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The one-liner node.js proxy middleware for connect, express, next.js and more

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Package description

What is http-proxy-middleware?

The http-proxy-middleware package is a Node.js package that provides an HTTP proxy as a middleware for use with Node.js applications, particularly in conjunction with frameworks like Express. It allows developers to easily set up proxy rules to forward requests to other servers, which is useful for tasks like API forwarding, logging, handling CORS, and more.

What are http-proxy-middleware's main functionalities?

Proxy requests

This feature allows you to proxy requests to another server. In this example, all requests to '/api' on the local server are forwarded to ''.

const { createProxyMiddleware } = require('http-proxy-middleware');

const apiProxy = createProxyMiddleware('/api', { target: '' });

app.use('/api', apiProxy);

Path Rewriting

This feature allows you to rewrite the path of the request URL before it gets proxied. In this example, the path '/api' is removed before the request is forwarded to ''.

const { createProxyMiddleware } = require('http-proxy-middleware');

const apiProxy = createProxyMiddleware('/api', {
  target: '',
  pathRewrite: { '^/api': '' }

app.use('/api', apiProxy);

Custom Routing Logic

This feature allows you to implement custom routing logic. In this example, only GET requests to paths starting with '/api' are proxied to ''.

const { createProxyMiddleware } = require('http-proxy-middleware');

const apiProxy = createProxyMiddleware((pathname, req) => {
  return pathname.match('^/api') && req.method === 'GET';
}, { target: '' });


Handling WebSockets

This feature allows you to proxy WebSocket connections. In this example, WebSocket connections to '/socket' are proxied to 'ws://'.

const { createProxyMiddleware } = require('http-proxy-middleware');

const wsProxy = createProxyMiddleware('/socket', {
  target: 'ws://',
  ws: true

app.use('/socket', wsProxy);

Other packages similar to http-proxy-middleware




This release contains some breaking changes.

Please read the V3 discussion or follow the guide.

  • feat(typescript): type improvements (#882)
  • chore(deps): update micromatch to 4.0.5
  • chore(package): bump devDependencies
  • feat(legacyCreateProxyMiddleware): show migration tips (#756)
  • feat(legacyCreateProxyMiddleware): adapter with v2 behavior (#754)
  • docs(proxy events): fix new syntax (#753)
  • feat(debug): improve troubleshooting (#752)
  • test(path-rewriter): improve coverage (#751)
  • feat(ejectPlugins): skip registering default plugins (#750)
  • refactor: logging [BREAKING CHANGE] (#749)
  • refactor(handlers): refactor to plugins [BREAKING CHANGE] (#745)
  • feat(plugins): add support for plugins (#732)
  • docs: fix v3 documentation
  • fix: server mounting [BREAKING CHANGE] (#731)
  • test(fixRequestBody): fix broken test
  • refactor: use node http base types [BREAKING CHANGE] (#730) (special thanks: @cdaringe & @devanshj)
  • feat(option): refactor context to pathFilter option [BREAKING CHANGE] (#722)
  • feat: remove shorthand usage [BREAKING CHANGE] (#716)




GitHub Workflow Status (with branch) Coveralls Known Vulnerabilities npm

Node.js proxying made simple. Configure proxy middleware with ease for connect, express, next.js and many more.

Powered by the popular Nodejitsu http-proxy. GitHub stars

⚠️ Note

This page is showing documentation for version v3.x.x (release notes)

See for details on how to migrate from v2.x.x to v3.x.x

If you're looking for older documentation. Go to:


Proxy /api requests to

:bulb: Tip: Set the option changeOrigin to true for name-based virtual hosted sites.

// javascript

const express = require('express');
const { createProxyMiddleware } = require('http-proxy-middleware');

const app = express();

    target: '',
    changeOrigin: true,


// proxy and change the base path from "/api" to "/secret"
// ->
// typescript

import * as express from 'express';
import { createProxyMiddleware, Filter, Options, RequestHandler } from 'http-proxy-middleware';

const app = express();

    target: '',
    changeOrigin: true,


// proxy and keep the same base path "/api"
// ->

All http-proxy options can be used, along with some extra http-proxy-middleware options.

Table of Contents


npm install --save-dev http-proxy-middleware

Basic usage

Create and configure a proxy middleware with: createProxyMiddleware(config).

const { createProxyMiddleware } = require('http-proxy-middleware');

const apiProxy = createProxyMiddleware({
  target: '',
  changeOrigin: true,

// 'apiProxy' is now ready to be used as middleware in a server.

Express Server Example

An example with express server.

// include dependencies
const express = require('express');
const { createProxyMiddleware } = require('http-proxy-middleware');

const app = express();

// create the proxy
/** @type {import('http-proxy-middleware/dist/types').RequestHandler<express.Request, express.Response>} */
const exampleProxy = createProxyMiddleware({
  target: '', // target host with the same base path
  changeOrigin: true, // needed for virtual hosted sites

// mount `exampleProxy` in web server
app.use('/api', exampleProxy);

app.use(path, proxy)

If you want to use the server's app.use path parameter to match requests. Use pathFilter option to further include/exclude requests which you want to proxy.

    target: '',
    changeOrigin: true,
    pathFilter: '/api/proxy-only-this-path',

app.use documentation:


http-proxy-middleware options:

pathFilter (string, []string, glob, []glob, function)

Narrow down which requests should be proxied. The path used for filtering is the request.url pathname. In Express, this is the path relative to the mount-point of the proxy.

  • path matching

    • createProxyMiddleware({...}) - matches any path, all requests will be proxied when pathFilter is not configured.
    • createProxyMiddleware({ pathFilter: '/api', ...}) - matches paths starting with /api
  • multiple path matching

    • createProxyMiddleware({ pathFilter: ['/api', '/ajax', '/someotherpath'], ...})
  • wildcard path matching

    For fine-grained control you can use wildcard matching. Glob pattern matching is done by micromatch. Visit micromatch or glob for more globbing examples.

    • createProxyMiddleware({ pathFilter: '**', ...}) matches any path, all requests will be proxied.
    • createProxyMiddleware({ pathFilter: '**/*.html', ...}) matches any path which ends with .html
    • createProxyMiddleware({ pathFilter: '/*.html', ...}) matches paths directly under path-absolute
    • createProxyMiddleware({ pathFilter: '/api/**/*.html', ...}) matches requests ending with .html in the path of /api
    • createProxyMiddleware({ pathFilter: ['/api/**', '/ajax/**'], ...}) combine multiple patterns
    • createProxyMiddleware({ pathFilter: ['/api/**', '!**/bad.json'], ...}) exclusion

    Note: In multiple path matching, you cannot use string paths and wildcard paths together.

  • custom matching

    For full control you can provide a custom function to determine which requests should be proxied or not.

     * @return {Boolean}
    const pathFilter = function (path, req) {
      return path.match('^/api') && req.method === 'GET';
    const apiProxy = createProxyMiddleware({
      target: '',
      pathFilter: pathFilter,

pathRewrite (object/function)

Rewrite target's url path. Object-keys will be used as RegExp to match paths.

// rewrite path
pathRewrite: {'^/old/api' : '/new/api'}

// remove path
pathRewrite: {'^/remove/api' : ''}

// add base path
pathRewrite: {'^/' : '/basepath/'}

// custom rewriting
pathRewrite: function (path, req) { return path.replace('/api', '/base/api') }

// custom rewriting, returning Promise
pathRewrite: async function (path, req) {
  const should_add_something = await httpRequestToDecideSomething(path);
  if (should_add_something) path += "something";
  return path;

router (object/function)

Re-target for specific requests.

// Use `host` and/or `path` to match requests. First match will be used.
// The order of the configuration matters.
router: {
    'integration.localhost:3000' : '',  // host only
    'staging.localhost:3000'     : '',  // host only
    'localhost:3000/api'         : '',  // host + path
    '/rest'                      : ''   // path only

// Custom router function (string target)
router: function(req) {
    return '';

// Custom router function (target object)
router: function(req) {
    return {
        protocol: 'https:', // The : is required
        host: '',
        port: 8004

// Asynchronous router function which returns promise
router: async function(req) {
    const url = await doSomeIO();
    return url;

plugins (Array)

const simpleRequestLogger = (proxyServer, options) => {
  proxyServer.on('proxyReq', (proxyReq, req, res) => {
    console.log(`[HPM] [${req.method}] ${req.url}`); // outputs: [HPM] GET /users

const config = {
  target: ``,
  changeOrigin: true,
  plugins: [simpleRequestLogger],

ejectPlugins (boolean) default: false

If you're not satisfied with the pre-configured plugins, you can eject them by configuring ejectPlugins: true.

NOTE: register your own error handlers to prevent server from crashing.

// eject default plugins and manually add them back

const {
  debugProxyErrorsPlugin, // subscribe to proxy errors to prevent server from crashing
  loggerPlugin, // log proxy events to a logger (ie. console)
  errorResponsePlugin, // return 5xx response on proxy error
  proxyEventsPlugin, // implements the "on:" option
} = require('http-proxy-middleware');

  target: ``,
  changeOrigin: true,
  ejectPlugins: true,
  plugins: [debugProxyErrorsPlugin, loggerPlugin, errorResponsePlugin, proxyEventsPlugin],

logger (Object)

Configure a logger to output information from http-proxy-middleware: ie. console, winston, pino, bunyan, log4js, etc...

Only info, warn, error are used internally for compatibility across different loggers.

If you use winston, make sure to enable interpolation:

See also logger recipes (recipes/ for more details.

  logger: console,

http-proxy events

Subscribe to http-proxy events with the on option:

  target: '',
  on: {
    proxyReq: (proxyReq, req, res) => {
      /* handle proxyReq */
    proxyRes: (proxyRes, req, res) => {
      /* handle proxyRes */
    error: (err, req, res) => {
      /* handle error */
  • option.on.error: function, subscribe to http-proxy's error event for custom error handling.

    function onError(err, req, res, target) {
      res.writeHead(500, {
        'Content-Type': 'text/plain',
      res.end('Something went wrong. And we are reporting a custom error message.');
  • option.on.proxyRes: function, subscribe to http-proxy's proxyRes event.

    function onProxyRes(proxyRes, req, res) {
      proxyRes.headers['x-added'] = 'foobar'; // add new header to response
      delete proxyRes.headers['x-removed']; // remove header from response
  • option.on.proxyReq: function, subscribe to http-proxy's proxyReq event.

    function onProxyReq(proxyReq, req, res) {
      // add custom header to request
      proxyReq.setHeader('x-added', 'foobar');
      // or log the req
  • option.on.proxyReqWs: function, subscribe to http-proxy's proxyReqWs event.

    function onProxyReqWs(proxyReq, req, socket, options, head) {
      // add custom header
      proxyReq.setHeader('X-Special-Proxy-Header', 'foobar');
  • function, subscribe to http-proxy's open event.

    function onOpen(proxySocket) {
      // listen for messages coming FROM the target here
      proxySocket.on('data', hybridParseAndLogMessage);
  • option.on.close: function, subscribe to http-proxy's close event.

    function onClose(res, socket, head) {
      // view disconnected websocket connections
      console.log('Client disconnected');

http-proxy options

The following options are provided by the underlying http-proxy library.

  • url string to be parsed with the url module

  • option.forward: url string to be parsed with the url module

  • option.agent: object to be passed to http(s).request (see Node's https agent and http agent objects)

  • option.ssl: object to be passed to https.createServer()

  • true/false: if you want to proxy websockets

  • option.xfwd: true/false, adds x-forward headers

  • true/false, if you want to verify the SSL Certs

  • option.toProxy: true/false, passes the absolute URL as the path (useful for proxying to proxies)

  • option.prependPath: true/false, Default: true - specify whether you want to prepend the target's path to the proxy path

  • option.ignorePath: true/false, Default: false - specify whether you want to ignore the proxy path of the incoming request (note: you will have to append / manually if required).

  • option.localAddress : Local interface string to bind for outgoing connections

  • option.changeOrigin: true/false, Default: false - changes the origin of the host header to the target URL

  • option.preserveHeaderKeyCase: true/false, Default: false - specify whether you want to keep letter case of response header key

  • option.auth : Basic authentication i.e. 'user:password' to compute an Authorization header.

  • option.hostRewrite: rewrites the location hostname on (301/302/307/308) redirects.

  • option.autoRewrite: rewrites the location host/port on (301/302/307/308) redirects based on requested host/port. Default: false.

  • option.protocolRewrite: rewrites the location protocol on (301/302/307/308) redirects to 'http' or 'https'. Default: null.

  • option.cookieDomainRewrite: rewrites domain of set-cookie headers. Possible values:

    • false (default): disable cookie rewriting

    • String: new domain, for example cookieDomainRewrite: "new.domain". To remove the domain, use cookieDomainRewrite: "".

    • Object: mapping of domains to new domains, use "*" to match all domains.
      For example keep one domain unchanged, rewrite one domain and remove other domains:

      cookieDomainRewrite: {
        "unchanged.domain": "unchanged.domain",
        "old.domain": "new.domain",
        "*": ""
  • option.cookiePathRewrite: rewrites path of set-cookie headers. Possible values:

    • false (default): disable cookie rewriting

    • String: new path, for example cookiePathRewrite: "/newPath/". To remove the path, use cookiePathRewrite: "". To set path to root use cookiePathRewrite: "/".

    • Object: mapping of paths to new paths, use "*" to match all paths. For example, to keep one path unchanged, rewrite one path and remove other paths:

      cookiePathRewrite: {
        "/unchanged.path/": "/unchanged.path/",
        "/old.path/": "/new.path/",
        "*": ""
  • option.headers: object, adds request headers. (Example: {host:''})

  • option.proxyTimeout: timeout (in millis) when proxy receives no response from target

  • option.timeout: timeout (in millis) for incoming requests

  • option.followRedirects: true/false, Default: false - specify whether you want to follow redirects

  • option.selfHandleResponse true/false, if set to true, none of the webOutgoing passes are called and it's your responsibility to appropriately return the response by listening and acting on the proxyRes event

  • option.buffer: stream of data to send as the request body. Maybe you have some middleware that consumes the request stream before proxying it on e.g. If you read the body of a request into a field called 'req.rawbody' you could restream this field in the buffer option:

    'use strict';
    const streamify = require('stream-array');
    const HttpProxy = require('http-proxy');
    const proxy = new HttpProxy();
    module.exports = (req, res, next) => {
          target: '',
          buffer: streamify(req.rawBody),


// verbose api
createProxyMiddleware({ pathFilter: '/', target: '', ws: true });

External WebSocket upgrade

In the previous WebSocket examples, http-proxy-middleware relies on a initial http request in order to listen to the http upgrade event. If you need to proxy WebSockets without the initial http request, you can subscribe to the server's http upgrade event manually.

const wsProxy = createProxyMiddleware({ target: 'ws://', changeOrigin: true });

const app = express();

const server = app.listen(3000);
server.on('upgrade', wsProxy.upgrade); // <-- subscribe to http 'upgrade'

Intercept and manipulate requests

Intercept requests from downstream by defining onProxyReq in createProxyMiddleware.

Currently the only pre-provided request interceptor is fixRequestBody, which is used to fix proxied POST requests when bodyParser is applied before this middleware.


const { createProxyMiddleware, fixRequestBody } = require('http-proxy-middleware');

const proxy = createProxyMiddleware({
   * Fix bodyParser
  on: {
    proxyReq: fixRequestBody,

Intercept and manipulate responses

Intercept responses from upstream with responseInterceptor. (Make sure to set selfHandleResponse: true)

Responses which are compressed with brotli, gzip and deflate will be decompressed automatically. The response will be returned as buffer (docs) which you can manipulate.

With buffer, response manipulation is not limited to text responses (html/css/js, etc...); image manipulation will be possible too. (example)

NOTE: responseInterceptor disables streaming of target's response.


const { createProxyMiddleware, responseInterceptor } = require('http-proxy-middleware');

const proxy = createProxyMiddleware({
   * IMPORTANT: avoid res.end being called automatically
  selfHandleResponse: true, // res.end() will be called internally by responseInterceptor()

   * Intercept response and replace 'Hello' with 'Goodbye'
  on: {
    proxyRes: responseInterceptor(async (responseBuffer, proxyRes, req, res) => {
      const response = responseBuffer.toString('utf8'); // convert buffer to string
      return response.replace('Hello', 'Goodbye'); // manipulate response and return the result

Check out interception recipes for more examples.

Node.js 17+: ECONNREFUSED issue with IPv6 and localhost (#705)

Node.js 17+ no longer prefers IPv4 over IPv6 for DNS lookups. E.g. It's not guaranteed that localhost will be resolved to – it might just as well be ::1 (or some other IP address).

If your target server only accepts IPv4 connections, trying to proxy to localhost will fail if resolved to ::1 (IPv6).

Ways to solve it:

  • Change target: "http://localhost" to target: "" (IPv4).
  • Change the target server to (also) accept IPv6 connections.
  • Add this flag when running node: node index.js --dns-result-order=ipv4first. (Not recommended.)

Note: There’s a thing called Happy Eyeballs which means connecting to both IPv4 and IPv6 in parallel, which Node.js doesn’t have, but explains why for example curl can connect.


Configure the DEBUG environment variable enable debug logging.

See debug project for more options.

DEBUG=http-proxy-middleware* node server.js

$ http-proxy-middleware proxy created +0ms
$ http-proxy-middleware proxying request to target: '' +359ms

Working examples

View and play around with working examples.


View the recipes for common use cases.

Compatible servers

http-proxy-middleware is compatible with the following servers:

Sample implementations can be found in the server recipes.


Run the test suite:

# install dependencies
$ yarn

# linting
$ yarn lint
$ yarn lint:fix

# building (compile typescript to js)
$ yarn build

# unit tests
$ yarn test

# code coverage
$ yarn cover

# check spelling mistakes
$ yarn spellcheck



The MIT License (MIT)

Copyright (c) 2015-2022 Steven Chim



Last updated on 01 Apr 2024

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