Hey,

AFAIK there is no reservation needed from Zagreb to Budapest and usually this trains are not very crowded. 

Did you make this trip? I just asked at the station and as far as I understood the ticket agent was saying there was no need for reservations

I did it many years ago and there was no reservation needed. Still should be the same. Just hop on the train.

There is a direct train from Zagreb Glavni Kol. to Budapest-Kelenfoeld (IC 205) which does not require a reservation. You can find the train in our planning tools. If this trip is not available yet, it might be too far in the future or our app hasn't synced up with the latest timetable changes yet. If the latter applies, then you can always add this journey manually. 

Hi, we are in June 2024, and now for the IC201 the app show a 6€ fees reservation needed but not possible to buy. Can interrail team look at it please ? Thank you

Don't book via Interrail if you can avoid it.

You can book for €3 at either tickets.oebb.at or cd.cz. If it doesn't work for you, please mention your travel date.