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Custom Server


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You can use the custom server feature if you need websocket support or some other direct control over the web server itself.


  1. Add a server.ts or server.js file in your project root. Or you can use server/index.js or server/index.ts. See below for an example server.
  2. Now blitz dev and blitz start will automatically detect and use your custom server.


Here's an example custom server:

// server.ts
import blitz from "blitz/custom-server"
import { createServer } from "http"
import { parse } from "url"
import { log } from "next/dist/server/lib/logging"

const { PORT = "3000" } = process.env
const dev = process.env.NODE_ENV !== "production"
const app = blitz({ dev })
const handle = app.getRequestHandler()

app.prepare().then(() => {
  createServer((req, res) => {
    // Be sure to pass `true` as the second argument to `url.parse`.
    // This tells it to parse the query portion of the URL.
    const parsedUrl = parse(req.url!, true)
    const { pathname } = parsedUrl

    if (pathname === "/hello") {

    if (pathname === "/a") {
      // renders app/pages/a.tsx
      app.render(req, res, "/a", query)

    handle(req, res, parsedUrl)
  }).listen(PORT, () => {
    log.success(`Ready on http://localhost:${PORT}`)

The above blitz/custom-server import is a function that receives an object with the following options:

  • dev: Boolean - Whether or not to launch Blitz in dev mode. Defaults to false
  • dir: String - Location of the Blitz project. Defaults to '.'
  • quiet: Boolean - Hide error messages containing server information. Defaults to false
  • conf: object - Defaults to {}

The returned app can then be used to let Blitz handle requests as required.

Disabling file-system routing

By default, blitz will serve each file pages folders under a pathname matching the filename. If your project uses a custom server, this behavior may result in the same content being served from multiple paths, which can present problems with SEO and UX.

To disable this behavior and prevent routing based on files in pages, open blitz.config.js and disable the useFileSystemPublicRoutes config:

module.exports = {
  useFileSystemPublicRoutes: false,

Note that useFileSystemPublicRoutes disables filename routes from SSR; client-side routing may still access those paths. When using this option, you should guard against navigation to routes you do not want programmatically.

You may also wish to configure the client-side router to disallow client-side redirects to filename routes; for that refer to router.beforePopState.

Disabling hot reloading in development

The default value for customServer.hotReload is true. Should you need to disable hot reloading for your custom server, you can change the value of it to false.

module.exports = {
  customServer: {
    hotReload: false,

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