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Handling requests with a JS Backend SDK

To handle authenticated requests, use one of the following JS Backend SDKs.

Clerk Express SDK

The clerkMiddleware() function checks the request's cookies and headers for a session JWT. If the user has a valid session, the clerkMiddleware() function attaches the properties of the authenticated user to the request object.

import { clerkMiddleware } from '@clerk/express'

const app = express()

// Pass no parameters
app.use(clerkMiddleware())

// Pass options
app.use(clerkMiddleware(options))

For more information on the Middleware functions and SDK features, see the Express SDK page.

Clerk Fastify SDK

The clerkPlugin checks the request's cookies and headers for a session JWT. If the user has a valid session, the clerkPlugin attaches the properties of the authenticated user to the request object.

import 'dotenv/config'
import Fastify from 'fastify'
import { clerkClient, clerkPlugin, getAuth } from '@clerk/fastify'

const fastify = Fastify({ logger: true })

fastify.register(clerkPlugin)

fastify.get('/', async (request, reply) => {
  const { userId } = getAuth(request)

  // Protect the route from unauthenticated users
  if (!userId) {
    return reply.code(403).send({ error: 'Unauthorized request.' })
  }

  const user = userId ? await clerkClient.users.getUser(userId) : null

  return reply.send({
    message: 'User retrieved successfully.',
    user,
  })
})

const start = async () => {
  try {
    await fastify.listen({ port: 8080 })
  } catch (error) {
    fastify.log.error(error)
    process.exit(1)
  }
}

start()

For more information on the Clerk plugin and SDK features, see the Fastify SDK page.

Clerk Backend SDK

If you're not using Express or Fastify, use the @clerk/backend package to access clerkClient.

import { createClerkClient } from '@clerk/backend'

const clerkClient = createClerkClient({
  secretKey: process.env.CLERK_SECRET_KEY,
  publishableKey: process.env.CLERK_PUBLISHABLE_KEY,
})

const { isSignedIn } = await clerkClient.authenticateRequest(req, {
  jwtKey: process.env.CLERK_JWT_KEY,
  authorizedParties: ['https://example.com'],
})

if (!isSignedIn) {
  return Response.json({ status: 401 })
}

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