Is there any app that let's you call for free worldwide?

Yes, You can make free international video calls are possible. Simply open your browser, enter the phone number and enjoy free phone calls around the world. 100% free. No need to sign up.

And I have also used free video calling app. And this app best video call feature's are available below it is:-

Unlimited 100% free video call chat

Excellent quality of video

Sort by gender

No need to log in.

You can create live video chat rooms

Make fake celebrity's video call

You can just try it.

MeetMatch: Stranger Video Chat