Default 404 Pagelet used if the router cannot dispatch to any route

Usage no npm install needed!

<script type="module">
  import 04Pagelet from 'https://cdn.skypack.dev/404-pagelet';


404 Pagelet

Version npmBuild StatusDependenciesCoverage Status

This Pagelet is responsible for displaying server errors. By default the 404 Pagelet is provided with BigPipe. However, if you need a custom 404 you can extend this Pagelet. For example to change the default view.


The 404 Pagelet is distributed through the node package manager (npm).

npm install --save 404-pagelet


Got stuck? Or can't wrap your head around a concept or just want some feedback, we got a dedicated IRC channel for that on Freenode:

  • IRC Server: irc.freenode.net
  • IRC Room: #bigpipe

Still stuck? Create an issue. Every question you have is a bug in our documentation and that should be corrected. So please, don't hesitate to create issues, many of them.


In this example the 404 Pagelet is extended with a custom view. BigPipe will automatically discover this extended version if it is provided to BigPipe alongside the other pagelets.

'use strict';

// Extend the 404 Pagelet with a custom view.
var Fourofour = require('404-pagelet').extend({
  view: '/path/to/my/custom-view.html'

// Initialise BigPipe server.
var pipe = require('bigpipe').createServer(2000, {
  pagelets: [ Fourofour, ... ]


The library makes use the diagnostics module from Pagelet. To display the 404 Pagelet specific debug messages, supply the following before running the program or

DEBUG=pagelet:404 node ...


Tests are automatically run on Travis CI to ensure that everything is functioning as intended. For local development we automatically install a pre-commit hook that runs the npm test command every time you commit changes. This ensures that we don't push any broken code in to this project.

To run tests locally, make sure the development dependencies are installed.

npm test
npm run coverage


404-pagelet is released under MIT.