Laravel / PHP - Run 3 php functions in parallel

To me this looks more of like callback request for data, so to keep your app from not slowing down this should be a background job.

But before that I would implement an interface for those classes:

interface apiService{

   public function fetch();
}

Class api1 implements apiService {

  public function fetch()
  {
     //Do Something
  }

}

Class api2 implements apiService{

  public function fetch()
  {
    //Do Something
  }

}

Create a job class php artisan make:job dataFetcher

Jobs will be structured under App\Jobs\

The job class in Laravel its dead simple, consisting of a constructor to Inject dependencies and handle() to fire the job.

   protected $service;

   public function __construct(apiService $service)
   {
        $this->service = $service;
   }

   public function handle()
   {
       $this->apiService->fetch();
   }

Note that I am injecting the interface instead of concrete class, using a bit more high level code here. So now you can create a command to fire the calls with a cron job, or you can create a custom service provider to fire the commands as soon as app bootstraps.

I would go with a custom artisan command here:

So just create a custom artisan command on handle method

public function handle()
{
   Job::dispatch(new FirstApiClass);
   Job::dispatch(new SecondApiClass);
}

Handle method will execute first line and Job will be processed in background(doesnt matter if job failed or not), then next call will be fired and so on...

Note the use of the interface in this case, Job class doesnt really care which service you are calling as long as you provide an implmenetation of it.