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fastify-jwt-webapp brings the security and simplicity of JSON Web Tokens to your fastify-based web apps, single- and multi-paged "traditional" applications are the target of this plugin, although it does not impose a server-side session to accomplish being "logged-in" from request to request. Rather, a JWT is simply stored in a client-side cookie and retrieved and verified with each request after successful login. This plugin does not assume your knowledge of JWTs themselves, but knowledge of the workflows involved, particularly as it relates to your provider, are assumed. (this plugin uses a /authorize -> authorization_code -> /oauth/token -> JWT-like workflow)

To see fastify-jwt-webapp in the wild check out my website.


npm install --save fastify-jwt-webapp


'use strict'


const fastify = require('fastify')({
  https: true,
  logger: {
    prettyPrint: true,
    level: 'trace'

const fjwt = require('fastify-jwt-webapp')

const config = require('./config')

async function main () {
  // just local TLS
  await fastify.register(require('fastify-tls-keygen'))
  // register the plugin and pass config (from examples/config.js)
  await fastify.register(fjwt, config.fjwt)

  // a homepage with a login link
  fastify.get('/', async function (req, reply) {
      .send('<a href="/login">Click here to log-in</a>')

  // a protected route that will simply display one's credentials
  fastify.get('/credentials', async function (req, reply) {
      credentials: req.credentials

  await fastify.listen(8443, 'localhost')

  .then(function() {
    console.log('server started')
  .catch(function (err) {


'use strict'

const config = {}

config.fjwt = {
  service: 'auth0',
  urlAuthorize: '',
  urlToken: '',
  urlJWKS: '',
  client_id: '',
  client_secret: '',
  redirect_uri: 'https://localhost:8443/callback',
  // the following is optional
  pathSuccessRedirect: '/credentials', // '/' by default
  pathExempt: [
  ], // ['/login', '/callback'] by default
  authorizationCallback: async function (jwtResponse, req, reply) {'hello from authorizationCallback!')'jwtResponse: %o', jwtResponse)

module.exports = config


Being "logged-in" is achieved by passing along the JWT along with each request, as is typical with APIs (via the Authorization header). fastify-jwt-webapp does this by storing the JWT in a cookie (, "token" by default). By default this cookie is Secure, meaning that it will only be sent by the browser back to your app if the connection is secure. To change this behavior set to false. DO NOT DO THIS IN PRODUCTION. YOU HAVE BEEN WARNED. To see cookie options please see lib/config.js.

Refresh Tokens

This plugin does not treat refresh tokens, but there's no reason that you couldn't implement this functionality yourself. #sorrynotsorry

JWKS Caching

Fetching the JWKS is by far the most taxing part of this whole process; often making your request 10x slower, that's just the cost of doing business with JWTs in this context because the JWT needs to be verified on each request, and that entails having the public key, thus fetching the JWKS from options.urlJWKS on every single request. Fortunately, a JWKS doesn't change particularly frequently, fastify-jwt-webapp can cache the JWKS for options.cacheJWKSAge milliseconds, even a value like 10000 (10 seconds) will, in the long-term, add up to much less time spent fetching the JWKS and significantly snappier requests (well, at least until options.cacheJWKSAge milliseconds after the caching request, at which point the cache will be refreshed for another options.cacheJWKSAge milliseconds).


Key Default Description
service required auth0 This plugin makes use of "templates" that control the parameters that are sent to the IdP. Can be auth0 or o365 right now.
client_id required Your client ID.
client_secret required You client secret.
urlAuthorize required The URL that your IdP uses for login,, for example.
urlToken required The URL that your IdP uses for exchanging an authorization_code for access token(s), in this case a JWT,, for example.
urlJWKS required The URL that serves your JWKS,, for example.
cookie.domain required os.hostname() fastify-jwt-webapp works by setting a cookie, so you need to specify the domain for which the cookie will be sent.
redirect_uri required This is the URL to which an IdP should redirect in order to process the successful authentication,, for example.
pathCallback /callback fastify-jwt-webapp creates several endpoints in your application, this is one of them, it processes the stuff that your IdP sends over after successful authentication, by default the endpoint is /callback, but you can change that with this parameter. This is very related to the redirect_uri option mentioned above.
pathLogin /login This is the second endpoint that fastify-jwt-webapp adds, it redirects to urlAuthorize (with some other stuff along the way), it's /login by default, but you can change it to anything, it's just aesthetic.
pathSuccessRedirect / Where do you get redirected after successful authentication? pathSuccessRedirect, that's where.
pathExempt ['/login', '/callback'] An array of endpoint paths to be excluded from the actions of the plugin (unauthenticated routes).
nameCredentialsDecorator credentials After successful authentication, the fastify request object will be decorated with the payload of the JWT, you can control that decorator here, req.theLoggedInUsersInfo for example.
authorizationCallback authorizationCallback is a totally optional function with signature async function(jwtResponse, request, reply) that is called after successful authentication, it has absolutely no effect on the plugin's actual functionality.
cacheJWKSAge (disabled) Will cache the JWKS for cacheJWKSAge milliseconds after the first request that needs it.
redirectOnFail false If set to true the plugin will redirect to pathLogin if a JWT is present, but not valid.


JWT authentication for fastify-based web apps








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