How long is my Dutch NS train?

So you're in the Netherlands, waiting for your train. Wouldn't it be easy to know what length the incoming train will be? So you can wait apart from the crowd, board easily and have a comfy seat instead of having to stand the whole trip. Now you have the info, all you have to do is pick a spot on the platform! The Treinlengte-app shows the closest NS-stations near you.