The official currency of Vietnam is dong.
The exchange rate is about US$1 = 23,700 VND and €1 = 25,000 VND, as of September 2023), however it is quite variable.
The credit card is accepted in many places and you can withdraw money in the many ATMs of the country however remember to check with your bank what are the fees for this and VISA and MASTERCARD cards are accepted. However, the withdrawal limit is 5,000,000 VND, so for larger withdrawals, go to the bank desk with your passport between 8 a.m. and 11:30 a.m. or from 1 p.m. to 4:30 p.m. Monday to Friday.
Thus, we strongly recommend that you provide cash for your trip, for euros as well as for the dollars of banknotes of 50 or more in perfect condition, which you can easily change in jewelry stores where you can benefit from the best rate.
Finally, note that for dongs, there are banknotes of different denominations ranging from 1,000 to 500,000 VND, and pay attention to notes of 20,000 and 500,000 that are of similar color.