Help secure Express apps with various HTTP headers
JavaScript
Latest commit 3ca8991 Jul 21, 2017 @EvanHahn EvanHahn 3.8.0

README.md

Helmet

npm version npm dependency status Build Status js-standard-style FOSSA Status

Helmet helps you secure your Express apps by setting various HTTP headers. It's not a silver bullet, but it can help!

Looking for a version of Helmet that supports the Koa framework?

Quick start

First, run npm install helmet --save for your app. Then, in an Express (or Connect) app:

var express = require('express')
var helmet = require('helmet')

var app = express()

app.use(helmet())

// ...

It's best to use Helmet early in your middleware stack so that its headers are sure to be set.

You can also use its pieces individually:

app.use(helmet.noCache())
app.use(helmet.frameguard())

You can disable a middleware that's normally enabled by default. This will disable frameguard but include the other defaults.

app.use(helmet({
  frameguard: false
}))

You can also set options for a middleware. Setting options like this will always include the middleware, whether or not it's a default.

app.use(helmet({
  frameguard: {
    action: 'deny'
  }
}))

If you're using Express 3, make sure these middlewares are listed before app.router.

How it works

Helmet is a collection of 12 smaller middleware functions that set HTTP headers. Running app.use(helmet()) will not include all of these middleware functions by default.

Module Default?
contentSecurityPolicy for setting Content Security Policy
expectCt for handling Certificate Transparency
dnsPrefetchControl controls browser DNS prefetching
frameguard to prevent clickjacking
hidePoweredBy to remove the X-Powered-By header
hpkp for HTTP Public Key Pinning
hsts for HTTP Strict Transport Security
ieNoOpen sets X-Download-Options for IE8+
noCache to disable client-side caching
noSniff to keep clients from sniffing the MIME type
referrerPolicy to hide the Referer header
xssFilter adds some small XSS protections

You can see more in the documentation.