string) => string;
+      set?: (field: any, val: any) => void;
+      remove?: (field: string) => void;
+      append?: (field: string, val: any) => void;
+      toJSON?: () => any;
+      inspect?: () => any;
+  }
+
+  class Koa extends EventEmitter {
+      keys: Array<string>;
+      subdomainOffset: number;
+      proxy: Boolean;
+      server: http.Server;
+      env: string;
+      context: IContext;
+      request: IRequest;
+      response: IResponse;
+      silent: Boolean;
+      constructor();
+      use(middleware: (ctx: IContext, next: Function) => any): Koa;
+      callback(): (req: http.IncomingMessage, res: http.ServerResponse) => void;
+      listen(port: number, callback?: Function): http.Server;
+      toJSON(): any;
+      inspect(): any;
+      onerror(err: any): void;
+  }
+
+  let K: typeof Koa;
+  export = K
+}