Add Custom Header to Every Response in Laravel 9

For some applications, there might be a requirement to add a custom HTTP header to all the responses. It can be done by adding header on each controller method. However, a better solution is to add header globally to all the responses.

This tutorial provides example how to add custom header to every response in Laravel 9 application.

Create a new middleware and add a custom HTTP header to response.

app/Http/Middleware/AddHeadersToResponse.php

<?php

namespace App\Http\Middleware;

use Closure;
use Illuminate\Http\Request;

class AddHeadersToResponse
{
    public function handle(Request $request, Closure $next): mixed
    {
        $response = $next($request);
        $response->header('X-App-Message', 'Hello world');

        return $response;
    }
}

Define the middleware in the middleware array which can be found in the Kernel.php file.

app/Http/Kernel.php

<?php

namespace App\Http;

use App\Http\Middleware\AddHeadersToResponse;
use Illuminate\Foundation\Http\Kernel as HttpKernel;

class Kernel extends HttpKernel
{
    protected $middleware = [
        // ...
        AddHeadersToResponse::class,
    ];

    // ...
}

Response headers can be verified using web browser: