diff --git a/docs/source/_data/guide_toc.yml b/docs/source/_data/guide_toc.yml
index d6e767962b..964e47e812 100644
--- a/docs/source/_data/guide_toc.yml
+++ b/docs/source/_data/guide_toc.yml
@@ -39,7 +39,7 @@ Advanced:
   Cluster Client: /advanced/cluster-client.html
   View Plugin: /advanced/view-plugin.html
 Community:
-  Plugin List: /plugins
+  Plugin List: /plugins/
   Contributing: /contributing.html
   Resource: /resource.html
   # Member Guide: /member_guide.html
diff --git a/lib/application.js b/lib/application.js
index 8927ce1a4f..36609eba59 100644
--- a/lib/application.js
+++ b/lib/application.js
@@ -189,13 +189,18 @@ class Application extends EggApplication {
   }
 
   /**
-   * The helper class, `app/helper` will be loaded to it's prototype,
-   * then you can use all method on `ctx.helper`
+   * reference to {@link Helper}
    * @member {Helper} Application#Helper
    */
   get Helper() {
     if (!this[HELPER]) {
-      this[HELPER] = class Helper extends this.BaseContextClass {};
+      /**
+       * The Helper class which can be used as utility function.
+       * Files from `${baseDir}/app/helper` will be loaded to the prototype of Helper,
+       * then you can use all method on `ctx.helper` that is a instance of Helper.
+       */
+      class Helper extends this.BaseContextClass {}
+      this[HELPER] = Helper;
     }
     return this[HELPER];
   }
diff --git a/lib/core/messenger.js b/lib/core/messenger.js
index b7a8cdca36..930a0ae28e 100644
--- a/lib/core/messenger.js
+++ b/lib/core/messenger.js
@@ -5,6 +5,9 @@ const is = require('is-type-of');
 const sendmessage = require('sendmessage');
 const EventEmitter = require('events');
 
+/**
+ * Communication between app worker and agent worker by IPC channel
+ */
 class Messenger extends EventEmitter {
 
   constructor() {
diff --git a/package.json b/package.json
index b0d693e007..fa21061952 100644
--- a/package.json
+++ b/package.json
@@ -58,8 +58,10 @@
     "egg-view-nunjucks": "^2.1.2",
     "eslint": "^3.19.0",
     "eslint-config-egg": "^4.2.0",
+    "findlinks": "^1.1.0",
     "formstream": "^1.1.0",
     "glob": "^7.1.2",
+    "koa-static": "^3.0.0",
     "mz-modules": "^1.0.0",
     "pedding": "^1.1.0",
     "spy": "^1.0.0",
diff --git a/test/doc.test.js b/test/doc.test.js
new file mode 100644
index 0000000000..4db07209c7
--- /dev/null
+++ b/test/doc.test.js
@@ -0,0 +1,30 @@
+'use strict';
+
+const path = require('path');
+const findlinks = require('findlinks');
+const assert = require('assert');
+const runscript = require('runscript');
+const utils = require('./utils');
+
+describe('test/doc.test.js', () => {
+
+  if (process.platform === 'win32') return;
+
+  let app;
+  before(function* () {
+    yield runscript('doctools build', { cwd: path.dirname(__dirname) });
+  });
+  before(function* () {
+    app = utils.cluster({
+      baseDir: 'apps/docapp',
+    });
+    app.coverage(false);
+    yield app.ready();
+  });
+  after(() => app.close());
+
+  it('should no broken url', function* () {
+    const result = yield findlinks({ src: app.url, logger: console });
+    assert(result.fail === 0);
+  });
+});
diff --git a/test/fixtures/apps/docapp/app/middleware/koastatic.js b/test/fixtures/apps/docapp/app/middleware/koastatic.js
new file mode 100644
index 0000000000..975e1bbd4b
--- /dev/null
+++ b/test/fixtures/apps/docapp/app/middleware/koastatic.js
@@ -0,0 +1,7 @@
+'use strict';
+
+const path = require('path');
+
+module.exports = () => {
+  return require('koa-static')(path.join(process.cwd(), 'run/doctools/public'));
+};
diff --git a/test/fixtures/apps/docapp/config/config.default.js b/test/fixtures/apps/docapp/config/config.default.js
new file mode 100644
index 0000000000..de6604be96
--- /dev/null
+++ b/test/fixtures/apps/docapp/config/config.default.js
@@ -0,0 +1,8 @@
+'use strict';
+
+const path = require('path');
+
+module.exports = {
+  keys: 'test key',
+  middleware: [ 'koastatic' ],
+};
diff --git a/test/fixtures/apps/docapp/package.json b/test/fixtures/apps/docapp/package.json
new file mode 100644
index 0000000000..08811b3e64
--- /dev/null
+++ b/test/fixtures/apps/docapp/package.json
@@ -0,0 +1,3 @@
+{
+  "name": "docapp"
+}