Middleware

The ThunderID Next.js SDK provides Edge Runtime-compatible middleware for automatic token refresh and route protection.

thunderIDProxy()

Create a Next.js middleware that handles authentication concerns for every request.

middleware.ts

import {
  thunderIDProxy,
  createRouteMatcher,
} from '@thunderid/nextjs/server'

const isProtectedRoute = createRouteMatcher(['/dashboard(.*)'])

export default thunderIDProxy(async (thunderid, request) => {
  if (isProtectedRoute(request)) {
    await thunderid.protectRoute()
  }
})

export const config = {
  matcher: ['/((?!_next/static|_next/image|favicon.ico).*)'],
}

Parameters

Parameter	Type	Description
handler	(thunderid, request) => Promise<void>	Optional callback that receives the auth context and the request
options	ThunderIDProxyOptions	Optional configuration overrides

Proxy Context

The thunderid object passed to your handler provides:

Method	Return Type	Description
getSession()	Promise<SessionTokenPayload | undefined>	Retrieve the current session payload
getSessionId()	string | undefined	Retrieve the current session ID
isSignedIn()	boolean	Check whether the user is authenticated
protectRoute(options?)	Promise<NextResponse | void>	Redirect unauthenticated users to the sign-in page

protectRoute() Options

Option	Type	Description
redirect	string	Custom URL to redirect unauthenticated users to. Defaults to the configured signInUrl

createRouteMatcher()

Create a function that matches requests against a list of route patterns.

import { createRouteMatcher } from '@thunderid/nextjs/server'

const isProtectedRoute = createRouteMatcher([
  '/dashboard(.*)',
  '/admin(.*)',
  '/settings(.*)',
])

Parameters

Parameter	Type	Description
patterns	string[]	Array of glob-like route patterns

Returns: (req: NextRequest) => boolean

Automatic Token Refresh

The middleware automatically refreshes access tokens that are about to expire (within 25 seconds of their expiry). This happens transparently:

1. The middleware reads the session cookie from the request
2. If the token expires soon, the middleware calls the refresh endpoint
3. The updated session cookie is set on both the response and the forwarded request headers
4. Your page components and server actions always receive a valid token

Examples

Protect Multiple Route Groups

middleware.ts

import {
  thunderIDProxy,
  createRouteMatcher,
} from '@thunderid/nextjs/server'

const isProtectedRoute = createRouteMatcher([
  '/dashboard(.*)',
  '/settings(.*)',
  '/api/private(.*)',
])

const isAdminRoute = createRouteMatcher(['/admin(.*)'])

export default thunderIDProxy(async (thunderid, request) => {
  if (isAdminRoute(request)) {
    await thunderid.protectRoute({ redirect: '/unauthorized' })
    return
  }

  if (isProtectedRoute(request)) {
    await thunderid.protectRoute()
  }
})

export const config = {
  matcher: ['/((?!_next/static|_next/image|favicon.ico).*)'],
}

Access Session Data in Middleware

middleware.ts

import { thunderIDProxy } from '@thunderid/nextjs/server'

export default thunderIDProxy(async (thunderid, request) => {
  const session = await thunderid.getSession()

  if (session) {
    console.log('Authenticated user:', session.sub)
  }
})

export const config = {
  matcher: ['/((?!_next/static|_next/image|favicon.ico).*)'],
}