Latest version : 3.1.2

 Last updated on 2014-04-28T04:03:52.897Z

 Keywords : koa, middleware, router, route

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Router middleware for koa

Build Status Dependency Status NPM version

  • Express-style routing using app.get, app.put,, etc.
  • Named URL parameters and regexp captures.
  • String or regular expression route matching.
  • Named routes with URL generation.
  • Responds to OPTIONS requests with allowed methods.
  • Support for 405 Method Not Allowed and 501 Not Implemented.
  • Multiple route middleware.
  • Multiple routers.


koa-router is available using npm:

npm install koa-router


Require the router and mount the middleware:

var koa = require('koa')
  , router = require('koa-router')
  , app = koa();


After the router has been initialized you can register routes:

app.get('/users/:id', function *(next) {
  var user = yield User.findOne(;
  this.body = user;

Multiple routers

You can use multiple routers and sets of routes by omitting the app argument. For example, separate routers for two versions of an API:

var APIv1 = new Router();
var APIv2 = new Router();

APIv1.get('/sign-in', function *() {
  // ...

APIv2.get('/sign-in', function *() {
  // ...

app.use(mount('/v1', APIv1.middleware()));
app.use(mount('/v2', APIv2.middleware()));


The http methods (get, post, etc) return their Router instance, so routes can be chained as you're used to with express:

var api = new Router();

  .get('/foo', showFoo)
  .get('/bar', showBar)
  .post('/foo', createFoo);


Migrating from 2.x to 3.x

Resource routing was separated into the koa-resource-router module.

Router#verb([name, ]path, middleware[, middleware...])

Match URL patterns to callback functions or controller actions using router.verb(), where verb is one of the HTTP verbs such as router.get() or

app.get('/', function *(next) {
  this.body = 'Hello World!';
});'/users', function *(next) {
  // ...

app.put('/users/:id', function *(next) {
  // ...

app.del('/users/:id', function *(next) {
  // ...

Route paths will be translated to regular expressions used to match requests.

Query strings will not be considered when matching requests.

Named routes

Routes can optionally have names. This allows generation of URLs and easy renaming of URLs during development.

app.get('user', '/users/:id', function *(next) {
 // ...

app.url('user', 3);
// => "/users/3"

Multiple middleware

Multiple middleware may be given and are composed using koa-compose:

  function *(next) {
    this.user = yield User.findOne(;
    yield next;
  function *(next) {
    // => { id: 17, name: "Alex" }

URL parameters

Named route parameters are captured and added to ctx.params.

Capture groups from regular expression routes are also added to ctx.params, which is an array.

Named parameters
app.get('/:category/:title', function *(next) {
  // => [ category: 'programming', title: 'how-to-node' ]
Regular expression captures
app.get(^\/([^\/]+)\/([^\/]+)\/?$, function *(next) {
  // => [ 'programming', 'how-to-node' ]

Regular expressions

Control route matching exactly by specifying a regular expression instead of a path string when creating the route. For example, it might be useful to match date formats for a blog, such as /blog/2013-09-04:

app.get(/^\/blog\/\d{4}-\d{2}-\d{2}\/?$/i, function *(next) {
  // ...

Multiple methods

Create routes with multiple HTTP methods using router.register():

app.register('/', ['get', 'post'], function *(next) {
  // ...

Create route for all methods using router.all():

app.all('/', function *(next) {
  // ...

Router#redirect(source, destination, [code])

Redirect source to destination URL with optional 30x status code.

Both source and destination can be route names.

app.redirect('/login', 'sign-in');

This is equivalent to:

app.all('/login', function *() {
  this.status = 301;


Lookup route with given name. Returns the route or false.

Router#url(name, params)

Generate URL for route. Takes either map of named params or series of arguments (for regular expression routes).

Returns Error if no route is found with given name.

app.get('user', '/users/:id', function *(next) {
 // ...

app.url('user', 3);
// => "/users/3"

app.url('user', { id: 3 });
// => "/users/3"


Tests use mocha and can be run with npm:

npm test

MIT Licensed