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CI npm version js-standard-style

@fastify/bearer-auth provides a simple request hook for the Fastify web framework.


'use strict'

const fastify = require('fastify')()
const bearerAuthPlugin = require('@fastify/bearer-auth')
const keys = new Set(['a-super-secret-key', 'another-super-secret-key'])

fastify.register(bearerAuthPlugin, {keys})
fastify.get('/foo', (req, reply) => {
  reply.send({authenticated: true})

fastify.listen({port: 8000}, (err) => {
  if (err) {


@fastify/bearer-auth exports a standard Fastify plugin. This allows you to register the plugin within scoped paths. Therefore, you could have some paths that are not protected by the plugin and others that are. See the Fastify documentation and examples for more details.

When registering the plugin you must specify a configuration object:

  • keys: A Set or array with valid keys of type string (required)
  • function errorResponse (err) {}: method must synchronously return the content body to be sent to the client (optional)
  • contentType: If the content to be sent is anything other than application/json, then the contentType property must be set (optional)
  • bearerType: string specifying the Bearer string (optional)
  • function auth (key, req) {} : this function will test if key is a valid token. The function must return a literal true if the key is accepted or a literal false if rejected. The function may also return a promise that resolves to one of these values. If the function returns or resolves to any other value, rejects, or throws, a HTTP status of 500 will be sent. req is the Fastify request object. If auth is a function, keys will be ignored. If auth is not a function, or undefined, keys will be used.
  • addHook: If false, this plugin will not register onRequest hook automatically, instead it provide two decorations fastify.verifyBearerAuth and fastify.verifyBearerAuthFactory for you.
  • verifyErrorLogLevel: An optional string specifying the log level when there is a verification error. It must be a valid log level supported by fastify, otherwise an exception will be thrown when registering the plugin. By default, this option is set to error.

The default configuration object is:

  keys: new Set(),
  contentType: undefined,
  bearerType: 'Bearer',
  errorResponse: (err) => {
    return {error: err.message}
  auth: undefined,
  addHook: true

Internally, the plugin registers a standard Fastify preHandler hook, which will inspect the request's headers for an authorization header with the format bearer key. The key will be matched against the configured keys object via a constant time algorithm to prevent against timing-attacks. If the authorization header is missing, malformed, or the key does not validate then a 401 response will be sent with a {error: message} body; no further request processing will be performed.

Integration with @fastify/auth

This plugin can integrate with @fastify/auth by following this example:

const fastify = require('fastify')()
const auth = require('@fastify/auth')
const bearerAuthPlugin = require('@fastify/bearer-auth')
const keys = new Set(['a-super-secret-key', 'another-super-secret-key'])

async function server() {

  await fastify
    .register(bearerAuthPlugin, { addHook: false, keys, verifyErrorLogLevel: 'debug' })
    .decorate('allowAnonymous', function (req, reply, done) {
      if (req.headers.authorization) {
        return done(Error('not anonymous'))
      return done()

    method: 'GET',
    url: '/multiauth',
    preHandler: fastify.auth([
    handler: function (_, reply) {
      reply.send({ hello: 'world' })

  await fastify.listen({port: 8000})


By passing { addHook: false } in the options, the verifyBearerAuth hook, instead of immediately replying on error (reply.send(someError)), invokes done(someError). This will allow fastify.auth to continue with the next authentication scheme in the hook list. Note that by setting { verifyErrorLogLevel: 'debug' } in the options, @fastify/bearer-auth will emit all verification error logs at the debug level. Since it is not the only authentication method here, emitting verification error logs at the error level may be not appropriate here. If verifyBearerAuth is the last hook in the list, fastify.auth will reply with Unauthorized.


MIT License