Yes it is. You need to pay accommodation and I’d suggest a 4 people couchette compartment.

Price depends on travel date (dynamic pricing), have a look at https://www.nightjet.com/en/#/home and book there (add Interrail/Eurail as a discount).

That’s great, thanks for the reply. 
 

Do you know when the tickets are released pleased? The train journey is showing but it’s not displaying any options to book any of the compartments. 
 

Thank you 

It probably depends on works on the French side. The train is sometimes diverted and doesn’t serve Strasbourg. Right now bookings seem to be open until mid-May.

Check regularly, it’s the only thing you can do honestly.

Btw if you wish to have a longer night you could board the night train in Salzburg 2 hours earlier. Only the departure day counts as a pass day so be aware of that.

That’s great, thanks for the advice.

Do you know at what point you add the Eurail tickets? I can only see the full price options for the dates until mid May, as if I was buying without Eurail. 
 

Thanks!

On the main search page under “Passengers...” you need to select discount and add in Interrail/Eurail for each passenger.

Thank you, I can see that now. 

It doesn’t look like handing a Eurail pass changes the price from the standard rate, or at least not very much. Unless I’m missing something!

sometimes the reservation for Eurail and the saver tickets (pre booking) have not much difference, depends from the algorythm.

Stadard full price tickets cost lot more.