diff --git a/src/core/config.js b/src/core/config.js
index c42625778..7b72adfae 100644
--- a/src/core/config.js
+++ b/src/core/config.js
@@ -19,6 +19,7 @@ const config = merge(
     executeScript: null,
     noEmoji: false,
     ga: '',
+    ext: '.md',
     mergeNavbar: false,
     formatUpdated: '',
     externalLinkTarget: '_blank',
@@ -43,9 +44,9 @@ if (script) {
     }
   }
 
-  if (config.loadSidebar === true) config.loadSidebar = '_sidebar.md'
-  if (config.loadNavbar === true) config.loadNavbar = '_navbar.md'
-  if (config.coverpage === true) config.coverpage = '_coverpage.md'
+  if (config.loadSidebar === true) config.loadSidebar = '_sidebar' + config.ext
+  if (config.loadNavbar === true) config.loadNavbar = '_navbar' + config.ext
+  if (config.coverpage === true) config.coverpage = '_coverpage' + config.ext
   if (config.repo === true) config.repo = ''
   if (config.name === true) config.name = ''
 }
diff --git a/src/core/fetch/index.js b/src/core/fetch/index.js
index 045089864..ac1a908ed 100644
--- a/src/core/fetch/index.js
+++ b/src/core/fetch/index.js
@@ -81,10 +81,10 @@ export function fetchMixin (proto) {
           path = coverpage
         }
       } else if (Array.isArray(coverpage)) {
-        path = coverpage.indexOf(routePath) > -1 && '_coverpage.md'
+        path = coverpage.indexOf(routePath) > -1 && '_coverpage'
       } else {
         const cover = coverpage[routePath]
-        path = cover === true ? '_coverpage.md' : cover
+        path = cover === true ? '_coverpage' : cover
       }
 
       this.coverEnable = !!path
diff --git a/src/core/router/history/abstract.js b/src/core/router/history/abstract.js
index d608efe12..0846f2ba8 100644
--- a/src/core/router/history/abstract.js
+++ b/src/core/router/history/abstract.js
@@ -1,6 +1,5 @@
 import { History } from './base'
-import { parseQuery, stringifyQuery, cleanPath } from '../util'
-import { merge } from '../../util/core'
+import { parseQuery } from '../util'
 
 export class AbstractHistory extends History {
   constructor (config) {
@@ -23,17 +22,4 @@ export class AbstractHistory extends History {
       query: parseQuery(query)
     }
   }
-
-  toURL (path, params, currentRoute) {
-    const local = currentRoute && path[0] === '#'
-    const route = this.parse(path)
-
-    route.query = merge({}, route.query, params)
-    path = route.path + stringifyQuery(route.query)
-    path = path.replace(/\.md(\?)|\.md$/, '$1')
-
-    if (local) path = currentRoute + path
-
-    return cleanPath('/' + path)
-  }
 }
diff --git a/src/core/router/history/base.js b/src/core/router/history/base.js
index 055073b61..0a0ccd357 100644
--- a/src/core/router/history/base.js
+++ b/src/core/router/history/base.js
@@ -1,5 +1,11 @@
-import { getPath, isAbsolutePath } from '../util'
-import { noop } from '../../util/core'
+import {
+  getPath,
+  isAbsolutePath,
+  stringifyQuery,
+  cleanPath,
+  replaceSlug
+} from '../util'
+import { noop, merge } from '../../util/core'
 
 const cached = {}
 
@@ -14,10 +20,10 @@ function getAlias (path, alias, last) {
     : path
 }
 
-function getFileName (path) {
-  return /\.(md|html)$/g.test(path)
+function getFileName (path, ext) {
+  return new RegExp(`\\.(${ext.replace(/^\./, '')}|html)$`, 'g').test(path)
     ? path
-    : /\/$/g.test(path) ? `${path}README.md` : `${path}.md`
+    : /\/$/g.test(path) ? `${path}README${ext}` : `${path}${ext}`
 }
 
 export class History {
@@ -34,10 +40,11 @@ export class History {
 
     const { config } = this
     const base = this.getBasePath()
+    const ext = typeof config.ext !== 'string' ? '.md' : config.ext
 
     path = config.alias ? getAlias(path, config.alias) : path
-    path = getFileName(path)
-    path = path === '/README.md' ? config.homepage || path : path
+    path = getFileName(path, ext)
+    path = path === `/README${ext}` ? config.homepage || path : path
     path = isAbsolutePath(path) ? path : getPath(base, path)
 
     if (isRelative) {
@@ -57,5 +64,20 @@ export class History {
 
   parse () {}
 
-  toURL () {}
+  toURL (path, params, currentRoute) {
+    const local = currentRoute && path[0] === '#'
+    const route = this.parse(replaceSlug(path))
+
+    route.query = merge({}, route.query, params)
+    path = route.path + stringifyQuery(route.query)
+    path = path.replace(/\.md(\?)|\.md$/, '$1')
+
+    if (local) {
+      const idIndex = currentRoute.indexOf('?')
+      path =
+        (idIndex > 0 ? currentRoute.substr(0, idIndex) : currentRoute) + path
+    }
+
+    return cleanPath('/' + path)
+  }
 }
diff --git a/src/core/router/history/hash.js b/src/core/router/history/hash.js
index 37858521d..04280c958 100644
--- a/src/core/router/history/hash.js
+++ b/src/core/router/history/hash.js
@@ -1,17 +1,13 @@
 import { History } from './base'
-import { merge, cached, noop } from '../../util/core'
+import { noop } from '../../util/core'
 import { on } from '../../util/dom'
-import { parseQuery, stringifyQuery, cleanPath } from '../util'
+import { parseQuery, cleanPath, replaceSlug } from '../util'
 
 function replaceHash (path) {
   const i = location.href.indexOf('#')
   location.replace(location.href.slice(0, i >= 0 ? i : 0) + '#' + path)
 }
 
-const replaceSlug = cached(path => {
-  return path.replace('#', '?id=')
-})
-
 export class HashHistory extends History {
   constructor (config) {
     super(config)
@@ -73,19 +69,6 @@ export class HashHistory extends History {
   }
 
   toURL (path, params, currentRoute) {
-    const local = currentRoute && path[0] === '#'
-    const route = this.parse(replaceSlug(path))
-
-    route.query = merge({}, route.query, params)
-    path = route.path + stringifyQuery(route.query)
-    path = path.replace(/\.md(\?)|\.md$/, '$1')
-
-    if (local) {
-      const idIndex = currentRoute.indexOf('?')
-      path =
-        (idIndex > 0 ? currentRoute.substr(0, idIndex) : currentRoute) + path
-    }
-
-    return cleanPath('#/' + path)
+    return '#' + super.toURL(path, params, currentRoute)
   }
 }
diff --git a/src/core/router/history/html5.js b/src/core/router/history/html5.js
index 7747a447f..6acefaf63 100644
--- a/src/core/router/history/html5.js
+++ b/src/core/router/history/html5.js
@@ -1,7 +1,7 @@
 import { History } from './base'
-import { merge, noop } from '../../util/core'
+import { noop } from '../../util/core'
 import { on } from '../../util/dom'
-import { parseQuery, stringifyQuery, getPath, cleanPath } from '../util'
+import { parseQuery, getPath } from '../util'
 
 export class HTML5History extends History {
   constructor (config) {
@@ -62,17 +62,4 @@ export class HTML5History extends History {
       query: parseQuery(query)
     }
   }
-
-  toURL (path, params, currentRoute) {
-    const local = currentRoute && path[0] === '#'
-    const route = this.parse(path)
-
-    route.query = merge({}, route.query, params)
-    path = route.path + stringifyQuery(route.query)
-    path = path.replace(/\.md(\?)|\.md$/, '$1')
-
-    if (local) path = currentRoute + path
-
-    return cleanPath('/' + path)
-  }
 }
diff --git a/src/core/router/util.js b/src/core/router/util.js
index d3ce9a83c..84219b6fa 100644
--- a/src/core/router/util.js
+++ b/src/core/router/util.js
@@ -54,3 +54,7 @@ export const getParentPath = cached(path => {
 export const cleanPath = cached(path => {
   return path.replace(/^\/+/, '/').replace(/([^:])\/{2,}/g, '$1/')
 })
+
+export const replaceSlug = cached(path => {
+  return path.replace('#', '?id=')
+})